rexresearch.com
rexresearch.com
Roger & Derek HINE
Wave-Power Boat
http://www.forbes.com/sites/toddwoody/2012/12/05/ocean-robot-completes-record-setting-10000-mile-journey/
Ocean Robot Completes Record-Setting 10,000 Mile Journey
The Mars rover Curiosity may be the most famous robot on – or off – the planet but an ocean-going bot named Papa Mau just set a world’s record for robot-kind by traveling more than 10,000 miles from San Francisco to Australia powered only by waves and sunlight.
Liquid Robotics, the Silicon Valley startup that makes the surfboard-sized robot called a Wave Glider, announced Wednesday that Papa Mau arrived off the coast of Queensland, Australia, on Nov. 20 after surviving storms, sharks and 25-foot surf while its solar-powered sensor arrays collected terabytes of data on ocean and atmospheric conditions during the year-long journey.
“The vehicle actually surprised me by the condition it was in when we pulled it out,” Graham Hine, Liquid Robotics’ senior vice president of product management, told me Wednesday. “The paint was scuffed and there was some wear on the bushings but other than that and a few critters attached here and there it could have kept going.”
“We haven’t pushed the absolute endurance of these vehicles even with this ocean crossing,” he added, noting that barnacles, a crab and a spiny worm had hitched a ride on Papa Mau. “We would like to go further.”
As I wrote last year in a feature story on Liquid Robotics, the company has deployed Wave Gliders around the world where they are undertaking missions for climate scientists, oil companies and the U.S. military:
Packed in their 7-by-2-foot titanium-framed fiberglass bodies are terabytes of cellphone flash storage, a dual-core ARM processor running open Linux software, a battery pack, sensor arrays, a GPS unit, and wireless and satellite communications systems. It’s all powered by two off-the-shelf solar panels that cover the top of the Glider.
But it is what’s unseen 23 feet below the ocean’s surface that makes the Wave Glider a perpetual motion green machine and that its investors are gambling will mint money from oil companies, scientists and the military. Tethered to the floating vehicle are six three and-a-half-foot “fins” attached to a rudder. As the fins tap the energy generated by the up-and-down motion of ocean waves, they move to propel the robot at speeds of up to 2 knots. No fuel—fossil or otherwise—required.
The Wave Glider’s capacity to operate autonomously at sea for months on end gathering data from uncharted reaches of the ocean has attracted $40 million in funding, including $22 million from VantagePoint Capital Partners, a leading Silicon Valley green tech investor, and oil industry services behemoth Schlumberger.
PacX, as Liquid Robotics calls the Pacific Ocean crossing, was conceived to demonstrate the Wave Gliders’ endurance while collecting data for scientists.
Four Wave Gliders departed San Francisco on Nov. 17, 2011, for Hawaii where Papa Mau and a companion robot, Benjamin, headed to Australia while two others, Piccard Maru and Fontaine Maru, set off for Japan.
Benjamin currently is passing the island nation of New Caledonia about 750 miles east of Australia and is expected to complete its journey early next year.
The Japan-bound robots weren’t so lucky. Both experienced rudder problems that left them adrift. Hine says a ship has picked up Fontaine Maru and is bringing it back to the Liquid Robotics R&D facility in Hawaii.
“We want to see if we can modify it and restart its voyage to Japan,” he says. “We don’t know if there was something about the Japan crossing that caused the failure of if it was something with the units themselves.
Papa Mau faced its own challenges, including long stretches of cloudy days that made it difficult for its two solar panels to collect enough energy to power its sensor arrays. But the robot sailed through equatorial waters without a hitch despite fears that strong currents and a lack of waves would take Papa Mau off course.
Liquid Robotics customers can either buy the $100,000 robots or just the data they collect for an annual subscription that’s a fraction of the cost of dispatching a deep ocean ship and crew to do the same job.
Hine says he hopes Papa Mau’s record-setting journey for an autonomous vehicle will be a persuasive sales pitch to potential clients.
“This has been a technology where people haven’t believed it could do what we say it could,” says Hine. “So for this little robot to survive for thousands of miles for a year is a tremendous credibility jump for us.”
As part of the mission supported by Richard Branson’s Virgin Oceanic and Google Earth, Liquid Robotics sponsored the PacX Challenge, which will award $50,000 grant from BP – one of the company’s clients – and six months of Wave Glider services to the scientist that comes up with the best research proposal based on the data collected during the Pacific crossing.
On Wednesday, Liquid Robotics said that it had selected five finalists for the grand prize: J. Michael Beman of the University of California Merced, Nicole Goebel of University of California Santa Cruz, Andrew Lucas, of the Scripps Institution of Oceanography, Tracy Villareal of the University of Texas and oceanographer Elise Ralph of the Boston software company Wise Eddy.
So what’s next for Papa Mau?
Hine says his colleagues are considering an even bigger challenge for the robot. “We may end up putting it in a museum but I would like to see it retasked and sent off for another journey, such as circumnavigating Antarctica or heading from the South Poll to the North Poll and making it through Northwest Passage.”
WO2012126009
WAVE-POWERED DEVICES CONFIGURED FOR NESTING
Inventor:
HINE ROGER G ; HINE DEREK
Applicant: LIQUID ROBOTICS INC
CPC: F03B13/1885 // F03B13/20
IPC: B63H1/36 // B63H19/02
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from and the benefit of the following provisional patent applications:
- U.S. Application No. 61/453,871, filed March 17, 2011, for "Wave-Powered Vehicles (JUP 012)" (Roger G. Hine);
- U.S. Application No. 61/502,279, filed June 28, 2011 , for "Energy-Harvesting Water Vehicle" (Roger G. Hine);
- U.S. Application No. 61/535,116, filed September 15, 2011, for "Wave-Powered Vehicles (JUP 012-1)" (Roger G. Hine); and
- U.S. Application No. 61/585,229, filed January 10, 2012, for "Retractable Nesting Wing Racks for Wave Powered Vehicle" (Roger G. Hine and Derek L. Hine).
[0002] The following three applications (including this one) are being filed
contemporaneously :
- U.S. Application No. , filed , for "Wave-Powered Device with One or
More Tethers Having One or More Rigid Sections" (Roger G. Hine);
- U.S. Application No. , filed , for "Wave-Powered Devices Configured for Nesting" (Roger G. Hine and Derek L. Hine); and
- U.S. Application No. , filed , for "Autonomous Wave Powered
Substance Distribution Vessels for Fertilizing Plankton, Feeding Fish, and
Sequestering Carbon From The Atmosphere" (Roger G. Hine).
[0003] This application is also related to the following U.S. and International patent applications:
- U.S. Application No. 1 1/436,447, filed May 18, 2006, now U.S. Patent 7,371,136;
- U.S. Application No. 12/082,513, filed April 1 1, 2008, now U.S. Patent 7,641,524;
- U.S. Application No. 12/087,961, based on PCT/US 2007/001 139, filed January 18, 2007, now U.S. Patent 8,043,133;
- International Patent Application No. PCT/US 2007/01 139, filed January 18, 2007, published August 2, 2007, as WO 2007/087197; - International Patent Application no. PCT US 2008/002743, filed February 29, 2008, published September 12, 2008, as WO 2008/109002;
- U.S. Application No. 61/453,862, filed March 17, 2011, for "Distribution of
Substances and/or Articles into Wave-Bearing Water (JUP 013)" (Roger G. Hine); and
- The U.S. and PCT applications filed on or about the same day as this application and claiming priority from U.S. Provisional Application Nos. 61/453,862 and 61/535,116.
[0004] The entire disclosure of each of the above-referenced patents, applications, and publications is incorporated herein by reference for all purposes.
BACKGROUND OF THE INVENTION
[0005] This invention relates to devices that are subject to waves in the water, and that in some cases utilize the power of waves in water.
[0006] As a wave travels along the surface of water, it produces vertical motion, but no net horizontal motion, of water. The amplitude of the vertical motion decreases with depth; at a depth of about half the wavelength, there is little vertical motion. The speed of currents induced by wind also decreases sharply with depth. A number of proposals have been made to utilize wave power to do useful work. Reference may be made, for example, to U.S. Patent Nos. 986,627, 1,315,267, 2,520,804, 3,312,186, 3,453,981, 3,508,516, 3,845,733, 3,872,819, 3,928,967, 4,332,571, 4,371,347, 4,389,843, 4,598,547, 4,684,350, 4,842,560, 4,968,273, 5,084,630, 5,577,942, 6,099,368 and 6,561,856, U.S. Publication Nos. 2003/0220027 and 2004/0102107, and International Publication Nos. WO 1987/04401 and WO 1994/10029. The entire disclosure of each of those patents and publications is incorporated herein by reference for all purposes.
[0007] Many of the known wave-powered devices ("WPDs") comprise (1) a float, (2) a swimmer, and (3) a tether connecting the float and the swimmer; the float, swimmer, and tether being such that when the vehicle is in still water, (i) the float is on or near the surface of the water, (ii) the swimmer is submerged below the float, and (iii) the tether is under tension, the swimmer comprising a fin or other wave-actuated component which, when the device is in wave-bearing water, interacts with the water to generate forces that can be used for a useful purpose, for example to move the swimmer in a direction having a horizontal component (hereinafter referred to simply as "horizontally" or "in a horizontal direction"). The terms "wing" and "fin" are used interchangeably in the art and in this application. [0008] It is desirable to position sensors and equipment in the ocean or lakes for long periods of time without using fuel or relying on anchor lines which can be very large and difficult to maintain. In recent years, the WPDs developed by Liquid Robotics, Inc. and marketed under the registered trademark Wave Glider<(R)>, have demonstrated outstanding value, particularly because of their ability to operate autonomously. It is noted that Wave Glider<(R)> WPDs are often referred to as Wave Gliders as a shorthand terminology. It is also noted that WPDs are often referred to as wave-powered vehicles ("WPVs").
SUMMARY OF THE INVENTION
[0009] A problem that arises with the known wave-powered devices is that they are difficult to transport, store, launch, and recover. Embodiments of the present invention provide a solution this problem by providing an assembly in which the tether and the wave- actuated component are nested closely to, and/or secured to, the float, thus making relatively compact assembly that can be maintained as a single unit until the time comes to launch the device on the water. A related solution, which is applicable when the tether, in use, is rigid, is described and claimed in detail in an application filed contemporaneously with this application and also claiming priority from U.S. Provisional Application Nos. 61/453,871 and 61/535,116. That related solution, which can be used in conjunction with the solution of this invention, it is to make use of a tether which, before the device is placed on water, can be maintained in a position adjacent to the float and which, before or after the device is placed on water, can be moved from the adjacent position to an extended position in which the tether is at least in part rigid.
[0010] The Summary of the Invention and the Detailed Description below, and the accompanying drawings, disclose many novel features, each of which is inventive in its own right, and any one or more of which can be used in combination where this is physically possible. The different aspects of the invention identified below are no more examples of the broad range of inventions disclosed herein.
[0011] In a first aspect of this invention, an assembly comprises: (1) a float; (2) a wave- actuated component; and (3) a closure component having a first state in which it secures the float and the wave-actuated component together as an assembly that can be moved as a unit and a second state that permits the wave-actuated component to move away from the float. The assembly is configured to accept a tether having a first end connected to the float and a second end connected to the wave-actuated component, such that when the closure component is in the second state and the assembly includes such a tether, the float, the tether, and the wave-actuated component form a wave-powered device (WPD). [0012] When the float is placed on or near the surface of still water, the WPD has (a) the float floating on or near the surface of the still water, (b) the tether extending downwards from the float and under tension, and (c) the wave-actuated component being submerged below the float. When the float is placed on or near the surface of wave-bearing water, the WPD has (a) the float floating on or near the surface of the wave-bearing water, (b) the tether extending downwards from the float, and (c) the wave-actuated component being submerged below the float, and interacting with the water to generate forces that are transmitted to the tether.
[0013] The wave-actuated component is sometimes referred to herein as a "swimmer" or a "wing rack" (for those embodiments having multiple fins. It can comprise a fin system as disclosed in any of the documents incorporated herein by reference or any other mechanism that will interact with the water to generate forces that are transmitted to the tether.
[0014] In a second aspect of the invention, a float having top, bottom, and side surfaces comprises float side components that extend downwards from the side surfaces to create a space defined by the bottom surface and the float side components. Such a float is, for example, useful in the first aspect of the invention because the defined space can enclose the wave-actuated component.
[0015] In a third aspect of the invention, a wave-actuated component comprises components that extend upwards from the wave-actuated component and that will interact with a float to register the wave-actuated component in relation to the float.
[0016] In a fourth aspect of the invention, a wave-actuated component comprises components that extend downwards from the wave-actuated component, and when the wave- actuated component is placed upon a horizontal surface, the components that extend downwards separate the surface from any part of the wave-actuated component that might otherwise be damaged by contact with the surface.
[0017] In a fifth aspect of the invention, a wave-powered device comprises: (1) a float, (2) a flexible tether, and (3) a wave-actuated component, the tether connecting the float and the wave-actuated component. The float, the tether, and the wave-actuated component are such that, when (A) the device is in still water, (i) the float is on or near the surface of the water, (ii) the wave-actuated component is submerged below the float, and (iii) the tether is under tension, and (B) when the device is in wave-bearing water, the wave-actuated component interacts with the water to generate forces that are transmitted to the tether. In this aspect, the float comprises a winch that can be operated to change the length of the tether. [0018] In a sixth aspect of the invention, a wave-powered device comprises: (1) a float, (2) a flexible tether, and (3) a wave-actuated component, the tether connecting the float and the wave-actuated component. The float, the tether, and the wave-actuated component are such that (A) when the device is in still water, (i) the float is on or near the surface of the water, (ii) the wave-actuated component is submerged below the float, and (iii) the tether is under tension, and (B) when the device is in wave-bearing water, the wave-actuated component interacts with the water to generate forces that are transmitted to the tether, wherein the tether has at least one of the following characteristics:
(1) the tether has a substantially flat configuration, for example with an average
thickness of 1-3 mm;
(2) the tether is free from components that carry electrical currents and/or is free from components that carry signals of any kind;
(3) the tether comprises a plurality of round tensile members;
(4) the tether is a flat webbing constructed of a synthetic polymer, e.g., a polyamide,.
Spectran, Vectran, or Kevlar;
(5) the tether is a flat webbing that is tensioned only along the leading edge thereof, thus reducing fluttering and bowing;
(6) the tether is attached to the float at a hinge point that comprises a shaft and bushing arrangement such that the tether is not required to flex against its wide axis (pitch);
(7) at the float, the tether is guided through a 90[deg.] twist, and then flexes in the pitch axis over a pulley with its axis level and perpendicular to the longitudinal axis of the float;
(8) at the float, the tether is guided through a 90[deg.] twist, and then flexes in the pitch axis over a pulley with its axis level and perpendicular to the longitudinal axis of the float, wherein the pulley is crowned to increase the tension on the center of the tether to lessen the effect of the the 90[deg.] twist increasing the tension of the outer parts of the tether, relative to the center of the tether.
[0019] In an seventh aspect of the invention, a fin system for use in a wave-powered device of any kind, including the wave-powered devices disclosed in the documents incorporated by reference herein, has at at least one fm that rotates about an axis and that has a neutral position, and a control system for controlling the rotation of the fin, and the control system comprises: a first means that controls the rotation of the fin within a first range about a neutral position; and a second means that controls the rotation of the fm when the movement of the fins is outside the first range. In embodiments, the angular movement of at least one fin is primarily controlled by a first spring or other means when the movement of the fins is within a first range about a neutral position and is primarily controlled by a second spring or other means when the movement of the fins is within a second range that is outside the first range, wherein the second spring is stiffer than the first spring, thus making it more difficult for the fins to move within the first range. The movement can be controlled solely by the first spring or by a combination of first spring and a second spring.
[0020] Within the second range, the movement can be controlled solely by the second spring or by a combination of the first spring and a second spring. The system can include a stop that prevents the first spring from moving beyond a first limit. The system can include a stop that prevents the second spring from moving beyond a second limit, and thus prevents the fin from moving outside a second range. Either or both of the springs can be replaced by an equivalent means that may be mechanical or electromechanical. When using such a system, when the waves in the wave bearing water are small, the rotation of the fins is controlled by the first spring and only a little fluid force is needed to rotate the fins to an angle within an effective range. As the waves become larger, the second spring comes into play and, by preventing the fins from "overrotating" maintains the fins at an angle within an effective range. Excessive water forces can rotate the wing so that it dumps the load, thus protecting the system from overload.
[0021] In an eighth aspect of the invention, a method of obtaining information comprises receiving signals from, or recorded by, a WPD according to the first, fifth, or sixth aspect of the invention, or a WPD that comprises a float according to the second aspect of the invention, or a wave-actuated component according to the third or fourth aspect of the invention, or a WPD that comprises a fin system according to the seventh aspect of the invention. [0022] In a ninth aspect of the invention, a method for controlling a function of a WPD comprising sending signals to a WPD according to the first, fifth, sixth, or seventh aspect of the invention, or a WPD that comprises a float according to the second aspect of the invention, or a wave-actuated component according to the third or fourth aspect of the invention, or a WPD that comprises a fin system according to the seventh aspect of the invention.
Nesting
[0023] The assembly of the first aspect of the invention makes use of a float and a wave- actuated component that are designed to fit closely to each other, e.g., in a nested or bundled configuration. For example, the float can comprise components that extend downwards and fit around the swimmer, and/or the swimmer can comprise components that extend upwards and fit around the float. One or both of the float and the wave-actuated component can include clips that help to secure the float and the swimmer together. Alternatively or additionally, one or more separate components, e.g., straps, can secure the float and the wave- actuated component together. [0024] Fins forming part of the wave-actuated component can remain within, or extend beyond, the periphery of the float. This makes it easier for the float and the wave-actuated component to be handled as a single unit for storage and/or transport, before being launched as a WPD and can also facilitate recovery of the WPD. In some cases, the float and the swimmer can together form a package that can be handled as a single unit for shipping within recognized national and/or international weight and dimension restrictions. The combination of the float and the wave-actuated component can include the tether, so that, when the components are separated, there is a WPD ready for use. Alternatively, the tether can be absent from the package and be added to the assembly when the WPD is ready to be launched. The tether can comprise one or more rigid sections that can be folded, telescoped or otherwise collapsed, or a tether that can be wound up on a winch on the float.
[0025] In another aspect of the invention, a method of launching a WPD comprises (1 ) providing a WPD precursor that comprises a float and a wave-actuated component that are nested together, and a tether that is coiled and/or folded within the float and/or the wave- actuated component, and/or between the float and the wave-actuated component; (2) placing the WPD precursor on water; and (3) releasing the wave-actuated component from the float so that the wave-actuated component is submerged below the float and the tether is under tension between the float and the wave-actuated component.
[0026] In another aspect of the invention, a method of recovering a WPD that comprises a float, a wave-actuated component, and at least two tethers, that link the float and the wave- actuated component, the method comprising pulling one of the tethers upwards so that fins on the wave-actuated component have reduced resistance to upward motion.
[0027] In another aspect of the invention, a method of recovering a WPD that comprises a float, a wave-actuated component, and a tether that comprises at least one rigid section, the method comprising folding the tether upwards so that fins on the swimmer have reduced resistance to upward motion.
[0028] In another aspect of the invention, a WPD in which the tether is free from components that carry electrical currents and/or is free from components that carry signals of any kind. In this case, the wave-actuated component will generally also be free from electrical and electronic components. This reduces the danger that the performance of the WPD will be compromised by damage to the tether, particularly when making use of a tether that is flexible, since it is difficult to prevent failure of electrical wires in the tether, since the tether can be subject to large snap loads, and bending loads, resulting in damage to insulation surrounding electrical/electronic components, which in turn results in failure due to salt water incursion. Tethers without electrical wires can be thinner, and stiffer, and can have cross sections that make it easier to store the tether before the WPD is launched and/or to gather up the tether when the WPD is to be removed from the water.
[0029] A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings, which are intended to be exemplary and not limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a pictorial view showing the operation of a wave-powered device ("WPD") in still water (fins/wings in neutral position), when a wave lifts the float (up- stroke), and when the WPD sinks into the wave trough (down-stroke);
[0031] FIG. 2A is a perspective view taken from above of a WPD having two rigid tethers and a wave-actuated component having two horizontal rigid spines (side beams) and a fin system between the rigid spines, with the tethers in their extended positions;
[0032] FIG. 2B is a perspective view taken from above of the WPD of FIG. 2A with the rigid tethers in their retracted positions so that the WPD is in a bundle cofiguration with the float sitting atop the wave-actuated component;
[0033] FIGS. 3A and 3B are perspective views taken from the bottom of the WPD of FIGS. 2A and 2B;
[0034] FIG. 4 is a perspective end view of a WPD showing three wing racks;
[0035] FIG. 5 A is an end view of the WPD of FIG. 4 with the wing racks having been retracted and nested;
[0036] FIG. 5B is an enlarged view showing addition details of the nested wing racks shown in FIG. 5 A;
[0037] FIG. 6 is an end view showing two WPDs of the type shown in FIG. 5 A, both in their retracted configurations stowed in a container;
[0038] FIG. 7A is a perspective view from the bottom showing a WPD of the type shown in FIG. 5A with the wing racks retracted and a sensor payload array lowered through a central opening in the wing racks;
[0039] FIG. 7B is a perspective view from the top showing the wing racks lowered and the sensor payload array deployed below them;
[0040] FIGS. 8A, 8B, 8C, and 8D are end, top, side, and bottom views of a configuration suitable for compact stowing and transport where the wing rack or racks can nest in a recess in the bottom of the float;
[0041] FIG. 9 shows four such nested WPDs being transported on a flatbed trailer;
[0042] FIG. 1OA is a perspective view showing a two-spring arrangement for controlling the movement of a fin (not shown), which is part of a wave-actuated component such as any of the WPDs described herein, viewed looking from between the spines (side beams);
[0043] FIG. 10B is a partially cutaway perspective view showing the two-spring arrangement with one end of each spring embedded in the fin, viewed looking from outside the spines (side beams);
[0044] FIG. 11 is a graph of spring torque as a function of fin (wing) angle;
[0045] FIGS. 12A and 12B are external and cutaway perspective views of a winch that can be used with embodiments of the present invention;
[0046] FIG. 13 is a is a block diagram of a control system of the type that might be used in any of the WPDs discussed herein for directing the WPD along a desired path; and
[0047] FIG. 14 is a block diagram schematically showing some of the ways that a representative WPD communicates with outside entities.
DESCRIPTION OF SPECIFIC EMBODIMENTS
Overview
[0048] FIG. 1 is a side view showing three images of a wave-powered water vehicle. The vehicle comprises a "float" 10 resting on the water surface, and a "swimmer" or "glider" 20 hanging below, suspended by a tether 30. The float 10 comprises a displacement hull 11 and a fixed keel fin 12. The swimmer comprises a rudder 21 for steering and "wings" or "fins" 22 connected to a central beam of the rack 23 so as to permit rotation of the wings around a transverse axis within a constrained range, and provide propulsion.
[0049] In still water (shown in the leftmost panel), the submerged swimmer 20 hangs level by way of the tether 30 directly below the float 10. As a wave lifts the float 10 (middle panel), an upwards force is generated on the tether 30, pulling swimmer 20 upwards through the water. This causers the wings 22 of the swimmer to rotate about a transverse axis were the wings are connected to the rack 23, and assume a downwards sloping position. As the water is forced downward through the swimmer, the downwards sloping wings generate forward thrust, and the swimmer pulls the float forward. After the wave crests (rightmost panel), the float descends into a trough. The swimmer also sinks, since it is heavier than water, keeping tension on the tether. The wings rotate about the transverse axis the other way, assuming an upwards sloping position. As the water is forced upwards through the swimmer, the upwards sloping wings generate forward thrust, and the swimmer again pulls the float forwards.
[0050] Thus, the swimmer generates forward thrust when either ascending or descending, resulting in forward motion of the entire craft.
Engaging and Securing Components of the Vehicle for Storage and Transport
[0051] Embodiments of the invention provide a technology for combining components of a multi-component wave-powered water vessel in a way that they can be stored or transported on land with minimal difficulty or damage.
[0052] One of the elements of this technology is an engagement means, wherein the components are configured to fit together in a manner that provides lateral support one component to another, and thereby minimizes lateral movement of one against the other when fitted together. In a two-way engagement means, the components are also configured to provide support one component to another in the longitudinal dimension, and thereby minimize longitudinal movement of one against the other when fitted together.
[0053] Lateral engagement means and optionally two-way engagement means between a float (the vessel body traveling on or near the surface of the water) and a swimmer (the rack of wings or fins that travels under water and provides locomotive force) may be provided by configuring the float and swimmer so that they fit together one inside the other, or are configured so that projections from one component, the other component, or both receive and engage the other component.
[0054] In one such configuration, the swimmer has a smaller width and optionally a smaller length compared with the outermost edges of the float. The float is provided with a compartment or is hollowed out at the bottom to a depth whereby when the swimmer is secured to or contained within the hollow, the hollow conforms closely to the shape of the swimmer, thus providing lateral and potentially longitudinal stability. The roles of the components may be reversed, so that the float fits into a hollow in the swimmer. In another configuration, the swimmer has lateral beams or brackets on both sides that extend upwards to brace inwards against the sides of the float. The roles of the components may be reversed, so that the float has a lateral bracket on both sides that extends downwards to brace inwards against the sides of the swimmer. More complex configurations can also be designed where the float and swimmer are both provided with brackets, and the brackets interdigitate to provide lateral support and thereby minimize lateral movement of one against the other.
[0055] Another element of the technology is an integral securing means, whereby one component is secured against and either above or below another component in a manner that the components may be moved together on land without one component sliding against another. The securing means is integral in the sense that it is built into one component, the other component, or both, so that it is always present and not removed after deployment of the vessel into the water. In this way, it is made available to resecure the vehicle back on land after a course of duty on the water.
[0056] One such integral securing means is a connection between the components that may connect the components at a distance, but can be reduced in the length of the connection until the components are urged against one another. For example, when a float suspends a swimmer by way of a tether, the float may be provided with a locking or ratcheting winch to draw the swimmer upwards against the bottom of the float. Alternatively or in addition, components of the vessel may be equipped with integral securing means such as a clasp, clamp, or bolt that mates with and may be secured against a complementary element of another component after the components are brought together.
[0057] FIGS. 2 A and 2 A are perspective views from the upper left side of another wave- powered water vehicle having a different configuration. FIG. 2A shows the vehicle as it is deployed in the water. In this example, the float 10 is connected to the swimmer 20 by two tethers 30. The float 10 comprises a displacement hull 11 with a side panel 13 on each side. The rudder 14 is now placed on the float. Upward facing solar panels 15 generate electrical power to supply the electronics (not shown) that are contained in one or more sealed compartments 16. The electronics control navigation, and have an antenna 17 to transmit data and receive instructions wirelessly to other vessels and/or a control unit on shore. The swimmer 20 comprises a rack 23 now positioned to support the wings 22 on either side. The rack 23 comprises a side beam 24 on each side that is configured to engage the hull 11 of the float. The rack 23 also comprises downward facing support legs 25 to support the entire vehicle from below when on land. [0058] FIG. 2B shows the vehicle when the swimmer 20 has been secured underneath the float 10 for transport or storage of the vehicle out of the water.
[0059] FIGS. 3A and 3B are perspective views from the lower left side of the same two- tether wave-powered vehicle. FIG. 3 A shows the vehicle as it is deployed in the water. Each tether 30 is secured to the swimmer at a midpoint 31 on a transverse beam 27 between the two side beams 24 of the rack 23. Each tether passes through an opening 18 in the hull 11 of the float so that they may be winched up together to lift the swimmer 20. The hull 11 also has four couplers 19 to secure the swimmer 20 to the float for transport.
[0060] FIG. 3B shows the vehicle as it is secured for transportation or storage. The swimmer 20 is secured to the hull 11 of the float by retraction of the tethers that are joined at a midpoint 31 of two transverse beams 27, and closing the couplers 19 against transverse beams in the swimmer.. The rudder 14 mounted on the float fits into a corresponding notch 26 on the rack 23 of the swimmer. The side beams 24 of the rack extend upwards to engage the sides 13 of the float.
[0061] In these figures, the side beams of the swimmer 20 constitute an engagement means by extending upwards so that they may engage opposite side panels of the float. There are also two types of securing means. One type is the two winches for bringing the two tethers up and into the float. When they are drawn in so that the swimmer is in the upmost position, the swimmer is secured against the bottom of the float. The other integral securing means is the four couplers 19 on the bottom of the float, which lock onto transverse beams of the swimmer.
Wave-Powered Vehicle Having Multiple Tiers of Fins that Nest Together
[0062] FIG. 4 shows a model of a wave-powered water vehicle that has multiple tiers of fins. Each of the three tiers (20a, 20b, and 20c) comprises a rack with a side beam on each side (24a, 24b, and 24c), and transverse beams (27a, 27b, and 27c) between the to sides. The upper tier 20a, the middle tier 20b, and the lower tier 20c are each secured to the tethers 30 at the midpoint 31 of the transverse beams 27. Each tether is mounted to a winch 32 in the float 10 to retract the three tiers against the float for storage or transport.
[0063] FIG. 5 A shows a cut-away view of the three tiers 20 secured to the float 10. The winch 32 has been used to pull the tiers 20 against the bottom of the hull 11. The tiers 20 nest together so as to reduce the height of the vehicle when the components are secured against each other for transport or storage.
[0064] FIG. 5B shows a detail of the tiers nested together. The uppermost tier 20a has a side beam 24a of each side that extends upwards to engage the corresponding side panel 13 of the float from below, and extends downwards to engage the corresponding side beam 20b of the middle tier 20b from above. The middle tier 20b is narrower in width so as to fit between the side beams 24a of the upper tier 20a. The middle tier has a side beam 24b on each side that extends upwards to engage the corresponding beam 24b of the upper tier from below on the inside, and extends downwards to engage the corresponding beam 24c of the lower tier 20c from above. The lower tier 20c is still narrower in width so as to fit between the side beams 24b of the middle tier 20b. The lower tier has a side beam 24c on each side that extends upwards to engage the corresponding beam 24b of the middle tier 20b from below on the inside, and extends downwards to provide a support leg for the entire vehicle to rest on when out of the water for transport or storage.
[0065] Thus, each tier is nested into the one above it by being narrower in width. The difference is about two times the thickness of the side beams, so that the side beam of each tier may engage the side beam of the tier above it. Since there is a close tolerance between the outermost side of the middle and lower tiers with the inside of the side beam of the tier above, the tiers are engaged one to another. Since there is a close tolerance between the inside of the top tier with the outer panel of the hull, the nested racks are engaged with the float. They may be secured in position by way of the tether winches, a lockable coupling mechanism, or both.
[0066] As an alternative nesting and engagement means, the nesting of the tiers may be done the other way up, so that the bottom tier is the widest, and the next tier is narrower to the extent required for the side beams to engage the side beams of the tier below it from the inside. As a third alternative, the tiers have substantially the same width, and nest by having side beams that splay downwards to fit over the tier below.
[0067] FIG. 6 shows two wave-powered water vehicles, each with three tiers of wings. The nesting allows the tiers to be packed closer together, reducing the height of the vehicle secured out of the water so that the two may be transported or stored one on top of the other in a standard sized metal shipping container.
Wave-Powered Vehicle Having an Opening for Dispensing a Payload or Equipment
[0068] In some instances, a wave-powered water vehicle of this invention may be wanted to dispense a large payload, or to lower equipment. For such purposes, the vehicle may be provided with a large opening (typically at or near the center of floatation) through which such payload or equipment may be dropped or lowered.
[0069] FIG. 7A shows such a vehicle in a perspective view from the lower right side.
There is a plurality of racks 20 comprising propulsion wings 22. The racks are shown drawn against the bottom of the float 10 by retracting the tethers 30 up. into the float each using a winch 32. All of the tiers of wing racks 20 and the bottom of the hull of the float 10 have been provided with openings 52 that substantially align downwards. This enables the user to deploy equipment 50 (such as monitoring or sensor equipment) or a payload through the hole either by dropping, or by lowering on a line 51 that extends from a winch 53 or lowering motor that is aboard the float.
[0070] FIG. 7B shows a detail of the vehicle in a perspective view from the upper right side. Here, three tiers of wing racks 20a, 20b, and 20c have been lowered to the downwards (propulsion providing) configuration using the tethers 30. Each of the three racks comprise an opening 52 made by omitting or cutting out a portion of the wings corresponding to the hole on each tier. Here, the wing racks are further stabilized and aligned above each other using guide wires 33 at the front and back of the racks. This helps align the opening in each rack 20 in rough seas so that the payload 50 may be passed on the line 51 directly through the holes 52 without substantially disturbing any of the racks.
Catamaran Style Wave-Powered Vehicles
[0071] FIGS. 8A, 8B, 8C, and 8D depict a wave-powered vehicle having a float comprising two floating elements or pontoons that track over the water in parallel one beside each other. FIG. 8A is a transverse cut-away view; FIG. 8B is a perspective from above showing solar panels on the top surface; FIG. 8C is a cut-away view down the middle; FIG. 8D is a perspective from below the rack of propulsion wings. The two pontoons are connected over the top, which provides a platform for mounting solar panels and electronic equipment. The cavity formed between the two pontoons provides a cavity that engages the swimmer from each side. Here, the swimmer is shown with a single wing rack, although multiple nesting wing racks can also be used. There are matching rudders at the end of each pontoon. In this example, there is also a propeller drawing power from a battery to provide locomotive power to the vessel when wave action is insufficient to drive the vehicle at the desired speed.
[0072] Figure 9 shows four catamaran-style wave-powered vehicles mounted on a truck. The vehicles are stored inside a shipping container mounted on a truck. In this drawing, the sides and top of the shipping container have been cut away to show the storage configuration. Sizing the swimmer or wing racks to be retractable between the two pontoons of each catamaran compacts the storage size. This allows four of the wave-powered vehicles to be stored and transported in a single standard-sized shipping container.
Spring; Arrangement for Controlling Wing Rotation with Gradations Of Torque
[0073] FIGS. 10A and 10B show a two-spring arrangement for controlling the movement of a fin, which is part of a wave-actuated component such as is shown in FIG. 2A. The spring arrangement constrains upward and downward rotation of the fins within two ranges requiring increasing torque. FIG. 10A is an upper perspective of the spring arrangement on the foremost fin or wing (not shown) to the right side beam 24 from behind on the inside, with the fm removed. FIG. 10B is an upper perspective of the same spring arrangement from behind on the outside, with the beam drawn transparently and showing a portion of the fm.
[0074] The fin is rotationally mounted to the side beam 24 by way of an axle 40 that passes transversely through the fin 22 just behind the leading edge 221 with the elevator portion of the fin 222 extending behind. The spring arrangement comprises a first and second springs 41 and 42. The first spring is wound around the axle 40 (shown in this example on the inside of the side beam 24. The first spring 41 extends from the axle at one end 411 to form a hook portion disposed to provide a point of attachment for the fin. In this embodiment, the other end of the first spring, not shown, is fixed to the side beam.
[0075] The second spring is also wound around the axle 40 in the same direction as the first spring 41. In this example, the second spring is thicker, and therefore stiffer, than the first spring. The second spring 42 extends from the axle at one end 424 to form a hook portion disposed to provide a point of attachment for the fin. The second spring 42 extends from the axle at the other end 424 to form a hook portion disposed to travel between an upper stop 422 and a lower stop 423 mounted on the side beam 24.
[0076] With this configuration, the first spring 41 is engaged to control the upward and downward rotational movement of the wing but the second spring is not- as long as the movement is within the range defined by the stops for the second spring. When the rotation of the wing goes beyond what is permitted by the stops, then the second spring 42 becomes engaged. As a consequence, the torque required to rotate the wing is now determined by both springs, and more torque is required to rotate the wing further in the same direction.
[0077] FIG. 11 is a graph showing the torque required to alter the angle of a wing of the vehicle in either direction from a neutral position. The torque required to operate the wing within the inner range is determined by the first spring alone, beyond which the torque required to alter the angle in either direction is determined by the combined torque of both springs.
Winch Design and Use
[0078] In another aspect of the invention, a WPD includes one or more winches (or their equivalent) that can store and release a tether before the WPD is launched, and/or can control the length of the tether when the WPD is in use, and/or can gather up the tether when the WPD is taken out of use, e.g., removed from the water completely. Preferably, when using a winch, the tether is free from electrical connections. If the tether does contain electrical connections, the winch system is more complicated. For example, the electrical connections will need to exit the center of the winch spool with slip rings or similar devices. Tethers without electrical connections may be thinner, enabling more wraps and greater length on the same diameter spool of a winch. Through the use of one or more winches, it is possible to obtain one or more of the following advantages:
(1) to optimize the distance between the float and the wave-actuated component,
depending on the actual expected wave and wind conditions (for example, longer to capture energy from slow, deep waves; shorter to reduce tether drag in high frequency wind chop).
(2) to reduce the distance between the float and wait-actuated component in order to get over under-sea obstacles or to release the swimmer if it is stranded in shallow water.
(3) to clean the tether, at regular or irregular intervals, by pulling the tether upwards through wipers, thus removing or reducing fouling which produces undesirable drag on the tether.
(4) to simplify deployment and recovery, particularly when the float and the wave- actuated component are designed so that they can be close to each other, e.g., in a nested configuration, for example when the float and the wave-actuated component can form a single tight bundle which is suitable for shipping and/or storage and which can be easily deployed into an operating condition in response to physical and/or electrical and/or electronic commands. (5) when there are two tethers, to remove twist by using the winch or winches to pull both tethers upward.
[0079] FIGS. 12A and 12B are drawings of a winch that may be used to raise and lower the tethers that attach the float to the swimmer or wing racks in a wave-powered vehicle of this invention. Typically, each tether has its own winch, which are coordinated to raise the swimmer simultaneously. FIG. 12A shows the winch with the cover closed. FIG. 12B is a perspective of the winch with the covering cut away to show what's inside. The tether 30 is rolled onto a spool 61 driven by a worm drive 63 attached to an electric motor 62. The tether winds and unwinds from the spool over a pulley 64 downwards through an opening 65 in the covering.
[0080] The tether 30 is flat and streamlined, so it will not flex easily in the pitch axis. A 160mm OD spool may support 10m of tether if the tether is 2mm thick. To allow the tether to pivot in pitch, the entire winch assembly is mounted on bearings at either end so that it pivots along a center axis 66. It has a cylindrical cover that is foam filled to displace water. The float will have a corresponding cylindrical opening so that minimum empty space is allowed to fill with water.
[0081] Wipers (not shown) are positioned in the winch assembly to clean slime and scum off of the tether before it is wound on the spool. This removes bio-fouling and may periodically be done to improve vehicle speed performance. The tether may include magnetic markers and magnetic sensors, such as hall effect sensors, may be positioned to measure movement of the tether. Alternatively, the tether may have variable magnetic permeability and a magnet may be one side of the tether as it enters the winch area while a hall sensor is on the other side. Since scum may change the effective thickness of the tether, this system can help maintain the correct deployed length. Multiple e.g., Dual Tethers
[0082] In another aspect of the invention, a WPD comprises a first tether that is attached (i) to the float at a first float location, and (ii) to the wave-actuated component (or swimmer) at a first swimmer location, and (2) a second tether that is attached (i) to the float at a second float location that is different from the first float location, and (ii) to the swimmer at a second swimmer location that is different from the first swimmer location, and the WPD has at least one of the following features (i.e., having one of the following features or a combination of any two or more of the following features):
(1) At least one of the tethers is secured to a winch secured to the float. In one
embodiment, both tethers are secured to the same winch. In another embodiment, one of the tethers is secured to a first winch and the other secured to a second winch. Optionally, the winch is mounted so that it can pivot along a center axis.
(2) The horizontal distance between the front of the float and the first float location is at most 0.3 times, preferably at most 0.2 times, e.g., 0.05-0.15 times, the horizontal length of the float.
(3) The horizontal distance between the rear of the float and the second float location is at most 0.3 times, preferably at most 0.2 times, e.g., 0.05-0.15 times, the horizontal length of the float.
(4) The horizontal distance between the front of the swimmer and the first swimmer location is at most 0.3 times, preferably at most 0.2 times, e.g., 0.05-0.15 times, the horizontal length of the swimmer.
(5) The horizontal distance between the rear of the swimmer and the second swimmer location is at most 0.3 times, preferably at most 0.2 times, e.g., 0.05-0.15 times, the horizontal length of the swimmer.
(6) At least one of the tethers has a substantially flat configuration, for example with an average thickness of 1 -3 mm, thus facilitating the handling of the tether, particularly when the tether is to be wound up on a winch. [0083] The use of dual tethers can reduce the likelihood that the tethers will become twisted; can enable a longer and narrower float shape (which reduces drag and increases speed); and by moving the connections and mechanisms associated with the tether to the fore and aft sections of the float, makes it possible to provide a larger central area of the float for payloads of all kinds, for example communications equipment and sensors and other scientific instruments. In addition, the use of two tethers can simplify recovery of a WPD. Recovering a WPD that has only a single tether can be difficult because pulling up on the single tether requires lifting the swimmer against the resistance of the fins to the water.
When there are two tethers, pulling on only one of the tethers tilts the swimmer and the fins attached to it so that the resistance of the fins is reduced. This is true, whether or not the WPD makes use of a winch to shorten the tether.
[0084] A WPD having a single tether generally has a tether termination assembly and load distribution structure at the center of the float, thus occupying the center of the float. The use of two spaced-part tethers frees up the center of float, which for many purposes is the most valuable part of the float desirable components. For example, the best part of the float for tall antennas is the center, where they can cast a shadow on at most half of solar panels mounted on the upper surface of the float (shading just part of a solar panel can completely disable it if, as is often the case, the cells are wired in series and shut off like transistors when dark.) Also, tall antennas have no steering effect on the float due to wind if they are at the center. When the WPD has two tethers, the center area of the float may be free for payloads with integrated antennas, i.e., antennas that are integrated with a dry box, or kept entirely within a dry area, thus reducing the danger that routing wires to the antennas will be damaged by moisture. In addition, placing most or all of the payload at the center of float makes it easier to balance the float fore and aft, and thus reduces the danger that the float will nose in or nose up.
[0085] When the WPD has two tethers, the float preferably contains a means to steer the float, such as a rudder at the tail end of the float. The wave-actuated component (swimmer) provides thrust as it is lifted and lowered due to wave action. Torque from the float is transmitted to the wave-actuated component by the separation of the two tethers. The wave- actuated component thus points in the same direction as the float after a steering lag, caused by the inertia and fluid resistance to rotation of the wave-actuated component.
[0086] In one configuration, there is a fore tether and an aft tether, preferably on a relatively long narrow float. While the tethers are taut, the wave-actuated component is held parallel with the float. Particularly when the wave-actuated component is held relatively level, a spring and stop system can control the angle of fins well, so that the fins operate at a favorable angle of attack during up and down motions with various speeds and amplitudes. The wave-actuated component can for example have a parallel bar structure with fin support shafts crossing between bars like ladder steps. The position of the fins can for example be controlled by a spring assembly that maintains the fins as a desired neutral position, e.g., a level position, when the springs are not moving and that will resist upward and downward motion. The spring profile may be adjusted so that the wings tend to stop at an angle that is optimized for maximum lift.
[0087] In another configuration, there are right and left tethers. These may connect to a single monolithic wing. The wing can move as a unit, pivoting at a point at which both the tethers are attached to the wing. A weight below the wing causes it to nose down and dive forward when lowered. The attachment point to the tethers is forward of the center of wing area so that the wing will nose up and pull forward when raised by the tethers. As in the fore- aft configuration the rudder that steers the float, also indirectly steers the glider by the separation of the two tethers.
[0088] In other configurations, 3 or 4 tethers may be used to stabilize the glider. This is useful especially in large systems. On the other hand, the presence of too many tethers is undesirable because each tether represents additional drag.
Communications and Control
[0083] FIG. 13 is a is a block diagram of a control system of the type that might be used in any of the WPDs discussed herein for directing the WPD along a desired path. This figure duplicates FIG. 5 in the above-referenced U.S. Patent No. 7,371 ,136.
[0084] FIG. 14 is a block diagram schematically showing a representative WPD's on-board electronics and some of the ways that the representative WPD communicates with outside entities. As mentioned above, the WPD uses satellite location systems and radio to communicate data back to an operator and to receive navigation and other commands, and has on-board computers and sensors that allow it to navigate or hold position autonomously, without regular human interaction or control.
[0085] The float contains core electronics including: satellite position sensor (GPS), radio communications (preferably sat-comm such as Iridium), an orientation sensing means such as a magnetic compass, batteries, navigation controller that uses information from the GPS and compass to control the rudder and steer the vehicle. The float may also include solar panels and various payload electronics such as environmental sensors or observation equipment such as radio monitors, cameras, hydrophones. All core electronics may be housed in the same enclosure, preferably at the tail end of the float. By keeping all the core electronics together, there is no need for wet connectors or cables in the core system. This is great reliability benefit, (solar panels and winches will connect with wet connectors - solar can be redundant so one connector can fail without taking the system down and winches are not necessary for basic functionality.) Since the GPS and sat-comm antennas are short, they will not shade the solar panels. Also the tail end is the least frequently submerged part of the float.(Submersion obscures the antennas.) however, as discussed above, with dual-tether embodiments, it is possible to house electronics and the like at the center of the float because the tether connections are near the end.
Terminology
[0086] The term "comprises" and grammatical equivalents (e.g., "includes" or "has") thereof are used herein to mean that other elements (i.e., components, ingredients, steps, etc.) are optionally present. For example, a water vehicle " comprising" (or "that comprises") components A, B, and C can contain only components A, B, and C, or can contain not only components A, B, and C but also one or more other components. The term "consisting essentially of and grammatical equivalents thereof is used herein to mean that other elements may be present that do not materially alter the claimed invention. The term "at least" followed by a number is used herein to denote the start of a range beginning with that number (which may be a range having an upper limit or no upper limit, depending on the variable being defined). For example "at least 1" means 1 or more than 1, and "at least 80%" means 80% or more than 80%. The term "at most" followed by a number is used herein to denote the end of a range ending with that number (which may be a range having 1 or 0 as its lower limit, or a range having no lower limit, depending upon the variable being defined). For example, "at most 4" means 4 or less than 4, and "at most 40%" means 40% or less than 40 %. When, in this specification, a range is given as " (a first number) to (a second number)" or "(a first number) - (a second number)," this means a range whose lower limit is the first number and whose upper limit is the second number. For example, "from 5 to 15 feet" or "5-15 feet" means a range whose lower limit is 5 feet and whose upper limit is 15 feet. The terms "plural," "multiple," "plurality," and "multiplicity" are used herein to denote two or more than two items. [0087] Where reference is made herein to a method comprising two or more defined steps, the defined steps can be carried out in any order or simultaneously (except where the context excludes that possibility), and the method can optionally include one or more other steps that are carried out before any of the defined steps, between two of the defined steps, or after all the defined steps (except where the context excludes that possibility). Where reference is made herein to "first" and "second" elements, this is generally done for identification purposes; unless the context requires otherwise, the first and second elements can be the same or different, and reference to a first element does not mean that a second element is necessarily present (though it may be present). Where reference is made herein to "a" or "an" element, this does not exclude the possibility that there are two or more such elements (except where the context excludes that possibility). Where reference is made herein to two or more elements, this does not exclude the possibility that the two or more elements are replaced by a lesser number or greater number of elements providing the same function (except where the context excludes that possibility). The numbers given herein should be construed with the latitude appropriate to their context and expression; for example, each number is subject to variation that depends on the accuracy with which it can be measured by methods conventionally used by those skilled in the art.
[0088] Unless otherwise noted, the references to the positioning and shape of a component of the vehicle refer to that positioning and shape when the vehicle is in still water. The terms listed below are used in this specification in accordance with the definitions given below.
[0089] "Leading edge" (or leading end) and "trailing edge" (or trailing end) denote the front and rear surfaces respectively of a fin or other component as wave power causes the vehicle to move forward.
[0090] "Fore" and "aft" denote locations relatively near the leading and trailing edges (or ends) respectively.
[0091] "Aligned" denotes a direction that lies generally in a vertical plane that is parallel to the vertical plane that includes the axial centerline of the swimmer. "Axially aligned" denotes a direction that lies generally in the vertical plane that includes the axial centerline of the swimmer.
[0092] "Transverse" denotes a direction that lies generally in a vertical plane orthogonal to the vertical plane that includes the axial centerline of the swimmer.
[0093] Where reference is made herein to a feature that "generally" complies with a particular definition, for example "generally in a vertical plane," "generally laminar," or "generally horizontal," it is to be understood that the feature need not comply strictly with that particular definition, but rather can depart from that strict definition by an amount that permits effective operation in accordance with the principles of the invention.
Conclusion
[0100] In conclusion, it can be seen that the embodiments of the invention provide structures and methods that can improve the handling of WPDs during storage, transport, launch, and recovery. [0101] In the Summary of the Invention and the Detailed Description of the Invention above, and the accompanying drawings, reference is made to particular features of the invention. It is to be understood that the disclosure of the invention in this specification includes all possible combinations of such particular features. For example, where a particular feature is disclosed in the context of a particular aspect, a particular embodiment, or a particular figure, that feature can also be used, to the extent appropriate, in the context of other particular aspects, embodiments, and figures, and in the invention generally. It is also to be understood that this invention includes all novel features disclosed herein and is not limited to the specific aspects of the invention set out above.
[0102] While the above is a complete description of specific embodiments of the invention, the above description should not be taken as limiting the scope of the invention as defined by the claims.
WO2013077931
WAVE-POWERED ENDURANCE EXTENSION MODULE FOR UNMANNED UNDERWATER VEHICLES
RELATED APPLICATIONS
[0001] For purposes of National and Regional Stage applications in all jurisdictions other than the U.S., this application claims the priority benefit of USSN 61/535,322 filed 15 September 201 1 ; USSN 61/535,1 16 filed 15 September 201 1 ; USSN 61/585,229 filed 10 January 2012; PCT/US2012/029718 filed 19 March 2012; PCT/US2012/029696 filed 19 March 2012; PCT/US2012/029703 filed 19 March 2012; USSN 13/424,239 filed 19 March 2012; USSN 13/424,170 filed 19 March 2012; USSN 13/424, 156 filed 19 March 2012; PCT/US2012/044729, filed 28 June 2012; and USSN 13/536,935, filed 28 June 2012.
[0002] For the purposes of the U.S. National Stage, all of the aforelisted patent applications are hereby incorporated herein by reference for all purposes except priority filing date, along with USSN 60/760,893, filed January 20, 2006; USSN 60/904,647, filed March 2, 2007; USSN 1 1/436,447, filed May 18, 2006, now U.S. Patent 7,371 , 136; USSN 12/082,513, filed April 1 1 , 2008, now U.S. Patent 7,641 ,524; USSN 60/841 ,834 filed September 1 , 2006; PCT/US2007/01 139, filed January 18, 2007, published August 2, 2007 as WO 2007/001 139; PCT/US2008/002703, filed February 29, 2008, published September 12, 2008 as WO 2008/109002; USSN 61/502,279, filed June 28, 201 1 ; and
USSN 61/574,508, filed August 2, 201 1.
[0003] For purposes of the U.S. National Stage, this application claims the priority benefit of the following three provisional applications: USSN 61/535,322 filed September 15, 201 1 ; USSN 61/535, 1 16 filed September 15, 201 1 ; and USSN 61/585,229 filed January 10, 2012.
FIELD OF THE INVENTION
[0004] The information disclosed and claimed below relates generally to the fields of vessel motility and autonomous operation. More specifically, it provides a module separate from an underwater vehicle that derives locomotive thrust from wave action and is capable of pulling the underwater vehicle between locations or through a current. BACKGROUND OF
THE INVENTION
[0005] Unmanned Underwater Vehicle (UUV) technology is currently under development for use in industry and the military. Autonomous devices are equipped to navigate under water without an operator on board, and without direct continuous input from a remote operator. Examples are illustrated in U.S. Patent Nos. 5,690,014 and 5,675,1 16 (U.S. Navy), and in 8,205,570 and D578,463 (Vehicle Control Technologies Inc.). Devices currently in production for civilian industrial use are the REMUS 600(TM), manufactured by Kongsberg Maritime in Kongsberg, Norway; the HarborScan(TM) UUV, manufactured by Vehicle Control Technologies Inc., Reston VA, U.S.A.; and the BlueFin(TM) model 12D, manufactured by Bluefin Robotics Corp., Quincy MA, U.S.A.
[0006] Another platform currently under development is the LDUUV (Large Displacement UUV) by the Office of Naval Research, Arlington VA, U.S.A. In a current embodiment, the LDUUV is approximately 20 feet long and weighs several tons, which limits its range and the durability of missions before maintenance or refueling. The Office of Naval Research has published the Navy research initiative ONR BAA 1 1 -025 describing future objectives of the UUV program.
[0007] A previously unrelated field of nautical technology is vessels that derive locomotive thrust from wave motion. As a wave travels along the surface of water, it produces vertical motion. The amplitude of the vertical motion decreases with depth; at a depth of about half the wave length, there is little vertical motion. The speed of currents induced by wind also decreases sharply with depth.
[0008] Various devices have been designed and proposed to harness wave power to do useful work. For example, U.S. Patent Nos. 986,627, 1 ,315,267, 2,520,804, 3,312, 186, 3,453,981 , 3,508,516, 3,845,733, 3,872,819, 3,928,967, 4,332,571 , 4,371 ,347, 4,389,843, 4,598,547, 4,684,350, 4,842,560, 4,968,273, 5,084,630, 5,577,942, 6,099,368 and 6,561 ,856; U.S. published applications US 2003/0220027 A l and US 2004/0102107 Al ; and international published applications WO 1987/04401 and WO 1994/10029.
[0009] Wave-powered vessels have been described in U.S. Patent 7,371 , 136; U.S. Patent 8,043, 133; and published applications US 2008/188150 A l ; US 2008/299843 Al ; and WO 2008/109022. Exemplary vessels are manufactured and sold by Liquid Robotics, Inc., Sunnyvale CA, USA under the brand Wave Glider<(R)>.
SUMMARY OF THE INVENTION
[0010] This disclosure provides a new approach and new technology for providing auxiliary thrust and/or power generation to an unmanned underwater vehicle.
[0011] An extension module (EXM) of this invention can be used with an underwater vehicle to provide a vessel combination with increased power durability and range of operation. One or more UUV tethers or other linkages interconnect the UUV with the EXM, thereby allowing the EXM to pull the UUV through a body of water, decreasing energy expenditure by the UUV. The tethers and couplings can also be configured so that the UUV can pull the EXM, for example, when the vessel combination is becalmed.
[0012] The EXM is any device or module that harvests horizontal thrust or propulsion directly or indirectly from wave motion. One such EXM comprises a float, a swimmer; and one or more EXM tethers connecting the float to the swimmer. The float is buoyed to travel on or near the surface of a body of water, and the swimmer is weighted to travel in the water below the float, hanging by the EXM tethers. The swimmer comprises fin surfaces that mechanically provide forward thrust when actuated by rising and falling of the swimmer in the water.
[0013] The EXM-UUV vessel combinations of this invention may also comprise a cradle configured for securing on or within the UUV and configured to receive the EXM. The EXM may be reversibly drawn to and secured upon or within the UUV in a retracted configuration by retracting the tethers, for example, by operating tether winches aboard the EXM or the UUV. Buoyancy of the float may be decreased when the EXM is retracted to the UUV, and increased when the EXM is deployed from the UUV. The EXM may be released from the cradle into a deployed or extended configuration by reversing the winches, thereby unpacking the EXM and positioning it to harvest wave motion and tow the UUV.
[0014] A UUV tether extended behind the EXM may be provided with a docking means by which the UUV may be joined to the EXM in a docked configuration, and released from the EXM in an undocked or independent configuration. The docking means typically has concave surfaces configured to accommodate and latch onto the front of the UUV, and is configured with vents to allow passage of water to decrease frontal drag when pulled by the EXM.
[0015] The EXM may be provided with a means for converting solar energy to electrical power and/or a means for converting wave motion to electrical power. The EXM may store the electricity and/or supply electrical power to the UUV.
[0016] Aspects of this invention include but are not limited to the EXM-UUV combination in a retracted or deployed configuration, a wave-powered vessel adapted for use as an EXM for tethering to a UUV, a cradle configured for securing on or within a UUV and configured to receive a wave-powered EXM when retracted thereto, and a tether configured for attachment to an EXM comprising a reversible docking means for a UUV.
[0017] This invention also provides a method of providing locomotive thrust to an unmanned underwater vehicle (UUV) by operating an extension module (EXM) that has been tethered to the UUV. The EXM is operated to derive locomotive thrust from wave motion, thereby pulling the UUV. In some instances, locomotive thrust of the EXM moves the UUV to a new location, or counters current flow so as to keep the UUV in substantially the same geographic location (referred to as hovering or loitering). Optionally, the motor or locomotion means within the UUV may be turned off while the UUV is being pulled by the EXM.
[0018] Where the UUV tether comprises a docking means for reversibly receiving the UUV, the UUV may detach from the UUV tether(s), locomote away from the EXM, and then reunite and reattach to the EXM by docking back to the docking means on the UUV tether(s). While attached or separate from the EXM, the UUV may perform a variety of commercially or militarily important missions, such as dispensing cargo or conducting measurements of the underwater environment.
[0019] Further aspects of the invention will be evident from the description that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIGS. 1A, IB, and 1C are front side perspectives of an Endurance Extension Module (above) combined with an unmanned underwater vehicle (below). FIG. 1A shows the EXM held in a cradle before installation onto the top surface of the UUV. FIG. IB shows the EXM and its cradle installed on and retracted onto the UUV. FIG. 1C shows the EXM deployed from the UUV. The EXM comprises a float and a swimmer, derives locomotive power from wave motion, and tows the UUV by way of two tethers.
[0021] FIG. 2 is a front side perspective of an EXM pulling a UUV by way of a single tether. The trailing end of the tether comprises a docking cone that conforms to and latches onto the front of the UUV.
[0022] FIG. 3 shows how water near the surface moves in roughly circular orbits that can be harvested to propel a vessel across the body of water.
[0023] FIG. 4 is a side view of a wave-powered vessel showing the principle of converting wave motion to locomotive thrust.
[0024] FIG. 5 is an elevated side view showing a detail of a working model in which a UUV (left) is tethered to the swimmer of an EXM (right).
[0025] FIG. 6 shows data from a demonstration in which the movement of a prototype EXM around a square course in the ocean (left) is compared with the movement of a prototype EXM towing a prototype UUV (right).
DETAILED DESCRIPTION
[0026] This invention provides an Endurance Extension Module (EXM) for powering an Unmanned Underwater Vehicle (UUV). The EXM converts wave motion to locomotive thrust, pulling the UUV from point to point or keeping it in place against an opposing current. The EXM may also supply the UUV with electricity for driving an electric motor or powering on-board electronics. The EXM can be retracted onto the UUV when not in use to minimize drag, or it can release the UUV for a subsequent rendezvous. The EXM- UUV combinations of this invention allow extended autonomous missions over wider territory for purposes such as surveying or monitoring conditions or delivering cargo.
[0027] FIGS. 1A, IB, and 1C depict an example in which the EXM works like a back pack that can be installed on a standard production UUV 61, thereby improving its loiter capabilities. It is a modular system where the EXM is carried on a cradle 51 that can be installed when needed, and removed or jettisoned when it is not needed. The EXM comprises a float 11, a swimmer 31, one or more lines or tethers 41a and 41b that connect the EXM to the UUV, and a retraction mechanism (not shown). Besides providing locomotive power, the EXM can provide a platform for generating electrical power, projecting one or more antennae for communication, and projecting one or more surface- based sensors, detectors, or cameras.
[0028] In this example, the float 11 supports solar panels 12 and an antenna 13. It contains flotation foam, or alternatively may contain adjustable buoyancy tanks such as air bladders that inflate. The swimmer 31 has fins 32 for converting wave motion to lateral thrust. When retracted, the EXM sits on top of the UUV 61 in a compact package with minimal frontal area 54 so that it has minor impact on drag. In the packed configuration, the UUV can operate at high speed and depth below reach of the connecting lines 41a and 41b, carrying the EXM like a back-pack for later deployment to resume hovering mode.
[0029] FIG. 2 depicts another example in which the EXM has a tether 41 with a docking nozzle or receptacle 42 configured for mating with the front of the UUV. This allows the UUV to detach from the EXM and sprint away to fulfill a mission, and then redock with the EXM in quiescent mode. The EXM comes into play during mission loiter periods, or during periods of slow transit, or after mission completion and prior to recovery. When deployed, the EXM provides propulsion and power regeneration capability as well as surface communications. These examples are discussed more extensively in a later section of this disclosure
Advantages
[0030] Depending on how it is configured, an EXM of this invention may provide the user with one or more of the following benefits:
- The EXM does not require and typically does not have any on-board solid, liquid, or nuclear fuel for locomotion. In a typical embodiment, wave power is converted mechanically to horizontal thrust, propelling the EXM through the water, which in turn tows the underwater vessel. Wave motion as a source of power is naturally occurring and inexhaustible.
- The EXM increases the endurance of an underwater vessel in the sense that it may be deployed for longer periods without refueling or servicing. This can increase the overall time and distance of a mission and the geographical range that may be surveyed or in which cargo may be deployed.
- The EXM enables an underwater vessel to adopt a hovering mode in the face of opposing current. Rather than using the resources of the motor and fuel cells aboard the underwater vessel, the EXM provides horizontal thrust to propel the vessel combination against the current to the extent needed to maintain the vessel in substantially the same geographical position. When the motor aboard the underwater vessel is not needed for propulsion, it may be turned off or secured to decrease wear and tear or attrition.
- The EXM can provide a source of renewable electrical power to the underwater vessel. As described below, electricity can be generated by solar panels atop the float and/or by harnessing wave motion, and then transmitted back to the vessel by an electrical connection associated with the tether, or by induction.
- The EXM can also provide a retractable surface platform for other activities, such as radio communication, surface or off-shore surveillance or monitoring, or surface cargo deployment.
Wave motion as an energy source for vessel propulsion
[0031] The EXM of this invention is a module separate from the UUV, and pulls the UUV in or through the water. The EXM derives some or all of its locomotive thrust from wave power. In principle, the wave power may be converted to electricity or other energy storage means, which can then be used to power a propeller or turbine. Usually for sustained use it is more efficient to convert wave motion directly by mechanical means to provide most or all of the horizontal propulsion.
[0032] FIG. 3 depicts in principle how wave motion can be approximated for many purposes as a linear superposition of roughly sinusoidal waves. The waves have varying wavelength, period and direction. As a wave moves horizontally along the surface, the water itself moves in roughly circular orbits of logarithmically decreasing diameter with depth. The vertical component, the horizontal component, or both may be harvested and converted into horizontal thrust for the purpose of propelling the vessel through the water.
[0033] Wave-powered vessels may be configured to exploit the motion between the tops and bottoms of waves at the sea surface in the following way. A vessel body is positioned at or near the surface, a submerged swimmer or glider component is positioned underneath, and connected to the vessel body by one or more tethers. As waves lift and lower the float portion, wings or fins on the submerged swimmer passively rotate so as to convert the relative motion of the surrounding water into forward thrust. The azimuth of the thrust vector can be directed completely independently of the direction of the waves by a rudder at the back of the swimmer. The wings have a short chord dimension to minimize lost motion between the up stroke and the down stroke, converting even very small waves into forward thrust.
[0034] FIG. 4 is an upper side view of a wave-powered vehicle that illustrates this design. The vehicle comprises a float or vessel body 11 resting on the water surface, and a swimmer 31 hanging below, suspended by one or more tethers 21. The float 11 comprises a displacement hull 16 and a fixed keel fin 15. The swimmer comprises a rudder 34 for steering and wings or fins 32 connected to a central beam 33 of the rack so as to permit rotation of the wings around a transverse axis within a constrained range, and provide propulsion. The tethers 21 may be attached at either end by way of a winch 22 for retracting the swimmer 31 up to the float 11 for purposes of storage or navigational adjustment and then deploying the swimmer 31 downwards for full operation.
[0035] In still water (shown in the leftmost panel), the submerged swimmer 31 hangs level by way of the tether 21 directly below the float 11. As a wave lifts the float 11 (middle panel), an upwards force is generated on the tether 21, pulling the swimmer 31 upwards through the water. This causers the wings 32 of the swimmer to rotate about a transverse axis where the wings are connected to the rack 33, and assume a downwards sloping position. As the water is forced downward through the swimmer, the downwards sloping wings generate forward thrust, and the swimmer pulls the float forward.
[0036] After the wave crests (rightmost panel), the float 11 descends into a trough. The swimmer 21 also sinks, since it is heavier than water, keeping tension on the tether 21. The wings 32 rotate about the transverse axis the other way, assuming an upwards sloping position. As the water is forced upwards through the swimmer, the upwards sloping wings generate forward thrust, and the swimmer again pulls the float forwards. Thus, the swimmer generates thrust when both ascending and descending, resulting in forward motion of the entire craft.
[0037] As an alternative to the float and swimmer combination, other wave powered vessel designs can be adapted for use as an EXM. By way of illustration, the vessel may comprise dual fins set in a side-by-side configuration beneath the bow. The fins convert wave energy into a dolphin-like kick that can propel a load of up to three tons at five knots. See Popular Mechanics magazine, October 2009. Alternatively, wave powered vessels may incorporate an adjustable sail and keel for aerodynamic and hydrodynamic shear force resolution for directional thrust. US 2009/0193715 Al . See also U.S. Patent 4,842,560, wave powered propulsion system for watercraft; U.S. Patent 7,955,148, hydroelectric turbine-based power-generating system for vessels; and U.S. Patent 6,814,633, wave powered vessel.
Using an EXM to provide locomotive power to a UUV.
[0038] In its minimum configuration, an EXM-UUV combination of this invention will typically comprise two components: (1 ) an underwater component that is capable of travelling and operating without a human on board and without being attached to the EXM; and (2) the extension module that provides locomotive power to pull or drive the UUV across or through the water when desired instead of or as well as the UUV's on-board propulsion mechanism. The EXM derives part or all of its locomotive thrust from wave motion, either mechanically, or by conversion to and from an energy storage means such as electrical, gravitational, or chemical potential, or a combination of both direct mechanical conversion and through a storage means.
[0039] Referring to FIG. 1A, an underwater vessel 61 is depicted as having a hydrodynamically shaped nose or front 62, a substantially cuboid body 63, rear fins 64 for promoting even travel, and a propeller 65 or turbine for providing locomotive thrust when the vessel is operating by itself. The EXM-UUV configuration may be created by joining and securing an EXM carried by a cradle 51 on or within an underwater vessel 61 in a permanent or detachable manner.
[0040] Here, the cradle 51 is configured underneath to mate with the upper surface of the vessel 61. Lying on top of the cradle 51 is the EXM comprising the float 11 and the swimmer (hidden beneath the float in this view). The float is depicted as having solar panels 12 on its upward-facing surface for producing electricity and an antenna 13 for wireless communication when the float is above the water. The cradle 51 is adapted on its upper surface to accommodate the swimmer and the float in compact retracted configuration. As an alternative, the vessel can be engineered from the outset to conform substantially to and thereby receive the EXM directly when the two are retracted together. The advantage of the cradle 51 is that it allows the EXM to be installed on a standard production UUV. The means of securing the cradle to the UUV can be selected so that the cradle may be affixed permanently, or so that it can be released or jettisoned under water, for example, to free up the UUV for a particular operation, or to create a decoy.
[0041] In FIG. IB, the cradle 51 carrying the EXM is shown retracted onto the surface of the underwater vessel 61 to provide a configuration that is the most compact and protective. This conformation may be adopted for storage of the combination on land or for hydrodynamic travel under water.
[0042] FIG. 1C shows the combination when deployed in a body of water with the EXM positioned to tow the underwater vessel 61.
[0043] The EXM comprises the float 11 and the swimmer 31 which work together to convert wave motion to horizontal thrust. The swimmer 31 shown here is depicted as having a rack with a single central spine or beam 33 upon which the fins or wings 32 are mounted. In other configurations, the rack may have outer rails, with one, two, or more than two rows of fins. A single rack facilitates retraction onto the cradle, but there may be multiple racks configured for nesting. As before, the fins rotate over a limited range about an axis that is horizontally perpendicular to the rail so as to provide forward thrust as the swimmer 31 travels up and down as a result of wave action on the float 11. In this example, the float 11 is joined to the swimmer 31 by way of two EXM flexible or rigid tethers that are mounted fore 21a and aft 21b. A plurality of tethers may be used in an EXM in preference to a single tether, so that the float 11 and swimmer 31 may track more closely together.
[0044] Winch systems to retract tethers 21a and 21b can be mounted on the float 11 or the swimmer 31. Winch systems to retract tethers 41a and 41b can be mounted on the swimmer 31, the cradle 51, or directly on the UUV 61. Alternatively, in either case, by placing a winch at the middle of each tether for winding both ends, slip rings can be eliminated for the power and communications lines that deploy alongside one or more of the tethers.
[0045] The cradle 51 is depicted here as having a substantially flat surface 52 configured to mate with the EXM. A groove 53 down the center may be provided to promote the range of motion or retractabihty of the EXM. The cradle has a leading edge 54 that is designed to make both the cradle and the EXM frontally hydrodynamic when the EXM is retracted, thereby minimizing or substantially lowering hydrodynamic drag when the vessel 61 is being propelled by the onboard propeller 65. Depending on the dimensions and speed of the vessel, drag may be reduced so that the additional power needed to propel the vessel with the EXM on board is no more than about 20%, 10%, or even 5% of the power needed without the EXM or cradle attached.
[0046] The EXM is attached to the vessel by way of a fore 41a and aft 41b UUV tether between the swimmer 31 and either the float 51 or the vessel itself 61. The tethers are compliant so as to decouple heave motions of the EXM from the UUV, decreasing form drag effects. Two or a plurality of UUV tethers keep the components in yaw, again promoting unified tracking and steerability. The vessel 61 will typically have its own rudder so as to be steerable when not operating with the EXM. The EXM may also have a rudder attached either to the float 11, the swimmer 31 or both so as to provide steering when the EXM is towing the underwater vessel. Where multiple rudders are present, they may be controlled and coordinated by an on-board microprocessor.
Deploying the EXM from the UUV
[0047] When the EXM is packed into a cradle atop the UUV as in FIGS. 1A and IB, it may be deployed as follows. The UUV will typically surface first, and confirm appropriate surface conditions exist for deployment. It will then activate the EXM by unlatching the restraints and allowing the connecting lines to pay out from the retraction winches. The float will remain at the surface where will be coupled to the ocean surface and will move up and down with the waves. The swimmer hangs below the float by 1 -20 meters (typically 4- 8 meters) and will be pulled up and down through relatively still water. Wings on the swimmer pitch up and down, to generate thrust during both the up and down motions of the float, the tethers between the UUV mounting structure and the swimmer allows the swimmer to move up and down while the UUV remains at a relatively constant depth.
[0048] Once deployed, the UUV may steer the entire system using its existing rudder. In addition or instead (for example, if the UUV uses directional thrusters for steering) then a rudder may be installed on the float and/or the swimmer.
[0049] Depending on conditions and their operational capabilities, the EXM and UUV may be operated in other configurations. For example, when seas are becalmed or when the wave harvesting mechanism of the EXM is inoperative, the EXM may be retracted back onto the cradle or onto the UUV. Alternatively, in such circumstances, it may be desirable to leave the EXM on the surface, for example, to harvest solar power, maintain
communications, or continue operation of surface-mounted sensors. In this case, the UUV may contribute to or be solely responsible for any locomotion of the EXM-UUV combination (for example, for traveling to a new location or for hovering against an oncoming current). The components thus reverse their more usual roles, with the UUV traveling in front and pulling the EXM by way of the interconnecting tethers.
Dockable combinations
[0050] For some missions, the UUV may be equipped to be reversibly detachable from the EXM while in operation. With this in place, the UUV may detach from the EXM in order to sprint to a new location for a particular activity. It may then navigate back to and dock with the EXM at the old location, the new location, or elsewhere as conditions permit.
[0051] FIG. 2 depicts an embodiment that facilitates operation in this fashion. The EXM is joined to the UUV by way of a single UUV tether or tow line 41 from the back of the swimmer 31 to a docking means 42 in which the vessel 61 may dock and be secured for towing. In this example, the docking means 42 is substantially cone shaped, configured with substantially concave shapes on the inner surface of the cone to mate with the substantially convex outer surface of the front or nose of the vessel 61. In this example, the docking means is also rendered more hydrodynamic by providing a plurality of vents for allowing the passage of water through the cone when not towing the vessel. Not shown are mechanical or magnetic couplers that secure the vessel 61 to the docking means 42 with a robustness sufficient to sustain the linkage during towing.
[0052] In operation, the vessel 61 detaches from the docking means 42 mounted at or near the aft end of the UUV tether 41, operates a self-contained locomotion means such as a propeller 65 so as to travel away from the components of the EXM 11 and 31, optionally dispenses cargo or conducts measurements of the underwater environment in which the UUV is traveling, and then reunites and reattaches to the EXM by docking back to the docking means 42.
Electricity Generation
[0053] In addition to or instead of its role of towing the UUV, an EXM of this invention may serve the function of generating and optionally storing electrical energy.
[0054] As shown in FIG. 1, a portion of the EXM that floats upon the water surface upon deployment from the UUV may be equipped with commercial grade photovoltaic cells, such as those manufactured by SunPower Corp., San Jose CA, U.S.A. Two solar panels each with an area of approximately 4.5 ft<2> can provide 10-13 Watts on average at mid- latitudes, corresponding to roughly 250 to 300 Watt hours harvested every day.
[0055] As an alternative or in addition to solar panels, the EXM may be equipped with a means whereby wave power may be harvested and converted to electricity. This is further described in PCT/US2012/044729, which is hereby incorporated herein by reference. When wave motion is sufficiently high, enough power can be harvested not only to propel the vessel through the water, but also to provide ample electrical power.
[0056] Wave power can be converted to electricity directly by configuring the vessel so that the vertical undulations of the vessel are mechanically coupled to an electrical generator. As shown in PCT/US2012/044729, spring-loaded swing arms can be mounted on the float and connected to the tethers suspending the swimmer. Some of the wave motion is harvested as potential energy in the spring, which can then be converted to electrical power. Motion of the swing arms ultimately results in a mechanical force turning conductive wire or bar within a magnetic field, or turning a magnet through a conductor, thereby generating electricity.
[0057] Another way of converting wave motion to electrical power is to harvest the horizontal movement of the water resulting from wave-powered locomotion. For example, a propeller or turbine may be oriented forwards or rearwards to harvest vertical movement through the water, and mechanically coupled to a rotating magnet conductor arrangement that plays the role of generator. The user has the option of configuring the generator to play a reverse role, being caused by electrical power to rotate in the opposite direction, thereby rotating the propeller or turbine so as to generate thrust. In this arrangement, the propeller generator system may be installed on the swimmer of the EXM, on the UUV, or both.
[0058] Harvested electrical power may be used to power electronics, charge a battery, or drive a motor for propulsion aboard the EXM. By electrically coupling the EXM to the UUV (for example, by a wire traveling through or near one of the tethers or wirelessly by electromagnetic induction or electrodynamic induction), the EXM can supply electricity to the UUV to power electronics, charge a battery, or drive a motor for propulsion aboard the UUV. Buoyancy and navigation
[0059] Buoyancy of the UUV and the EXM may be chosen or adapted during operation, depending on the mission requirements.
[0060] In one approach, the EXM (as a whole) is positively buoyant while the UUV is made negatively buoyant. This approach is best suited for an integrated EXM, where the UUV will not be required to operate with the EXM jettisoned. The negative buoyancy of the UUV can then be used to provide a downward pull on the swimmer such that it generates thrust during the down phase of motion. When retracted, the float may replace buoyancy components (often syntactic foam) that would normally be installed in the upper portion of the UUV to provide stability. This approach minimizes overall system displacement and thus drag.
[0061] In another approach, the EXM is neutrally buoyant. In this case it can be installed as a completely independent module. It may be installed on a UUV with minor modification, and may be jettisoned without requiring the UUV to make major adjustments to its buoyancy. The drawings show an EXM that is neutrally buoyant attached to an approximately neutrally buoyant UUV. If jettisoned, the EXM could swim autonomously to a collection location or act as a decoy while the UUV carries out a sub-surface mission.
[0062] If appropriate, buoyancy of the EXM and/or the UUV may be made adjustable to adapt to operating conditions and objectives (for example, by expanding or compressing an inner cavity or releasing compressed gas). For example, the buoyancy of the float may be made adjustable so that buoyancy may be decreased when the EXM is retracted to the UUV, and increased when the EXM is deployed from the UUV. This can facilitate deployment of the EXM from its cradle and operation of the vessel combination following deployment.
[0063] For self-directed navigation, the EXM-UUV combination may be equipped with a means of determining the geographical location of the vessel, a means for determining direction, a means for steering the vessel, and a means for operating the steering so that the vessel travels or stays at a target location. Electronics to sense the geographical location of a vessel can triangulate off a series of reference points. For example, the float may be equipped with a GPS receiver, and either the EXM or the UUV can be equipped with an electronic compass or gyroscope to determine the vessel heading. Positional data about the geographical location and the vessel heading is processed in a decision algorithm or programmed microprocessor aboard the EXM or the UUV, which may then provide navigation instructions. Consequently, the rudder or steering means adjusts to head the vessel in accordance with the instructions.
[0064] When the EXM has at least one component that rides at or near the water's surface, it provides a platform for equipment of special use to the UUV. These include: (1) GPS positional receivers and other navigational equipment; (2) such detectors and sensors that operate beneficially at or near the surface (for example, to determine items, parameters, or activity in the atmosphere, by a surface-going vessel, or at an on-shore location); (3) wireless transmitters and receivers for radio communication (for example, to receive navigational instructions, mission parameters, or other commands, and to transmit data collected from detectors or sensors aboard the EXM and/or the UUV); and (4) batteries and storage capacity to supplement the capabilities of the UUV.
Proof of Concept
[0065] Predictive modeling indicated that in the deployed configuration, the EXM's wave propulsion system can reduce the total energy required to conduct a threshold mission profile by a UUV by 55%. The EXM's solar panel array can harvest an additional 24% of the total energy requirement, resulting in a reduction of the objective mission profile's energy requirement by 79%. When the EXM is stored in a cradle aboard the UUV, it should have minimal impact on UUV sprint speed. Assuming that the EXM system is 9 inches tall and 4 feet wide when on top of the UUV, the additional frontal area is predicted to cost a modest 5.5% reduction in top speed. If the height of the stowed EXM is 12 inches, then the top speed would be reduced by 7.7% to roughly 1 1.25 knots. The decreased vessel speed would be more than offset by the increased range and mission duration that the EXM provides.
[0066] FIG. 5 shows a replica of the autonomous underwater vessel REMUS(TM) 600. FIG. 6 shows results of a towing test using a mass model in place of a UUV. The mass model was a 10 feet long section of 24" diameter PVC tube 61. A hemispherical nose 62 was mounted to the front of the tube and the tail was left open. The tube was free flooded, with buoyancy provided by a smaller sealed tube mounted inside. The mass model was trimmed to be approximately 1 lb. negatively buoyant. The open tail created vortex as it moved through the water, resulting in higher drag than a closed UUV with contoured fairing.
[0067] An eight-foot long three-point bridle 43 with an eight-foot leader 41 was attached to the keel of the swimmer slightly aft of center. No attempt was made to optimize the tow- point configuration on the mass model. The buoyancy of the mass model was adjusted to achieve stable and level travel behind and slightly below the swimmer. The mass model and the water it entrained had a combined mass of 3640 kg. The leader 41 was used for attaching a prototype wave-powered EXM, comprising a swimmer 31 attached by way of an EXM tether 21 to a float (not shown).
[0068] FIG. 6 compares the speed of a prototype EXM towing a mass model (right side) with a structurally and functionally equivalent prototype EXM travelling alone. They simultaneously raced adjacent 0.5 km square courses, thereby experiencing substantially the same sea conditions: 1 to 3 feet waves and 10 knot winds. Both the uncoupled EXM and the EXM pulling the mass model were able to navigate the course in good order. The speed of the EXM towing the mass model was 44% slower. This validates the utility of a wave- powered EXM for towing a UUV. Since the square course was short and the EXM slows during each turn, the reduction in speed was more than would typically occur in a typical patrolling scenario without frequent turns.
[0069] Drag and tow-bar pulling (drogue drag) forces increase with the cube of the scale factor. These forces balance out so that vessel speed is relatively insensitive to scale.
Scaling up by a factor of three, the EXM should tow a 72" diameter tube with similar performance. With an EXM having an average speed of 1.5 knots, the 72" diameter tube would tow at a speed of 0.84 knots. Performance may be improved by providing fairing on the UUV so that it is more hydrodynamic when being pulled by the EXM, while carrying the EXM, or both.
[0070] Wave-powered vessels and modules are highly responsive and robust to extreme weather conditions. This was demonstrated when a Liquid Robotics brand Wave Glider<(R)> designated "G2" was encroached by hurricane Isaac in the summer of 2012. Isaac had sustained winds of 40 knots with gusts up to 74 knots and a low barometric pressure of 988.3 millibars. G2 had been outfitted with sensors to measure water temperature, wind speeds, barometric pressure, and air temperature. The eye of the storm passed 60 miles to the east of G2, which rode out the storm and collected sensor data that provided new insights into hurricane activity. Time-lapsed maps showed a considerable drop in water temperature, suggesting that Isaac was vacuuming heat from the ocean surface.
Glossary
[0071] The terms "vessel", "watercraft", and [sea going] "vehicle" are used
interchangeably in this disclosure to refer to a nautical craft that can travel across and about any body of water at, near, or below the surface.
[0072] A "wave-powered" vessel or device derives at least a majority of its power for locomotion or electricity generation from motion of the water at or about a point of reference. Optionally, the vessel may also derive power from solar energy and other natural sources, and/or man-made sources such as batteries and liquid fuel powered engines. In this context, a "wave" is any upward and downward or side-to-side motion of the water at a point of reference on or near the surface (such as the center of flotation of a vessel).
[0073] A "vessel body" or "float" is a component of a vessel that travels on or near the surface of the water. It may have its own source of locomotive power and/or rely on being pulled by a submarine component. When configured to harness wave power, it has an overall density that is lighter than water.
[0074] A "swimmer", "pod", "submarine component", "sub", "glider" or "wing rack" is a component of a vessel that travels below the surface of the water and below the vessel body, to which it provides locomotive power or propulsion. The swimmer may be equipped with a plurality of "fins" or "wings" that rotate upwards or downwards around an axle transverse to the direction of travel. Vessels may be configured with one multiple swimmers, typically joined to the same two or more tethers at different depths, each providing locomotive thrust in response to wave action, and optionally configured for nesting when retracted (PCT/US2012/029696). Thus, all the aspects of this invention deriving wave power from a swimmer includes or can be adapted mutatis mutandis to include two, three, or more than three swimmers or wing racks.
[0075] An "underwater" vehicle is a vessel designed for traveling under the surface of a body of water to conduct certain activities. It is so classified while actually under the water, when on the surface, or on shore awaiting deployment.
[0076] An "extension module" or "endurance extension module" (EXM) is a separate module tethered or otherwise attached to a self-propelling vessel for purposes of providing additional or supplementary propulsion, for providing electricity, or both.
[0077] An "unmanned" underwater vehicle, EXM, or other vessel or vessel combination is designed and configured to travel in most circumstances across or through a body without the need of a human on board (whether or not a human is present). Either alone or in combination with modules tethered thereto, it has a self-contained source of locomotive power.
[0078] An "autonomous" underwater vehicle, EXM, or other vessel or vessel combination is self-guiding in its operation without needing a human on board or in constant active control at a remote location. Navigation may be controlled by a combination of sensors, electronics, and microprocessors aboard or at a remote location and in wireless communication with the vessel, in combination with periodic or occasional human or remote microprocessor input to set course or mission parameters.
[0079] In the context of this disclosure, a "cradle" is a device component configured for securing on or within a UUV on one surface, and configured to receive an EXM on another surface. The cradle may have any shape that is consistent with this function.
[0080] For all purposes in the United States of America, each and every publication and patent document cited herein is incorporated herein by reference as if each such publication or document was specifically and individually indicated to be incorporated herein by reference.
[0081] While the invention has been described with reference to the specific
embodiments, changes can be made and equivalents can be substituted to adapt to a particular context or intended use, thereby achieving benefits of the invention without departing from the scope of what is claimed.
US2013059488
AU2012275286
Watercraft that harvest both locomotive thrust and electrical power from wave motion
This disclosure provides improved nautical craft that can travel and navigate on their own. A hybrid vessel is described that converts wave motion to locomotive thrust by mechanical means, and also converts wave motion to electrical power for storage in a battery. The electrical power can then be tapped to provide locomotive power during periods where wave motion is inadequate and during deployment. The electrical power can also be tapped to even out the undulating thrust that is created when locomotion of the vessel is powered by wave motion alone.
RELATED APPLICATIONS
[0001] This application claims the priority benefit under 35 U.S.C. $119(e) of the following U.S. provisional patent applications:
U.S. Provisional Patent Application No. 61/502,279: "Energy-harvesting water vehicle," filed Jun. 28, 2011;
U.S. Provisional Patent Application No. 61/535,116: "Wave-powered vehicles," filed Sep. 15, 2011; and
U.S. Provisional Patent Application No. 61/585,229: "Retractable nesting wing racks for wave-powered vehicle," filed Jan. 10, 2012.
[0005] This application also claims the priority benefit of the following patent applications, all filed Mar. 19, 2012 and co-owned with this application by Liquid Robotics, Inc., Sunnyvale, Calif., U.S.A.:
International Patent Application No. PCT/US2012/029718 and U.S. patent application Ser. No. 13/424,239, both entitled "Autonomous wave-powered substance distribution vessels"
International Patent Application No. PCT/US2012/029696 and U.S. patent application Ser. No. 13/424,170, both entitled "Wave-powered vessels configured for nesting"; and
International Patent Application No. PCT/US2012/029703 and U.S. patent application Ser. No. 13/424,156, both entitled "Wave-powered device with one or more tethers."
[0009] The aforelisted priority applications, along with U.S. Pat. No. 7,371,136; U.S. Pat. No. 8,043,133; and published applications US 2008/188150 A1; US 2008/299843 A1; and WO/2008/109022 are hereby incorporated herein by reference in their entirety for all purposes.
FIELD OF THE INVENTION
[0010] The information disclosed and claimed below relates generally to the fields of vessel motility and power generation. More specifically, it provides watercraft configured for autonomous operation, harvesting both locomotive thrust and electrical power from wave motion.
BACKGROUND OF THE INVENTION
[0011] Wave-powered vessels have been described in U.S. Pat. No. 7,371,136; U.S. Pat. No. 8,043,133; and published applications US 2008/188150 A1; US 2008/299843 A1; and WO/2008/109022. Exemplary vessels are manufactured and sold by Liquid Robotics, Inc., Sunnyvale, Calif., USA under the brand Wave Glider(R).
[0012] A previously unrelated field of development covers large stationary systems near shore that use wave motion to generate electrical power for communities on land. U.S. Pat. No. 4,134,023 discusses an apparatus for extracting energy from waves on water. U.S. Pat. No. 6,194,815 provides a piezoelectric rotary electrical energy generator. Published application US 2004/0217597 A1 discusses wave energy converters that use pressure differences. U.S. Pat. No. 3,928,967 is the so-called "Salter's Duck" patent, an apparatus and method of extracting wave energy. The status and perspectives of wave energy technology is generally reviewed by Clément et al. in Renewable and Sustainable Energy Reviews 6 (5): 405-431, 2002.
SUMMARY OF THE INVENTION
[0013] This disclosure provides improved technology for manufacturing and deploying nautical craft that can travel and navigate on their own. A hybrid vessel is described that converts wave motion to locomotive thrust by mechanical means, and also converts wave motion to electrical power for storage in a battery. The electrical power can then be tapped to provide locomotive power during periods where wave motion is inadequate and during deployment. The electrical power can also be tapped to even out the undulating thrust that is created when locomotion of the vessel is powered by wave motion alone.
[0014] One aspect of the invention is a wave-powered vessel that has a buoyant vessel body, a mechanical means for converting movement of the vessel body caused by wave motion to horizontal thrust; and an electrical generator for converting movement of the vessel body caused by wave motion to electrical power. Converting wave motion to horizontal thrust may be done in a configuration where an underwater component or swimmer is attached below the vessel body by one or more tethers. In this configuration, the swimmer is weighted to travel in water below the vessel body, and is configured to pull the vessel body by way of the tether. The swimmer has fin surfaces that mechanically provide forward thrust when actuated by rising and falling of the swimmer in the water.
[0015] The on-board electrical generator may comprise a means for converting vertical movement of the vessel body caused by wave motion to electrical power, a means for converting horizontal movement of the vessel body through water to electrical power, or both. Shown in the figures is a wave-powered vessel where the electrical generator comprises a piston powered by a swing arm that moves from a horizontal to a vertical position in accordance with the vertical movement of the vessel body. The swing arm is mechanically connected to a swimmer weighted to travel in water below the vessel body. Optionally, the swimmer may be adapted so that motion of the fin surfaces may be dampened to increase electrical power generated by the electrical generator.
[0016] Another type of electrical generator comprises a rotatory fin or turbine powered by horizontal movement of the vessel body through the water. In this case, the rotatory fin or turbine is adapted to generate electrical power when rotated in one direction, and to act as a motor providing horizontal thrust to the vessel through the water when rotated in the opposite direction. Further types of electrical generators for harnessing swave powers are detailed later in this disclosure.
[0017] Wave-powered vessels according to this invention typically have an electrically powered motor to provide horizontal thrust that powers the vessel through the water. There is also a battery configured to store electrical power generated by the electrical generator and to feed electrical power to the motor to provide propulsion. Optionally, the vessel may have one or more solar panels that also supply electrical power to the battery.
[0018] The battery may be used to power an inboard or outboard electrical motor at any time there is reserve electrical power and it is desirable to increase the sped of the vessel. For example, the battery can power the motor during periods where the motion in each full wave cycle is inadequate to provide sufficient horizontal thrust to the vessel.
[0019] Another aspect of the invention is a wave-powered vessel with locomotive thrust powered alternately by wave motion and by electrical power so as to buffer the trust powered by the wave motion. The electrical power is supplied by a battery, which in turn is charged up by a system that converts wave motion to electrical power, as already outlined.
[0020] Another aspect of this invention is a wave-powered vessel configured for deployment from shore. The vessel is kept in compact form, and launched by way of the electric motor to deeper water, whereupon the other components of the vessel are deployed outward and downward. A vessel of this nature typically has a buoyant vessel body, a swimmer configured to retract and be secured against the vessel body, one or more tethers connecting the float to the swimmer, an electrically powered motor configured to propel the vessel through the water; and a battery supplying power to the motor, having sufficient capacity to power the vessel from shore to a location where the swimmer can be deployed. Again, the swimmer is weighted to travel in the water below the vessel body, and is configured with fins to pull the vessel by way of the tether when actuated by vertical movement.
[0021] Such a vessel may also have a releasable tow buoy. The vessel body and the tow buoy are configured so that the tow buoy may be releasably housed within the vessel body while on shore, and pulled behind the vessel body after the vessel is deployed.
[0022] The vessels of this invention are ideal for use in autonomous operation (without a human attendant on board). The vessel has electronics configured to sense the geographical location of the vessel. There is also a microprocessor programmed to determine the vessels current location, and steer the vessel from its current location towards a target location.
[0023] Further aspects of the invention will be evident from the description that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1A shows how water moves in roughly circular orbits in waves;
[0025] FIG. 1B is a side view of a wave-powered vehicle showing the overall operation;
[0026] FIG. 2 shows an example of an algorithm for directing a vessel towards or maintaining it at a target position (a geographical location);
[0027] FIG. 3 shows the availability of solar power as a function of the annual cycle;
[0028] FIG. 4 is a block diagram summarizing how the interaction of power sources can occur;
[0029] FIG. 5A, FIG. 5B, FIG. 6A, and FIG. 6B are side views of a vessel that illustrates how wave motion can be converted to electrical power;
[0030] FIG. 7, FIG. 8A, and FIG. 8B show an example of a vessel that uses wave motion to generate both locomotive thrust and electrical power from vessel motion;
[0031] FIG. 9 is a graph of hypothetical data that illustrates how stored electrical power in the battery can be used to power the electric motor and provide propulsion whenever desired; and
[0032] FIG. 10 is a perspective view showing how a vessel body and a tow buoy may be configured so that the tow buoy may be releasably housed within the vessel body while on shore, and pulled behind the vessel body after the vessel is deployed.
DETAILED DESCRIPTION
[0033] This invention provides watercraft that derive both locomotive thrust and electrical energy by wave motion. Detailed illustrations of the invention include a vessel that harvests the power of vertical movement using tethers attached to a spring-loaded suspension device. Wave energy is converted to potential energy in the springs, which is then used to drive an electricity generator. In another example, the vessel has a propeller that can be driven backwards as a generator when in motion so as produce electrical power. Electrical energy obtained by either of these means may be used to power electronics or stored in a battery for later use. The stored energy can be used to provide propulsion on calm days when wave action does not in itself provide enough power for the vessel to travel at the desired speed.
Converting Vertical Wave Power to Locomotive Thrust
[0034] One feature of the watercraft of this invention is the ability to use wave motion to drive the vessel from place to place across a body of water.
[0035] Wave motion can be approximated for many purposes as a linear superposition of roughly sinusoidal waves of varying wavelength, period and direction. As a wave moves horizontally along the surface, the water itself moves in roughly circular orbits of logarithmically decreasing diameter with depth. This is shown in FIG. 1A. The orbit at the surface has a diameter equal to the height of the wave. The orbital diameter at depth is a function of wave length:
[0000]
Hy=Hse<-2[pi]y/L >
[0000] where L is the wave length, Hs is the surface wave height and Hy is the orbital diameter at depth y below the surface.
[0036] Vessels can be configured to exploit the difference in motion between Hs and Hy, for example, in the following way. A vessel body is positioned at or near the surface, and a submerged swimmer or glider component is positioned at depth y, and connected to the vessel body by one or more tethers. As waves lift and lower the float portion, wings or fins on the submerged portion passively rotate so as to convert the relative motion of the surrounding water into forward thrust. The azimuth of the thrust vector can be directed completely independently of the direction of the waves by a rudder at the back of the glider. The vessel has multiple wings each with a short chord dimension. This minimizes lost motion between the up stroke and the down stroke and enables successful conversion of even very small waves into forward thrust.
[0037] FIG. 1B is a side view of a wave-powered vehicle that illustrates this principle. The vehicle comprises a float or vessel body 10 resting on the water surface, and a swimmer 20 hanging below, suspended by one or more tethers 30. The float 10 comprises a displacement hull 11 and a fixed keel fin 12. The swimmer comprises a rudder 21 for steering and wings or fins 22 connected to a central beam of the rack 23 so as to permit rotation of the wings around a transverse axis within a constrained range, and provide propulsion.
[0038] In still water (shown in the leftmost panel), the submerged swimmer 20 hangs level by way of the tether 30 directly below the float 10. As a wave lifts the float 10 (middle panel), an upwards force is generated on the tether 30, pulling the swimmer 20 upwards through the water. This causers the wings 22 of the swimmer to rotate about a transverse axis were the wings are connected to the rack 23, and assume a downwards sloping position. As the water is forced downward through the swimmer, the downwards sloping wings generate forward thrust, and the swimmer pulls the float forward. After the wave crests (rightmost panel), the float descends into a trough. The swimmer also sinks, since it is heavier than water, keeping tension on the tether. The wings rotate about the transverse axis the other way, assuming an upwards sloping position. As the water is forced upwards through the swimmer, the upwards sloping wings generate forward thrust, and the swimmer again pulls the float forwards.
[0039] Thus, the swimmer generates thrust when both ascending and descending, resulting in forward motion of the entire craft.
Autonomous Navigation
[0040] A wave-powered vessel may be configured to navigate across a body of water autonomously (without human attendance), and to perform its own power management.
[0041] Self-directed navigation is possible when the vessel is equipped with a means of determining the geographical location of the vessel, a means for determining direction, a means for steering the vessel, and a means for operating the steering so that the vessel travels or stays at a target location. The steering means is typically a rudder that turns sideways against the water so as to cause the vessel to spin towards a new heading. Alternatively or in addition, it may be a mechanical arrangement that presses upwards and downwards on opposite sides of the vessel in the manner of an aileron, thereby causing the vessel to roll sideways and attain a new heading. Where the vessel comprises a float and a swimmer connected by a single tether, it is usual to put the steering means on the swimmer providing the locomotive power. In configurations having two or more tethers, a rudder may be placed on the float, the swimmer, or on the float and the swimmer together.
[0042] Electronics to sense the geographical location of a vessel can triangulate off a series of reference points. Particularly effective is the global positioning system (GPS), or a similar network of positional transmitting sources. The vessel will also usually have an electronic compass or gyroscope to determine the vessel heading. Positional data about the geographical location and the vessel heading is processed in a decision algorithm or programmed microprocessor, which may then provide navigation instructions. Consequently, the steering means adjusts to head the vessel in accordance with the instructions.
[0043] FIG. 2 shows an example of an algorithm for directing a vessel towards or maintaining it at a target position (a geographical location). Once the target position is inputted, it is compared with the current location of the vessel inputted from a GPS receiver. The processor calculates the proper heading, and compares it with the heading inputted from the compass. The processor then outputs instructions to the rudder servo to adjust the vessel onto the correct heading. For vessels that are capable of regulating transit speed or locomotive force, the processor may also output instructions to adjust the speed (not shown). Measurement and correction by comparison with GPS and compass data is performed iteratively as the journey continues.
[0044] Electrical power is typically needed for the electronics used for self-navigation. This can be supplied by photovoltaic cells located on the deck of the vessel. For low wind resistance, for low visibility, and to reduce the sensitivity to the direction of the sun, it is best if this surface is horizontal. For example, the top deck can be installed with SunPower(TM) E20 panels each containing 96 Maxeon(TM) cells. Under standard conditions (irradiance of 1000 Watts/m<2>, AM 1.5, and cell temperature of 25[deg.] C.) six panels produce a total of 1962 Watts.
Converting Wave Movement to Electrical Power
[0045] This invention advances the field of wave-powered watercraft by providing two sources of locomotive power. One is a highly efficient mechanical conversion of wave motion directly to locomotive thrust, as described earlier in this disclosure. The second is conversion of wave motion to electrical power, which can be stored and used at a later time. Having the two systems on board provides a number of advantages.
[0046] FIG. 3 shows the availability of solar power as a function of the annual cycle, and as a function of time (adapted from M D Ageev, Advanced Robotics 16(1):43-55, 2002). Depending on the size and efficiency of the photovoltaic cells, there may be periods when solar power is inadequate to power the electronics on board. A battery system can be used to buffer and sustain the electronics through diurnal variation, but if the vessel spends long periods in the far north, for example, solar power may be inadequate. On the other hand, using wave motion for locomotive thrust may be insufficiently reliable at or near the equator or in summer months.
[0047] The makers of this invention have discovered that when wave motion is high, enough power can be harvested not only to propel the vessel through the water, but also to provide ample electrical power. In fact, enough electrical power can be harvested from the waves not only to power the electronics, but also to create an energy supply that can later be used for locomotion. An electrical generator can be driven by vertical and/or horizontal movement of the vessel caused by the waves. The vessel is configured so that the vertical undulations of the vessel are mechanically coupled to a means of providing horizontal locomotive power to the vessel (such as a fin or wing rack), and are also mechanically coupled to a generator of electrical power.
[0048] In vessels equipped in this way, other sources of electrical power (like photovoltaic cells for solar power) are entirely optional-the wave motion mechanically provides power to drive the vessel through the water, and also provides electricity to run electronics and microprocessors aboard.
[0049] When electrical power generated from wave motion and/or from solar panels is in excess of immediate needs, it can be stored in an on-board rechargeable battery. The stored electrical power can be used at a later time to power on-board electronics and microprocessors. It can also be used to power an electrically driven propulsion system, such as an electric motor coupled to a propeller or turbine. Thus, on calm days when there is insufficient wave motion to drive the vessel at the desired speed, the battery (optionally in combination with photovoltaic cells) can power the propulsion system. Conversely, the wave generated electrical power can be stored for use during periods that are too dark to rely entirely on solar power-for example, at night-and/or to supplement locomotive thrust.
[0050] FIG. 4 is a block diagram summarizing how the interaction of power sources can occur. Sources of power are indicated on the top line; results at the bottom. Wave motion can provide locomotive thrust by mechanical interconnection, such as in a two-part vessel where a floating portion is tethered to a submarine portion. Wave motion can also power a generator adapted for implementation on a vessel, which generates electricity delivered to a rechargeable battery. Vessel motion through the water (a result of propulsion mechanically generated from the wave action) can power an electrical generator of its own, which also feeds the battery. Solar panels (if present) also provide electrical power to a battery. Although they may be separate, typically the battery for any two or three of these power sources are shared by the sources that are present.
[0051] Electrical power from the battery supplies on-board electronics, such as navigation equipment, a microprocessor that manages power allocation, and sensors or detectors of various kinds. Electrical power can also be tapped at any time it's available to provide vessel proportion: either to supplement thrust obtained from the wave motion mechanically, or to substitute for mechanical thrust at times when wave motion is insufficient. As explained below, the electric motor may be the same apparatus as the electrical generator powered by vessel motion, run in reverse to provide vessel propulsion.
[0052] FIG. 5A, FIG. 5B, FIG. 6A, and FIG. 6B are side views of a vessel that illustrates how wave motion can be converted to electrical power. The vessel has been equipped to harvest wave motion for both locomotive and electrical power. There are two tethers 33a and 33b connecting the vessel body 31 to the swimmer 32, fastened to opposite arms 34a and 34b of a suspension device 37 by way of rotating hinges 35. The arms of the suspension are spring loaded to return to a neutral horizontal configuration in opposite directions along an axis parallel to the vessel's length, pivoting around a central suspension point 36.
[0053] Also shown on the vessel body 31 are a propeller 41 powered by an electric motor 42, a rudder 43, and an assembly 44 for receiving and transmitting data and operating instructions that is mounted on the top deck 45. The configuration can be adapted with more tethers attached to more link arms that fold forwards and/or backwards, and are mounted on the vessel body 31 beside, in front, or behind the suspension device 37 shown here.
[0054] FIG. 5A superimposes three images showing what happens when the vessel body 31 is lifted by a wave. At the starting position, the suspension device 37 is configured in the neutral position with arms 34a and 34b horizontally positioned in opposite directions. As the wave lifts the vessel body 31, it pulls the swimmer 32 upwards. However, the density of water slows the upward movement of the swimmer 32, thereby pulling the arms 34a and 34b of the suspension device 37 downwards. This loads the spring on each arm with potential energy.
[0055] FIG. 5B superimposes three images showing what happens as the vessel approaches the crest of the wave. The upwards motion of the vessel body 31 slows, but the swimmer 32 still travels upwards due to the tension in the arms when they were being pulled downward. As the swimmer 32 continues upwards to a point where the arms 34a and 34b resume the neutral horizontal position, the potential energy in the suspension device 37 is released, and can be captured by a generator means that converts the potential energy in the spring into electrical power.
[0056] FIG. 6A superimposes three images of the configuration of the suspension device 37 as the potential energy is released. In this example, the two tether winches 33a and 33b pivotally mounted 35 to the ends of link-arms 34a and 34b drive a piston: specifically, a linear hydraulic cylinder 38, which in turn creates pressure to drive a hydraulic turbine generator (not shown). For simplicity the hydraulic cylinder 38 is shown here attached to only one of the link arms 34a, although more typically there is another hydraulic cylinder attached to the other link arm 34b. The link arms 34a and 34b could package nicely in the center span structure without protruding above the deck 45 of the vessel body 31. Optionally, the link arms 44a and 44b can be configured to lock in the neutral horizontal position during times where all of the wave energy is needed for thrust, or when electric generation is not necessary.
[0057] FIG. 6B provides a detail of the action of the hydraulic cylinder 38 during a cycle of movement of the link arm 34a from the neutral horizontal position to the vertical tending spring loaded position as the swimmer is pulled upwards by the vessel body 31 as the wave peaks. When the link arms are in the neutral position, the hydraulic cylinder is extended 39a, and is pushed together 39b into a compressed position 39c as the link arm 34a descends towards the vertical. When the link arm 34a returns to the horizontal position as the wave troughs, the hydraulic cylinder returns to the extended position 39a, completing the cycle.
[0058] The arrangement shown in these figures may be adjusted to the user's liking to fit a particular installation. The swing arm system shown in FIG. 5A, FIG. 5B, FIG. 6A, and FIG. 6B may be placed on the swimmer rather than on the float. The link arms are pivotally mounted at the proximal end towards the upper surface of the swimmer, and are spring loaded to assume a horizontal neutral position. The tether is attached to the distal end of the arm, and connects to the float above. Wave motion again stretches the distance between the float and the tether, but in this case the link arms are pulled into an upwards orientation, creating potential energy in the spring that can be converted to electrical power.
[0059] Whether mounted on the float or the swimmer, the electrical power generation system may harvest the up and down motion of the link arms by a suitable arrangement that ultimately results in a mechanical force turning conductive wire or bar within a magnetic field, or turning a magnet through a conductor. Included are mechanical arrangements that result directly in rotatory motion (such as a rotating axle), or a back-and-forth action (such as a liquid or gas filled piston) that can be converted mechanically into rotatory motion.
[0060] The electrical power generation system shown in FIG. 5A, FIG. 5B, FIG. 6A, and FIG. 6B are provided by way of an example of how such a system may be implemented with high conversion efficiency. The example is not meant to limit practice of the claimed invention except where explicitly indicated. Other systems for harnessing electricity from wave power on a moving vessel may be adapted from stationary on-shore technology now deployed or under development.
[0061] Electrical power generating systems may be configured to harness vertical oscillation of the water surface in a wave cycle, or horizontal movement of the wave peaks, or a combination of the two. By way of illustration, a system that harvests electrical power from vertical movement can comprise a tube that floats vertically in the water and tethered to the vessel. The tube's up-and-down bobbing motion is used to pressurize water stored in the tube below the surface. Once the pressure reaches a certain level, the water is released, spinning a turbine and generating electricity. In another illustration, an oscillating water column drives air in and out of a pressure chamber through a Wells turbine. In a third illustration, the power generating system comprises a piston pump secured below the water surface with a float tethered to the piston. Waves cause the float to rise and fall, generating pressurized water, which is then used to drive hydraulic generators.
[0062] To harvest horizontal wave movement, the electrical power generating system may comprise one or more large oscillating flaps positioned to catch waves as they go by. The flap flexes backwards and forwards in response to wave motion, which in turn drives pistons that pump seawater at high pressure through a pipe to a hydroelectric generator. Another implementation comprises a series of semi-submerged cylindrical sections linked by hinged joints. As waves pass along the length of the apparatus, the sections move relative to one another. The wave-induced motion of the sections is resisted by hydraulic cylinders, which pump high pressure water or oil through hydraulic motors via smoothing hydraulic accumulators. The hydraulic motors drive electrical generators to produce electrical power.
Converting Horizontal Movement of the Vessel to Electrical Power
[0063] Another way of converting wave motion to electrical power is a two-step process. The first step is to use the wave motion to create locomotive thrust, thereby causing the vessel to move through the water. The second step is to harvest the movement of the water about the vessel resulting from the locomotion, and convert it to electrical power.
[0064] FIG. 7, FIG. 8A, and FIG. 8B show an example of a vessel that uses wave motion to generate both locomotive thrust and electrical power from vessel motion. In this example, the swimmer or wing-rack is tethered to the buoy or vessel body by a forward and aft tether with a winch for adjusting the length of tether that is deployed. As the buoy moves up and down with the waves, the swimmer rack has wings that translate the vertical movement into transverse locomotive movement. The wing-rack then pulls the vessel body as directed by the rudder under control of the microprocessor.
[0065] The electrical system shown here comprises upward facing solar panels, providing an auxiliary source of electrical power. The power module for generating electricity is shown in detail in FIG. 8B. The module comprises rechargeable batteries, a rotating magnet conductor arrangement that plays the role of both motor and generator, and a third component that plays the role of both propeller and turbine. As shown in FIG. 7, when there is an abundance of wave power, the wings on the swimmer generate thrust or locomotive power to move the vessel forward. As the waves power the vessel through the water, the propeller is turned backwards, applying torque to the motor so as to generate electrical power for storage in the battery. When there is an absence of wind power, or when the wing rack is retracted into the vessel body, the batteries or solar panel powers the motor, which turns the propeller so as to provide locomotive power.
[0066] The power module is shown in FIG. 8A secured to one side of a catamaran type float. This can be varied to secure the power module for example to the other side, to the middle of a float with a central keel, or to the side rails or middle spine of the swimmer. Two or more power modules can be used, secured for example to both sides of a catamaran type float, or to a float and swimmer together in any combination.
[0067] In the example shown, the hull type is a displacement catamaran, which has the advantage of being very efficient below the hull speed, and can be powered up to 3 times faster than the hull speed with minimal wake. It has six 325 watt SunPower panels for almost 2000 watts peak solar power collection. It also has two Tesla-sized lithium ion battery packs housed in cylindrical power modules that are pressure tolerant to 200 m. These packs each have roughly 7000 cells totally 25 kWh of energy. The power modules are 12.75 inches in diameter-the same as a Remus 600 or a BlueFin 12D AUV.
Balancing Between Locomotive Thrust and Electrical Power Generation
[0068] In some implementations of the invention, the various power harvesting systems on a vessel may be configured to be regulated so as to prioritize delivery of power from wave motion to locomotive thrust or electricity generation in the desired proportion.
[0069] The electrical power generating system may be configured to lock out or variably dampen movement of the components that convert the wave motion to rotatory motion, and hence to electricity. For example, the link arm system shown in FIG. 5A, FIG. 5B, FIG. 6A, and FIG. 6B may be designed so that the link arms may be secured by a clamp or other means in the horizontal neutral position. This effectively locks out the power generating system in favor of the wave-powered propulsion system, which may be desirable when the wave motion is not in excess of what is required to propel the vessel at the intended speed, and/or when electrical power is not needed (for example, when the battery is charged to full capacity). In a variation of this system, the damping is variable, so that the proportion of wave motion used for electrical power generation may be precisely adjusted.
[0070] Conversely, the wave-powered propulsion system may be configured to lock out or variably dampen movement of the components that convert the wave motion to thrust. For example, the wings or fins shown in FIG. 1B may be designed so that they may be secured in a neutral position. This effectively locks out the propulsion system in favor of the electrical power generating system, which may be desirable when the wave motion is well in excess of what is required to propel the vessel at the intended speed, and/or when electrical power is needed in greater abundance to power on-board electronics and/or recharge the battery. In a variation of this system, the damping is variable, so that the proportion of wave motion used for locomotive thrust may be precisely adjusted.
[0071] Besides adjusting use of the wave motion between thrust and electricity generation, a variable damping system on the propulsion system may have a further benefit: namely, to regulate speed of the vessel depending on the amount of wave motion currently available, and the desired target location. For example, when it is desired that the vessel stay in position at its current location, the propulsion regular and rudder may be caused assume a direction and speed that exactly compensates for the net effect of underlying current, wind, and horizontal wave force affecting the vessel's position. This effectively secures the vessel at its current GPS location, and saves the vessel from having to travel in circles to maintain its position.
[0072] Thus, either the propulsion system, or the electrical power generating system, or both may be configured with a lock out or variable damping arrangement to adjust the priority between the two systems.
[0073] Where such regulation systems are installed, they may be controlled by an on-board microprocessor programmed to determine the appropriate priority between locomotion and electrical power generation, and then to regulate the damping or lockout devices on each system accordingly. The microprocessor may be programmed to take into account such factors as vertical wave motion, latitude (determined by GPS), temperature, other weather factors, battery level, distance from the intended target location, amount of available solar power, time of day, payload, sensor data, and operating parameters programmed into or transmitted to the microprocessor.
[0000] Alternating Locomotive Thrust from Wave Motion and an Electrical Motor to Buffer Vessel Speed
[0074] Stored electrical power in the battery can be used to power the electric motor and provide propulsion whenever desired. Besides powering the motor during periods when wave motion is quiescent, it can be used on an ongoing basis to buffer the trust powered by the wave motion.
[0075] FIG. 9 is a graph of hypothetical data that illustrates how this might work. Mechanisms that convert wave motion into locomotive power by gradually pressurizing a gas or a liquid may provide fairly uniform thrust. However, other mechanisms result in undulations in thrust that occur once or twice per wave cycle. For example, in a configuration where a wing rack is tethered beneath a float (as in FIG. 1B), the mechanism provides forward thrust while the rack is travelling upwards or downwards in the wave cycle. When the wave is peaking or at its nadir, tension on the tethers is fairly constant, and forward thrust is minimal. Thus, in a single wave cycle (as shown in FIG. 9), forward thrust peaks twice.
[0076] In many uses of a wave-powered vessel, the undulations are of little consequence. However, there are instances in which a constant speed (and thus relatively constant thrust) is desirable: for example, when using sensors that comprise streamers flowing backwards from the vessel. The undulations in thrust obtained by mechanical conversion can be buffered by powering the electrical motor in an undulating pattern of the same frequency but essentially out of phase. In this manner, thrust from mechanical conversion and thrust from the electric motor alternate, so that the combined locomotive thrust is buffered to a more consistent level. The pattern of power to the electric motor may be controlled by an on board microprocessor programmed to detect the wave cycle, predict the undulations in mechanically derived locomotive thrust, and synchronize the electric motor out of phase to compensate.
Watercraft Configured for Self-Deployment
[0077] Another advantage of the hybrid powered vehicles of this invention is that in many instances they may be deployed directly from shore. This saves the trouble and expense of hiring a special vessel and crew to do the deployment in deep water. Instead, the components of the vessel are kept bound together, and the electric motor powers the vessel to deep water for full deployment.
[0078] For example, a wave-powered vessel configured for deployment from shore may comprise a buoyant vessel body, a swimmer configured to retract and be secured against the vessel body, one or more tethers connecting the float to the swimmer, an electrically powered motor configured to propel the vessel through the water, and a battery supplying power to the motor, having sufficient capacity to power the vessel from shore to a location where the swimmer can be deployed. The battery is charged up before launch, and the swimmer is kept secured to the float. The electric motor takes the vessel to deep water, and then the tethers are let out to deploy the swimmer to its operative position below the float-either automatically, or by remote control. After deployment, the battery can be recharged on an ongoing basis using the electrical power generating systems aboard the vessel.
[0079] FIG. 10 provides a further illustration. Some projects with wave powered vessels require the vessels to take a substantially massive payload. If kept aboard the float or the swimmer, the payload could impair vertical movement, and thus reduce efficiency of the vessel for converting wave motion to thrust and electrical power. Typically, the payload is towed in a container or platform referred to as a "tow buoy" behind the float or the swimmer, either on or below the water surface. However, deploying the vessel and the tow buoy separately from shore is difficult.
[0080] The figure shows how the vessel body and the tow buoy may be configured so that the tow buoy may be releasably housed within the vessel body while on shore, and pulled behind the vessel body after the vessel is deployed. The refinements shown include rollers to guide the tow buoy up one or more complementary ramps inside the float. To transport the vessel to the launch site, the tow buoy is positioned securely inside the float, and the tethers connecting the wing racks to the float are retracted so that the wing racks nest securely to the bottom of the float. Following launch, the precharged battery powers the vessel to deep water, whereupon the wing racks are deployed downward, and the tow buoy is deployed out the back of the float so as to be towed by the float without impairing the float's vertical movement due to wave motion.
Use of Wave-Powered Watercraft
[0081] The hybrid wave-powered vessels of this invention can be manufactured, sold, and deployed for any worthwhile purpose desired by the user. For example, the vessels can be used to survey and monitor regions of the ocean or other bodies of water, including the chemistry of water and air, weather, and marine life. The vessels can be used to relay signals from sensors under the water or on other vessels to a data processing center. They can be used to monitor activities on shore, and the behavior of other watercraft. They can also be used to distribute substances into the ocean from the vessel body or from a tow buoy.
[0082] Sensors and related equipment that may be used include one or more of the following in any suitable combination:
Sensors for gas concentrations in air or water
Heat flux sensors
Meteorological sensors: wind speed & direction, air temperature, solar intensity, rain fall, humidity, pressure
Physical oceanography sensors; wave spectrum & direction, current sensors, CTD profiles
Micro-organism counts and classification through water sampling and vision systems
Fish and wildlife tracking by acoustic tag detection, such as those manufactured by Vemco
FAD structures to provide shade and attract marine life
Acoustic sensors for active or passive detection and classification of marine wildlife. For example, hydrophone for listening to whales, or active sonar for fish counts
Chemical sensors to detect the concentration of a substance being released by the vessel
[0092] Equipment installed on a vessel of this invention to facilitate data collection may include a means for obtaining sensor data at variable depths. This can be achieved using a winch system to lower and raise sensors mounted on a heavier-than-water platform. Another option is a tow buoy mounted with sensors, with servo-controlled elevator fins to alter the pitch of the tow body, thereby controlling its depth while being pulled. The vessel may also have data storage systems and a microprocessor programmed to process and interpret data from the sensors, either integrated into the location and navigation processing and control system on the vessel, or as a stand-alone microprocessor system.
[0093] Watercraft of this invention equipped with sensors and/or payloads have a variety of sociological and commercially important uses. Such uses include fertilizing plankton, feeding fish, sequestering carbon from the atmosphere (PCT/US2012/029718), conducting seismic surveys (US 2012/0069702 A1) or prospecting for new sources of minerals or fuel oil.
Glossary
[0094] The terms "vessel", "watercraft", and sea going "vehicle" are used interchangeably in this disclosure and previous disclosures to refer to a nautical craft that can travel across and about any body of water at or near the surface.
[0095] A "wave-powered" vessel is a vessel that derives at least a majority of its power for locomotion from motion of the water in relation to the surface. Optionally, the vessel may also derive power from solar energy and other natural sources, and/or man-made sources such as batteries and liquid fuel powered engines. In this context, a "wave" is any upward and downward motion of the surface of a body of water at a point of reference (such as the center of floatation of a vessel).
[0096] A "vessel body" or "float" is a component of a vessel that travels on or near the surface of the water. It may have its own source of locomotive power and/or rely on being pulled by a submarine component. It is made buoyant by having a density (including enclosed air pockets and upward opening cavities) that is
[0097] A "swimmer", "pod", "submarine component", "sub", "glider" or "wing rack" is a component of a vessel that travels below the surface of the water and below the vessel body, to which it provides locomotive power or propulsion. The swimmer is heavier than water, so as to travel downwards through the water to the extent allowed by the tethers and the vessel body and suspension systems to which the tethers are attached above. It is typically equipped with a plurality of "fins" or "wings" that rotate upwards or downwards around an axle transverse to the direction of travel. This disclosure generally refers to vessels having single swimmers or wing racks. However, vessels may be configured with multiple swimmers, typically joined to the same two or more tethers at different depths, each providing locomotive thrust in response to wave action, and optionally configured for nesting when retracted (PCT/US2012/029696). Thus, all the aspects of this invention deriving wave power from a swimmer includes or can be adapted mutatis mutandis to include two, three, or more than three swimmers or wing racks.
[0098] An "autonomous" vessel is a vessel that is designed and configured to travel across a body of water without needing a human on board or in constant active control at a remote location. It has a self-contained source of locomotive power. Navigation is controlled, either by a combination of sensors, electronics, and microprocessors aboard or at a remote location and in wireless communication with the vessel. The vessel may also be programmed to manage the ratio of locomotive power derived mechanically from wave action, and from an electric motor. It may also be programmed to control dampening of the action of fins on the swimmer.
[0099] A "tow buoy" is a storage container or equipment platform that is towed behind a vessel, attached either the float or the swimmer, and traveling on or below the water surface. The term does not necessarily indicate that the container or platform has a degree of buoyancy.
[0100] A "microprocessor" or "computer processor" on a vessel or control unit of the invention inputs data, processes it, and then provides output such as data interpretation or instructions to direct the activity of another apparatus or component. For vessels or units that have different data sets for processing in different ways, the microprocessor for each algorithm may be separate, but more commonly they are a single microprocessor configured and programmed to process each the different data sets with the corresponding algorithms when it is appropriate
[0101] The wave-powered vessels of this invention may be organized in fleets of two or more that interact with each other and/or with a central control unit. The terms "control unit", "central control unit" and "control center" are used interchangeably to refer to an electronic assembly or combination of devices that receives information about one or more conditions of the water, the weather, or other aspects of the environment at one or more locations, makes decisions about where it is appropriate to distribute fertilizer or another substance from one or more distribution vessels, and sends instructions to the vessels in the fleet accordingly. The control unit may be placed anywhere on shore within range to receive and transmit data and instructions, or it may be aboard one of the vessels in the fleet, optionally integrated with the microcircuitry of that vessel.
[0102] For all purposes in the United States of America, each and every publication and patent document cited herein is incorporated herein by reference as if each such publication or document was specifically and individually indicated to be incorporated herein by reference.
[0103] While the invention has been described with reference to the specific embodiments, changes can be made and equivalents can be substituted to adapt to a particular context or intended use, thereby achieving benefits of the invention without departing from the scope of what is claimed.
Autonomous wave-powered substance distribution vessels
AU2012228956
Wave power
AU2012211463
Autonomous Wave-Powered Substance Distribution Vessels
US2013006445
WAVE POWER
JP2012046178
Wave power
ZA200806769
Wave power
EG25194
WAVE POWER
WO2008109002
Wave-powered device
TW201309548
AR059212
UN VEHICULO ACUATICO DE POTENCIA DE OLA Y METODO PARA UTILIZAR LA POTENCIA DE LAS OLA
Inventor:
RIZZI ENRICO [US]
KIESOW KURT
