DIFFERENTIAL BUOYANCY STEERING

Abstract

Provided is a differential buoyancy steering system for an underwater glider. The inventive system utilizes multiple buoyancy engines to intentionally shift the buoyancy of the glider, thus moving the center of gravity. The shifting of the center of gravity and center of buoyancy causes the glider to roll and/or pitch, which can be used to control the steering of the glider as it travels through a column of water. A control system can independently adjust one or more buoyance engine bladders/plungers to independently control pitch and or roll. Additionally, one or more external turbines on the body of the glider can recharge the power system while the gilder is underway. The inventive method of glider control reduces complexity in the control system, reduces the number of moving parts, and extends times between battery recharge, thus improving reliability and lowering cost.

Claims

1. An underwater glider comprising: a glide body comprising a pair of hydrofoils configured to cause said glider to glide forward while ascending and descending through water; an internal frame; a glider control system; a power source; a port buoyance engine comprising a bladder/plunger; a starboard buoyancy engine comprising a bladder/plunger; wherein said glider control system inflates/extends said port and starboard buoyance engines individually to adjust pitch and roll of said glider as it ascends and descends through water.

2. The underwater glider of claim 1, wherein said glider control system extends/inflates said port buoyance engine more than said starboard buoyancy engine, causing said glider to roll right.

3. The underwater glider of claim 1, wherein said glider control system extends/inflates said starboard buoyance engine more than said port buoyancy engine, causing said glider to roll left.

4. The underwater glider of claim 1, wherein said glider control system extends/inflates said starboard buoyance engine and said port buoyancy engine equally, causing said glider to glide level.

5. The underwater glider of claim 1, wherein said glider control system extends/inflates said starboard buoyance engine and said port buoyancy engine causing a fore center of gravity, an upward pitch, and forward/upward motion.

6. The underwater glider of claim 1, wherein said glider control system extends/inflates said starboard buoyance engine and said port buoyancy engine causing an aft center of gravity, a downward pitch, and forward/downward motion.

7. The underwater glider of claim 1, wherein said glider control system extends/inflates said starboard buoyance engine and said port buoyancy engine causing a neutral center of gravity and no pitch.

8. The underwater glider of claim 1, wherein said glider control system extends/inflates said starboard buoyance engine and said port buoyancy engine independently to simultaneously adjust pitch and/or roll. The underwater glider of claim 1, wherein said starboard buoyance engine and said port buoyancy engine are syringe buoyance engines comprising a plunger that can be extended.

10. The underwater glider of claim 1, wherein said starboard buoyance engine and said port buoyancy engine comprise a bladder that can be inflated and deflated.

11. The underwater glider of claim 1, further comprising one or more ballasts that can be moved to adjust pitch and/or roll.

12. The underwater glider of claim 1, further comprising one or more external turbines that harvest energy from water passing over said glider as said glider rises and falls in a water column.

13. The underwater glider of claim 12, wherein said one or more external turbines enable recharging of one or more batteries while underway.

14. The underwater glider of claim 13, wherein said glider's glide path can be adjusted to maximize recharging of said one or more batteries while underway.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The detailed description of the drawings particularly refers to the accompanying figures in which:

[0010] FIG. 1A shows an exterior perspective view of an underwater glider.

[0011] FIG. 1B shows a perspective view of an underwater glider.

[0012] FIG. 1C shows a perspective view of the internal components of an underwater glider.

[0013] FIG. 2A shows an overhead view of an underwater glider configured for a right turn.

[0014] FIG. 2B shows a frontal view of an underwater glider configured for a right turn.

[0015] FIG. 3A shows an overhead view of an underwater glider configured for a left turn.

[0016] FIG. 3B shows a frontal view of an underwater glider configured for a left turn.

[0017] FIG. 4A shows an overhead view of an underwater glider configured for a level glide.

[0018] FIG. 4B shows a head on view of an underwater glider configured for a level glide.

[0019] FIG. 5A shows an overhead view of an underwater glider with port and starboard buoyance engines positioned aft for increased pitch.

[0020] FIG. 5B shows an overhead view of an underwater glider with port and starboard buoyance engines positioned fore for decreased pitch.

[0021] FIG. 6A shows an overhead perspective view of an underwater glider with turbines.

[0022] FIG. 6B shows a perspective view of an underwater glider with turbines.

DETAILED DESCRIPTION OF THE DRAWINGS

[0023] The embodiments of the invention described herein are not intended to be exhaustive or to limit the invention to precise forms disclosed. Rather, the embodiments selected for description have been chosen to enable one skilled in the art to practice the invention.

[0024] In an illustrative embodiment, provided is an underwater glider comprising: a glide body comprising a pair of hydrofoils configured to cause the glider to glide forward while ascending and descending through water; an internal frame; a glider control system; a power source; a port buoyance engine comprising a bladder/plunger; a starboard buoyancy engine comprising a bladder/plunger; wherein the glider control system inflates/extends the port and starboard buoyance engines individually to adjust pitch and roll of the glider as it ascends and descends through water.

[0025] In an illustrative embodiment, the glider control system extends/inflates the port buoyance engine more than the starboard buoyancy engine, causing the glider to roll right. In an illustrative embodiment, the glider control system extends/inflates the starboard buoyance engine more than the port buoyancy engine, causing the glider to roll left. In an illustrative embodiment, the glider control system extends/inflates the starboard buoyance engine and the port buoyancy engine equally, causing the glider to glide level. In an illustrative embodiment, the glider control system extends/inflates the starboard buoyance engine and the port buoyancy engine causing a fore center of gravity, an upward pitch, and forward/upward motion. In an illustrative embodiment, the glider control system extends/inflates the starboard buoyance engine and the port buoyancy engine causing an aft center of gravity, a downward pitch, and forward/downward motion. In an illustrative embodiment, the glider control system extends/inflates the starboard buoyance engine and the port buoyancy engine causing a neutral center of gravity and no pitch. In an illustrative embodiment, the glider control system extends/inflates the starboard buoyance engine and the port buoyancy engine independently to simultaneously adjust pitch and/or roll. In an illustrative embodiment, the starboard buoyance engine and the port buoyancy engine are syringe buoyance engines comprising a plunger that can be extended. In an illustrative embodiment, the starboard buoyance engine and the port buoyancy engine comprise a bladder that can be inflated and deflated. In an illustrative embodiment, one or more ballasts can be moved to adjust pitch and/or roll. In an illustrative embodiment, one or more external turbines that harvest energy from water passing over the glider as the glider rises and falls in a water column. In an illustrative embodiment, one or more external turbines enable recharging of one or more batteries while underway. In an illustrative embodiment, the glider's glide path can be adjusted to maximize recharging of the one or more batteries while underway.

[0026] FIG. 1A shows an exterior perspective view of an underwater glider 101. In an illustrative embodiment, the underwater glider 101 is an autonomous underwater vehicle (AUV) that utilizes variable-buoyancy propulsion (discussed in greater detail below) instead of conventional propellers or thrusters. Conventional buoyancy type underwater glider steering systems that are known and in use cause a shift of the Center of Gravity (CG) within the glider, which is accomplished by movement of internal mass, thus moving the CG. The misalignment of the CG and center of buoyancy causes the glider to roll or pitch. With dual buoyancy engines the inventive glider 101 can independently adjust buoyancy in each engine 105, 106. A difference in buoyancy between engines 105, 106, will shift the center of buoyancy, causing misalignment with the CG, and thus roll/pitch the glider.

[0027] FIG. 1B shows a perspective view of an underwater glider 101. In an illustrative embodiment, the glider 101 comprises a glide body 110 comprising a pair of hydrofoils 111 configured to cause the glider 101 to glide forward while ascending and descending through water; an internal frame 112, a glider control system 103, a port buoyance engine 105 comprising a bladder/plunger 109, and a starboard buoyancy engine 106 comprising a bladder/plunger 109. The glider 101 utilizes variable buoyancy in a manner similar to a profiling float but additionally includes hydrofoils (underwater wings) that cause the AUV to glide forward while ascending and descending through the water. In an illustrative embodiment, the glider 101 utilizes syringe buoyancy engines 105, 106 with a bladder or plunger 109 (discussed below) that can be inflated or extended. In an illustrative embodiment, the glider control system 103 inflates/extends said port and starboard buoyance engines 105, 106 individually to adjust pitch and roll of the glider 101 as it ascends and descends through water. As the bladder/plungers 109 are inflated/extended, the buoyancy of the glider 101 increases, causing it to rise. As the glider rises, the hydrofoils 111 cause forward propulsion. Once a certain depth is reached, the engines 105, 106 are retracted/deflated, which decreases the buoyancy and causes the glider 101 to sink and continue its forward motion. The cycle is then repeated as desired. In an illustrative embodiment, the underwater glider 101 can be configured in any desired shape. Shown in FIG. 1A is an underwater glider 101 with a blended wing type glide body. In an illustrative embodiment, the glider 101 can be configured to store and transport cargo 102 attached to the exterior of the glider 101.

[0028] FIG. 1C shows a perspective view of the internal components of an underwater glider 101. In an illustrative embodiment, the glider 101 comprises a glider control system 103; a power source 104; a port and a starboard buoyance engine 105, 106 for pitch/roll control, and one or more optional movable ballasts 107. In an illustrative embodiment, the port and starboard buoyance engines 105, 106 comprise a bladder or plunger 109. In an illustrative embodiment, the bladder or plunger 109 can be controlled by a motor, an engine, or a pump. In an illustrative embodiment, the port and starboard buoyance engines 105, 106 are configured in the same position/volume to prevent roll of the glider 101. As the bladder/plunger 109 expand and contract, the overall buoyancy of the glider 101 is increased or decreased. As can be appreciated, expanding will increase buoyancy and contracting will decrease buoyancy. In an illustrative embodiment, a piston type buoyancy bladder comprising a plunger is utilized. In an illustrative embodiment, other types of buoyancy engines, such as balloon/diaphragm types are utilized. In an illustrative embodiment, the port and starboard buoyance engines 105, 106 are controlled by the gilder control system 103 to adjust the pitch and roll of the glider 101. In an illustrative embodiment, the optional movable ballast 107 is controlled by the gilder control system 103 to cause fore and aft movement of the ballast 107, which can also be used to adjust the pitch of the glider 101.

[0029] FIGS. 2A-B show views of an underwater glider 101 configured for a right turn, FIGS. 3A-B show views of an underwater glider 101 configured for a left turn, and FIGS. 4A-B shows views of an underwater glider 101 configured for a level glide. To control roll, the port and starboard buoyance engines 105, 106 are extended/inflated in different positions. In FIG. 2A, the port buoyance engine 105 is extended/inflated more than the starboard buoyancy engine 106, causing the glider 101 to roll right. As can be appreciated, rolling right combined with upward or downward movement will cause the glider 101 to turn right. In FIG. 3A, the starboard buoyance engine 106 is extended/inflated more than the port buoyancy engine 105, causing the glider 101 to roll left. As can be appreciated, rolling left combined with upward or downward movement will cause the glider 101 to turn left. In FIG. 4A, the port buoyance engine 105 is extended/inflated equivalently to the starboard buoyancy engine 106, creating zero roll angle and causing the glider 101 to remain level. In an illustrative embodiment, the port and starboard buoyance engines 105, 106 can be controlled by the glider control system 103.

[0030] In addition to roll, the port and starboard buoyance engines 105, 106 can control the pitch of the glider 101. As shown in FIG. 4A, the port and starboard buoyance engines 105, 106 are extended/inflated equivalently, thereby creating a neutral CG and no pitch. FIG. 5A shows a view of an underwater glider 101 with the port and starboard buoyance engines 105, 106 positioned aft for increased pitch, and FIG. 5B shows a view of an underwater glider 101 with the port and starboard buoyance engines 105, 106 positioned fore for decreased pitch. When the port and starboard buoyance engines 105, 106 are extended/inflated, the CG is altered such that the glider 101 will pitch up causing forward/upward motion. When the port and starboard buoyance engines 105, 106 are retracted/deflated, the CG is altered such that the glider 101 will pitch down causing forward/downward motion.

[0031] In an illustrative embodiment, the port and starboard buoyance engines 105, 106 can be independently adjusted by the glider control system 103 to adjust pitch and roll simultaneously as desired. As a non-limiting example, the port and starboard buoyance engines 105, 106 can be inflated/deflated equally or independently to adjust pitch and/or roll. In an illustrative embodiment, the CG of one or more movable ballasts 107 can also be adjusted to independently adjust pitch and/or roll. In an illustrative embodiment, a combination of the port and starboard buoyance engines 105, 106 and one or more movable ballasts 107 can be adjusted to change the pitch and/or roll of the glider 101.

[0032] In an illustrative embodiment, the inventive differential buoyancy steering system can use more than two buoyancy engines (i.e., 4, 6, 10, etc.). In an illustrative embodiment, a power source can comprise one or more batteries 104. In an illustrative embodiment, the one or more batteries 104 can be positioned in various places within the glider 101. In an illustrative embodiment, one or more batteries 104 can be positioned in the hydrofoils 111. In an illustrative embodiment, the inventive differential buoyancy steering system uses a feed forward type of control. In an illustrative embodiment, the inventive differential buoyancy steering system uses feedback control system that allows for improved differential buoyancy steering.

[0033] FIGS. 6A-B show views of an underwater glider 101 with turbines 601. In an illustrative embodiment, the underwater glider 101 comprises one or more turbines 601 to generate electricity. The turbines 601 harvest energy from water passing over the glider 101 as the glider 101 rises and falls in a water column and converts it into electrical energy. A battery charging circuit within the gilder control system 103 (shown in FIGS. 5A-B) converts the energy captured by the turbines and utilizes it for recharging the one or more batteries 104 (shown in FIG. 5B).

[0034] As can be appreciated, once the buoyance engines 105, 106 are configured appropriately for ascent or decent, the glider 101 is not using an internal power source for motion. As the glider 101 rises and falls, it is being acted upon by external forces (i.e., water currents passing over the body of the glider 101). The water currents cause turbine blades 602 within the turbine 601 to rotate and to capture energy from the water currents. In an illustrative embodiment, a battery charging circuit 103 converts the energy captured by the turbines 601 and utilizes it for recharging the one or more batteries 104 while underway.

[0035] The turbines 601 can extend the range of the glider 101. As can be appreciated, the duration of the glide phase has an effect on the ability of energy available for recharging the system. In some embodiments, slow forward movement and a short duration glide permits only a small amount of electrical charge to be captured for recharging. In some embodiments, a long glide phase increases the amount of energy captured by the turbines. In an illustrative embodiment, a longer glide duration may produce sufficient energy to fully recharge the system. In an illustrative embodiment, the glide path can be adjusted in such a manner as to produce a positive electrical gain for the glider 101, meaning the glider 101 could remain underway indefinitely. In such embodiments, the glider 101 charges its batteries while underway, thereby eliminating the need for fixed location charging. As such, shore based recharging utilizing fossil fuels may be eliminated, providing significant cost and resource savings.

[0036] Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the spirit and scope of the invention as described and defined in the following claims.