1. Field of the Invention
The present invention relates generally to a recovery system for an unmanned underwater vehicle, and in particular to a modular recovery apparatus for dispensing a tow line with a float, where the recovery apparatus is fitted to the unmanned underwater vehicle.
2. Prior Art
Unmanned underwater vehicles have the characteristic of being easier to launch than to recover, especially in high seas. Restrictions from the sea state dictate if the mission is conducted that day. If the determination was made of the possibility of a high sea state at the time of recovery, or the UUV could not be moved to a shielded area away from the high sea state, the UUV wasn't launched. Recovery is made using a small recovery boat, and damage to the UUV is probable in high seas during recovery when the small recovery boat would hit or run over the UUV. Recovery typically employs a securing sled or a loop wire that snags a hook projecting from the UUV, and a robotic arm that secures the UUV onto the deck of the launch ship.
U.S. Pat. No. 6,779,475 to Jan W Crane and Helmut Portmann, both from Panama City Beach, Fla., discloses a launch and recovery system for unmanned underwater vehicles (UUV). The system includes a watercraft with a stern end wall movable between a vertical position and a ramp position that is angled downward toward the water surface. A storage platform mounted on the watercraft and terminating at the stern end wall defines a storage area for UUVs. An arm is pivotally mounted to the watercraft at a position forward of the storage platform. The arm has an outboard end that can be extended to positions aft of the watercraft and on either side thereof. The arm is also retractable such that its outboard end is positionable over the storage platform. A capture mechanism is mounted to the outboard end of the arm and is used to capture a UUV that maneuvers thereto in the water. A homing mechanism is coupled to the arm and is used to transmit a homing signal through the water for use by the UUV in maneuvering towards the capture mechanism.
The invention provides for a modular recovery apparatus for dispensing a tether spool having a tow line with a float, where the tow line can be used to retrieve an unmanned underwater vehicle and other underwater platforms. The modular recovery apparatus can be triggered underwater or on the surface, and being modular in configuration it is suitable to be fitted to a variety of unmanned underwater vehicles (UUVs). The term UUVs herein collectively includes remotely operated vehicles (ROVs), autonomous underwater vehicles (AUVs), and remotely operated towed vehicles (ROTVs).
An aspect of the invention is that the tow line can be coiled or wound. The modular recovery apparatus is sized to be compatible for integration onto UUVs and underwater platforms of all sizes, and can be retrofitted to existing UUVs. Another aspect of the invention is that the modular recovery apparatus can be deployed underwater and deployed on the surface, using a variety of triggering mechanisms in contact with a release controller.
In one variation of the modular recovery apparatus the tether spool is spring loaded, such that when the tether spool is deployed, the spring projects the tether spool with sufficient force to clearly separate it from the UUV. One end of the tow line is typically fastened to a tow point of the UUV, and an opposing end is attachable to the float. When the tether spool is deployed, the tow line unwinds from the tether spool, providing a securable length. The float carries the tow line toward the surface of the sea, where the tow line can be recovered with a grappling hook, boat hook, a loop, and the like. Once the tow line is recovered it can be brought onboard the recovery ship and the UUV can be pulled in for recovery.
Another variation of the invention includes a modular recovery apparatus having a compression spring loaded inside a canister. The modular recovery apparatus is typically mounted in the nose of the UUV. In one variation a trigger to deploy the float is activated with a burn wire, which in turn releases the compression spring or the tether spool pressing down the compression spring, projecting the tether spool, the net effect being that the tether spool is deployed by the spring with sufficient force to clearly separate it from the UUV. Other triggering devices including solenoids, detonating cords, pyrotechnic initiation devices, compressed gas canisters, and other actuators are anticipated. The triggering device is initiated by a release controller.
The burn wire can be actuated by a variety of methods of communication, including electromagnetic radiation—such as radio frequency (RF), infrared, light, lack of light; sound; a pressure pulse; magneto—inductive emissions; after/at a predetermined time; and having the UUV programmed to deploy the tether spool at the end of a mission. A preferred method for activation when the UUV is on the surface is via radio frequency, and acoustically when the UUV is underwater.
The foregoing invention will become readily apparent by referring to the following detailed description and the appended drawings in which:
The invention is a blow-off float vehicle recovery apparatus where the recovery apparatus is modular, and can be fitted to unmanned underwater vehicles (UUVs) making recovery of them much easier and safer. When recovery is desired the modular recovery apparatus dispenses a tether spool having a tow line with a float, where the tow line is typically attached to a tow point on the UUV. The tow point is typically located on the nose of the UUV. Deployment of the tether spool is actuated using a preferred triggering device. Following deployment, a length of tow line wound on the tether spool separates from the float either by the action of waves, the movement of the UUV relative to the float, the relative buoyancy of the float versus the UUV (if UUV is underwater the float will move toward the surface) or a combination thereof. The tow line preferably also floats, making it relatively easy to grasp, for instance using a grappling hook, a boat hook, and other line snagging tools. Once the tow line is recovered the tow line can be brought onboard the recovery ship and the UUV can be pulled in for recovery.
The modular recovery apparatus can be triggered underwater or on the surface, and being modular in configuration it is suitable to be fitted to a variety of unmanned underwater vehicles (UUVs). Illustrated variations of the invention are discussed below.
Referring to
The canister 12 has a substantially cylindrical wall 13 that interiorly defines a bore 14 with a bore diameter 15 (see
The canister 12 contains a compression spring 88 in a substantially hollow piston 86 that can receive the compression spring when it is compressed. The spring is suggested in
As shown in
Returning to
The stop collar 72 also prevents the compression spring and piston 86 from being expelled from the canister when the tether spool is deployed. Following deployment the head 92 of the piston substantially occludes access to the bore 14. The stop collar 72 is affixed in the bore 14 above the head 92 and below the second end wall 106 of the tether spool. In the illustrated embodiment thumbscrews 74 are used to set the exact position. The stop collar 72 has an outside diameter 73 that is smaller than the bore diameter 15 and an inside diameter 75 that is larger than the overall diameter 105 of the first end wall 104 of the tether spool 100, therefore while the tether spool below the second end wall 106 can easily pass, the piston head is stopped.
The modular recovery apparatus 10, as shown in the Figures, has an actuator framework 52 that includes structural elements connected to the canister 12 and the mounting frame 26 therein forming an integrated unified modular device that can be fitted to UUVs of various missions.
The latch 46 which keeps the tether spool locked in place against the piston holding the compression spring is shown in
The illustrated triggering device is a burn wire 130 in electrical connection with a release controller, such as a radio frequency (RF) release controller for surface activation and/or an acoustic (sound) release controller for underwater activation, both of which can generate an electrical current. The burn wire 130 has an electrically frangible link 132 attached to a first strain relief element 134 with a first lead and a second strain relief element 136 with a second lead. An electrical current causes the electrically frangible link to break therein enabling the lever 50, no longer restrained by its connection to the burn wire 130 and driven by the force of the compression spring 88 against the latch end 46, to rotate to the unlatched position. In one variation, as shown in
In the illustrated variation the UUV nose 144 has a notch 150 in the wall 146 of the opening 148. There is also a notch 40 in the wall of the canister, and a notch 126 in the second end wall 106. The tow line 120 feeds through these notches onto the tether spool 100. In this illustrated variation the burn wire 130 is in electrical connection with a radio frequency (RF) controller 154 for surface activation and an acoustic (sound) controller 152 for underwater activation, where both controllers can generate an electrical current.
As shown in
The canister 12 is substantially cylindrical and has a bore 14 with a bore diameter 15, a contoured open end 16, and an opposing end 18. The opposing end 18 has an end cap 20 with drain holes 22. There is an undercut portion 78 that will fit in the bore 14, and an extended portion 80 that overlaps the end 18. An actuator port 24 is located near the contoured open end 16.
The canister support ring 38, having an inside diameter 42 that is greater than outside diameter 17 of the canister, is fastened to both the canister 12 and a bottom side of the spanning plate 32.
The illustrated apparatus has a hollow piston 86 with a head 92 with a head diameter 87 that is less than the bore diameter 15, where the head 92 has an axial ring 94 that can center an end of the connecting rod 114 of the tether spool 100. The compression spring 88 normally is loaded in the hollow piston 86 in the compressed state. The compressed spring provides the energy to thrust the tether spool out of the canister. In the illustrated variation the piston 86 has several holes 90 in the piston head 92 to allow passage of water.
The tether spool 100 includes a circular first end wall 104 with a beveled perimeter and a bearing 118, a connecting rod 114 attached to first end wall 104 with hardware 116, tow line 120 spooled/wound into a coil 124 on a float 102 having an axial core 108 centered on the connecting rod 114. The float 102 has a winding surface 110 through which projects the connecting rod 114. The float 102 is composed of a material that floats. The tether spool 100 has an opposing second end wall 106. The tether spool 100 is centrally seated in the bore 14 of the canister 12, proximate to the head 92 of the hollow piston 86. The first end wall has an overall diameter 105 that is less than the head diameter 87 of the piston. The second end wall 106 functions as a cover for the apparatus and a pressure point (from the compressed spring) on the latch 46. The second end wall/cover 106 has a cover diameter 107 that is slightly smaller than the bore diameter 15, and therefore substantially occludes the bore.
A stop collar 72 is affixed in the bore of the canister above the head 90 of the piston 86 and below the second end wall of the tether spool. Thumbscrews are used to set the exact position. The stop collar 72 has an outside diameter 73 that is smaller than the bore diameter 15 and an inside diameter 75 that is larger than the overall diameter 107 of the first end wall 104 of the tether spool 100. The outside diameter 107 of the second end wall/cover 106 is greater than the inside diameter 75 of stop collar 72, therefore the second end wall/cover 106 cannot move past the stop collar, however the tether spool below the first end wall 104 can easily pass. The piston head is too wide and it will be stopped.
The illustrated actuator assembly 44 includes a lever 50 with a latch end 46 that latches the tether spool, a pivot point 66, and an intersecting end 48. The intersecting end 48 has an aperture 49 that intersects with the triggering device, which is a burn wire 130 having a frangible link 132, a first strain relief element 134, and a second strain relief element 136. The lever is supported by the lever support assembly 62. The lever support assembly 62 includes a pin (not shown), a cradle 64, and a pivot receptacle 68 for the pin. The intersecting end 48 is substantially U-shaped, which in addition to making the lever stronger, also provides a defined area for the second strain relief element 136.
The burn wire 130 is electrically connected to a release controller 128, where the release controller produces an electrical current when actuated by radio waves, light waves, sound waves (acoustic signals), or magneto—inductive emissions, or when it is automatically activated at a predetermined time, after a predetermined sequence of events, or at the end of a mission.
The mounting frame 26 is preferably composed of an engineering plastic selected from the group consisting of polyoxymethylene polymer, polyoxymethylene copolymers, nylon, polycarbonate, polyetheretherketone, polyvinyl chloride, acrylonitrile butylene stryrene, polyphenylene sulfide, chlorinated polyvinyl chloride, polytetrafluoroethylene, ultra high molecular weight polyethylene, tetrafluoroethylene, ethylene tetrafluoroethylene, acrylic polymers, and methacrylic polymers.
The most preferred engineering plastic is polyoxymethylene polymer, and specifically Delrin™ made by Dupont. The canister 12 and elements of the actuating framework including the shelf plate 54 and the pair of short plates 58, 58′ can also be primarily composed of a similar engineering plastic. Delrin has a relatively low coefficient of friction and is resistant to weathering.
The tow line is preferably composed of a material or combination of materials that floats. Examples include polyethylene and polypropylene. Nylon has a specific gravity that is comparable to seawater. Polyesters, polyamides, polyimides and aramides have a higher specific gravity, and would not float. Lines having a core of nylon, acrylic polymers and ethylene acrylic copolymer covered with an olefinic polymer, like polyethylene, will float.
The engineering plastic can be molded and then machined to have the final construction used in the apparatus.
It is to be understood that the foregoing description and specific embodiments are merely illustrative of the best mode of the invention and the principles thereof, and that various modifications and additions may be made to the invention by those skilled in the art, without departing from the spirit and scope of this invention, which is therefore understood to be limited only by the scope of the appended claims.
The invention described herein may be manufactured and used by or for the Government of the United States of America for Governmental purposes without the payment of any royalties thereon or therefore.
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