Abstract:
An unmanned system performs inspection, identification and/or neutralization of underwater objects. An unmanned vehicle that operates at a water&#39;s surface stows underwater crawling and/or swimming vehicles that can operate underneath a water&#39;s surface. A winch associated with each robotic vehicle is mounted on the unmanned vehicle. An electro-mechanical tether electrically and mechanically couples a corresponding robotic vehicle to the unmanned vehicle, and is mechanically coupled to a corresponding winch for control of the paying out and reeling in thereof.

Description:
ORIGIN OF THE INVENTION 
   The invention described herein was made in the performance of official duties by an employee of the Department of the Navy and may be manufactured, used, licensed by or for the Government for any governmental purpose without payment of any royalties thereon. 

   FIELD OF THE INVENTION 
   The invention relates generally to the inspection, identification and neutralization of underwater objects, and more particularly to an unmanned system for underwater object inspection, identification and/or neutralization. 
   BACKGROUND OF THE INVENTION 
   Current Navy methods for reacquisition, identification and neutralization (RIN) of mines in very shallow water (i.e., 10-40 feet) and surf zone (i.e., 0-10 feet) utilize divers and/or marine mammals (e.g., dolphins and sea lions) to relocate contacts found by mine search sonars and to deploy countercharges to destroy the mines. These approaches risk personnel who must enter the minefields and endanger themselves by being visible on the surface from enemy shores, and by having to work around mines while in moving currents and waves. 
   Recently, unmanned vehicles have been used to search for and neutralize mines. Unmanned underwater vehicles (UUVs) that swim in the water column are currently in the fleet for performing search, classify and mapping (SCM) missions. These swimming vehicles are ideal for carrying side-scan sonar to perform wide area reconnaissance of minefields. They can efficiently scan large areas and map mine-like sonar contacts. Under ideal conditions, UUVs can identify sonar contacts using cameras or specialized imaging sonars. However, it is difficult for UUVs to place countercharges on the mines or to identify them under poor optical or acoustic conditions. In addition, UUVs generally rely on acoustic navigation aids which must be pre-positioned within the minefield before the vehicles can function. The UUVs must be delivered near to or into the minefields by personnel in boats thereby endangering the delivery personnel. 
   Bottom-crawling robots (i.e., “crawlers”) provide a stable base for identifying and prosecuting mines that were contacted by a UUV and are thus ideal for performing the RIN mission. A crawling robot can approach an object and apply sensors (e.g., image the object) at contact range. The natural stability of the crawler and the fact that it moves along the bottom offers the opportunity to exploit new target features for identification of mine-like contacts. The crawler can neutralize mines easily by dropping a countercharge or by serving as a sacrificial, mobile countercharge. 
   However, crawlers cannot transit long distances. Further, they can easily become stuck while transiting over rough bottoms. Still further, because of their limited energy, personal in boats must deliver the crawlers into or close to the minefields. For these reasons, crawlers have been considered only for limited use for performing mine neutralization missions. 
   Vehicles that can both swim and crawl have limited payload, speed, and range capabilities. The limitations derive mostly from the physics of buoyancy since it is necessary for the vehicle to release either ballast or buoyancy material to enable it to swim or to be heavy enough to navigate along the bottom and stay in place to neutralize a mine. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is an object of the present invention to provide an unmanned system that can efficiently and effectively perform one or more of inspection, identification and neutralization of underwater objects. 
   Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings. 
   In accordance with the present invention, an unmanned system performs inspection, identification and/or neutralization of underwater objects. At least one remotely-operated robotic vehicle is provided that can operate underneath a water&#39;s surface. Each robotic vehicle has a slave controller, electrical propulsion system, underwater sensors, and is equipped for explosive charge deployment. An unmanned vehicle that operates at a water&#39;s surface includes a mother controller, self-propulsion, navigation, wireless communication, electrical energy generation systems as well as the ability to stow each robotic vehicle. A winch associated with each robotic vehicle is mounted on the unmanned vehicle. An electro-mechanical tether electrically and mechanically couples a corresponding robotic vehicle to the unmanned vehicle. Each tether is also mechanically coupled to a corresponding winch for control of the paying out and reeling in thereof. Each tether electrically couples the unmanned vehicle&#39;s to the robotic vehicle for electrical energy and control signal transfer thereto. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, features and advantages of the present invention will become apparent upon reference to the following description of the preferred embodiments and to the drawings, wherein corresponding reference characters indicate corresponding parts throughout the several views of the drawings and wherein: 
       FIG. 1  is a block diagram of the systems maintained onboard an unmanned surface vehicle in accordance with the present invention; 
       FIG. 2  is a block diagram of the systems maintained in each of the surface vehicle&#39;s hold regions; 
       FIG. 3  is a block diagram of the systems maintained onboard an unmanned bottom crawling vehicle transported and deployed by the unmanned surface vehicle in accordance with the present invention; 
       FIG. 4  is a block diagram of the systems maintained onboard an unmanned swimming vehicle transported and deployed by the unmanned surface vehicle in accordance with the present invention; and 
       FIG. 5  is a plan view of multiple pontoon boat embodiment of the unmanned surface vehicle. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention is an unmanned system that can be used to inspect, identify and/or neutralize a variety of underwater objects (e.g., underwater mines, unexploded ordnance, pipelines, or other underwater objects). In general, the unmanned system can deploy from a remote location and travel relatively long distances on the water, deploy one or more robotic vehicles therefrom to perform underwater operations as controlled from the water&#39;s surface, and retrieve the robotic vehicle(s) for return travel to a remote location. More specifically, the present invention includes an unmanned surface vehicle or boat that can stow one or (typically) more robotic vehicles while in transit to an area of interest, deploy and control the robotic vehicles using systems maintained on the boat, and ultimately retrieve and stow the robotic vehicles. Accordingly,  FIGS. 1-3  depict block diagrams of the boat&#39;s capabilities ( FIG. 1 ) and the capabilities of two different types of robotic vehicles ( FIGS. 2 and 3 ). By way of example, the present invention will be described for its use in the inspection, identification, and neutralization of underwater mines. 
   Referring first to  FIG. 1 , a boat  10  and its various functional systems are illustrated in block diagram form. Boat  10  can be realized by a variety of different designs, one of which will be described later herein. At the heart of the functional capability of boat  10  is its control, piloting and navigation computer  12  that supports and/or controls the various systems coupled thereto. Since boat  10  must be capable of relatively long-distance navigated travel on the water, a GPS antenna and receiver system  14  provide GPS location data to computer  12 . The GPS location data could be used by computer  12  to automatically implement a pre-determined navigation plan. Additionally or alternatively, the GPS location data can be provided to a communications transceiver  16  for wireless transmission over the airwaves by a communications antenna  18 . In this way, the GPS location data could be monitored at a remote location or used by an operator at a remote location to pilot boat  10  from the remote location. That is, the operator could wirelessly transmit navigation control signals to boat  10  (i.e., via antenna  18  and transceiver  16 ) based on the GPS location data. 
   Boat  10  must be able to propel itself to and from locations of interest, and further provide operational power to the one or more robotic vehicles that it supports. Accordingly, boat  10  must be capable of generating its own mechanical and electrical power as well as operational power for its robotic vehicles. One way of achieving this is for boat  10  to have a conventional air-breathing engine/propulsion system  20  onboard, a fuel tank  22  supplying fuel to engine  20 , and a generator  24  coupled to engine/propulsion system  20 . In this way, engine/propulsion system  20  provides mechanical power for propulsion of boat  10  and for generator  24  which converts mechanical power to electrical power. A battery  26  could be coupled to generator  24  to store excess electrical power and/or to provide regulated power for those systems onboard boat  10 . 
   In addition to engine/propulsion system  20 , boat  10  will be equipped with steering mechanisms  30  controlled by computer  12 . Such mechanisms  30  would typically include both macro steering mechanisms  30 A (e.g., rudders) and micro steering mechanisms  30 B (e.g., side thrusters). Macro steering control is implemented when boat  10  is traveling to and from an area of interest. Micro steering control is implemented when boat  10  is “on station” at an area of interest with its robotic vehicle(s) deployed in the water as will be explained further below. 
   As previously mentioned, boat  10  is equipped to stow one or more robotic vehicles during travel to and from an area of interest. The robotic vehicles can be “bottom crawling” vehicles capable of traversing the bottom of a body of water, and/or “swimming vehicles” capable of controlled movement under the water&#39;s surface. Accordingly, boat  10  has hold region(s)  40 , each of which can stow, deploy and retrieve one robotic vehicle. Control signals for hold regions  40  are provided by computer  12  while electrical power is supplied by one or both of generator  24  and battery  26 . Since each hold region  40  will be similarly equipped, only one such hold region  40  will be described with the aid of  FIG. 2 . 
   Referring now to  FIG. 2 , an interface  42  in hold region  40  receives both control signals and electrical power as illustrated in  FIG. 1 . An electro-mechanical tether  44  is coupled on one end thereof to interface  42  and is coiled about a winch  46 . The other end of tether  44  is coupled to a robotic vehicle  48 . Upon reaching an area of interest, boat  10  can deploy robotic vehicle  48  by paying out tether  44  using winch  46 , power and control robotic vehicle  48  during its mission, and then reel in tether  44  using winch  46 . 
   Robotic vehicle  48  can be either a bottom crawling or swimming vehicle. The drive system associated with a bottom crawling vehicle will be different from that of a swimming vehicle. Accordingly, the systems maintained onboard a (robotic) bottom crawling vehicle and swimming vehicle will be explained with the aid of  FIGS. 3 and 4 , respectively. 
   In  FIG. 3 , a bottom crawling vehicle  50  has an interface  52  to which tether  44  is coupled. Electrical power provided via tether  44  is directed to power converters/regulators  54  which, in turn, provides the necessary electrical power for the systems onboard vehicle  50 . Operational and navigation control signals can be provided by computer  12  (onboard boat  10 ) and directed to a control computer  56 . In this scenario, computer  12  functions as a “mother controller” to computer  56  while computer  56  functions as a “slave controller” to computer  12 . Optionally, onboard navigation systems  58  (e.g., long baseline navigation, local navigation sensors such as gyros, inclinometers, odometers, compass, etc.) can be provided and coupled to computer  56  to supplement the navigation control received from boat  10 . 
   Computer  56  provides local control signal distribution to an electrically-driven traction drive system  60 , an explosive charge control system  62 , and a sensing system  64 . For controlled movement on the water&#39;s bottom, traction drive system  60  would typically include individually-controllable left and right traction drives  60 A and  60 B. A variety of such systems are known in the art of ground traversing vehicles. Sensing system  64  would typically include one or more sonar sensors  64 A and a video camera  64 B. Outputs from sensor system  64  are provided to computer  56  for use thereby or for ultimate wireless transmission by boat  10  to a remote operator. 
   Once bottom crawling vehicle  50  is on the sea floor, sensing system  64  is activated/used to (i) acquire/reacquire an object of interest, and (ii) provide inspection information (e.g., sonar data, video data) to one or more of computer  56 , computer  12  or a remotely-located operator so that an object of interest can be identified. If it is determined that the identified object should be neutralized, the appropriate control signals are issued to explosive charge control system  62  which maintains one or more explosive charge(s)  62 A. Explosive charges  62 A could be deployed from vehicle  50  by means of a release mechanism  62 B coupled to explosive charges  62 A. Another option would be for some or all of vehicle  50  to be left on the sea floor with charges  62 A. In this case, interface  52  could include a disconnection mechanism  52 A so that tether  44  can be uncoupled from vehicle  50  if vehicle  50  is to be made expendable. Disconnection mechanism  52 A can be actuated via a control signal received from boat  10 . 
   Referring now to  FIG. 4 , a (robotic) swimming vehicle  70  would be equipped in a fashion similar to bottom crawling vehicle  50 . Accordingly, common reference numerals have been used for those systems that would be identical or nearly identical as would be understood by one of ordinary skill in the art. In contrast, swimming vehicle  70  has an electrically-driven propulsion system  80  which could be realized by any conventional underwater vehicle propulsion system. Once on station, swimming vehicle  70  would be able to perform the same functions as bottom crawling vehicle  50  albeit in the water depths. 
   By way of example,  FIG. 5  illustrates a design for the present invention&#39;s surface vehicle that would be useful for carrying out the functions of the present invention. Specifically, a pontoon boat  100  has two or more pontoons  102  (e.g., three are illustrated) that provide for floatation thereof on the water&#39;s surface. In general, pontoon boats have a low profile which is advantageous for covert operations. A deck structure  104  is used to couple pontoons  102  to one another and is used to define hold regions  40  between pontoons  102 . In this way, vehicles  50  and/or  70  are stowed between pontoons  102  during travel to and from an area of interest. 
   The advantages of the present invention are numerous. The system is entirely unmanned thereby insuring that all operational personnel remain safe. By making multiple robotic crawling and swimming vehicles available for a given mission, the system can adapt to a wide variety of changing mission scenarios and operational environments. 
   Although the invention has been described relative to a specific embodiment thereof, there are numerous variations and modifications that will be readily apparent to those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described.