Abstract:
An underwater nuclear material reconnaissance system includes an underwater vehicle propelled/steered by a plurality of propulsion pods distributed thereabout. The underwater vehicle includes nuclear material sensors for generating sensor data indicative of the presence of nuclear material, a tunnel thruster for providing vertical thrust for the underwater vehicle, and a bi-directional communications cable deployable from the underwater vehicle. A remotely-located communications base station coupled to the bi-directional communications cable transmits control commands to the underwater vehicle and receives sensor data transmitted from the underwater vehicle.

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 underwater reconnaissance, and more particularly to an unmanned underwater reconnaissance system capable of sensing the presence of nuclear materials in the water, on a vessel or in a harbor, and then relaying the sensed information back to a remote location. 
     BACKGROUND OF THE INVENTION 
     The examination or reconnaissance of underwater sites for the purposes of determining the presence of nuclear materials is necessary in a variety of military and civilian situations. For example, military situations include intelligence gathering regarding underwater vessels or harbors. Civilian situations include examination of waters surrounding a damaged or sunken vessel that is powered by or carries nuclear material, and reconnaissance of, for example, the water near a nuclear power plant. Typically, such nuclear material underwater reconnaissance is carried out by divers equipped with various underwater sensors, lights, cameras, etc., to examine an area of interest. However, this approach places divers in jeopardy of detection in the case of covert operations, exposure to nuclear radiation, and the general perils associated with deep sea diving. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a system for performing underwater reconnaissance with the goal of detecting the presence of nuclear material. 
     Another object of the present invention is to provide a nuclear material underwater reconnaissance system that is unmanned. 
     Still another object of the present invention is to provide an unmanned nuclear material underwater reconnaissance system that can be operated from a safe stand off distance. 
     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 underwater nuclear material reconnaissance system utilizes a controllable underwater vehicle having a body and a plurality of propulsion pods distributed about and coupled to the body. Each propulsion pod has its own power source coupled to a propulsor. The underwater vehicle minimally incorporates nuclear material sensors for generating sensor data indicative of the presence of nuclear material, a tunnel thruster for providing vertical thrust for the underwater vehicle, and a bi-directional communications cable deployable from the underwater vehicle. A remotely-located communications base station coupled to the bi-directional communications cable transmits control commands to the underwater vehicle and receives sensor data transmitted from the underwater vehicle. 
    
    
     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 schematic side view of the underwater vehicle used in the underwater nuclear material underwater reconnaissance system in accordance with the present invention; 
     FIG. 2 is a front view of the underwater vehicle taken along line  2 — 2  in FIG. 1; 
     FIG. 3 is an isolated view of one of the underwater vehicle&#39;s self-contained propulsion pods; and 
     FIG. 4 is a schematic side view of the underwater nuclear material underwater reconnaissance system according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, and more particularly to FIG. 1, an unmanned underwater vehicle equipped for use in the present invention&#39;s underwater nuclear material reconnaissance system is shown and referenced generally by numeral  10 . Underwater vehicle  10  can be used in both military and civilian reconnaissance applications in which an underwater area of interest is to be examined for the presence of nuclear material. 
     Underwater vehicle  10  includes a main body portion  12  extending from fore to aft and a number of self-contained propulsion pods  14  coupled to main body portion  12 . Main body portion  12  can comprise an exterior housing for supporting a plurality functional modules to be described below. Alternatively, main body portion  12  can be formed by the plurality of functional modules, each of which could include a portion of an exterior housing such that main body portion  12  is formed when the modules are joined together. 
     Self-contained propulsion pods  14  are typically distributed symmetrically about main body portion  12  as illustrated in FIG. 2 where four such propulsion pods  14  are shown. As illustrated in FIG. 3, each of propulsion pods  14  includes an external waterproof housing  140  and a plurality of batteries  142  that power a propulsion system  144  to include a propeller  146 . The number and type of batteries used is not a limitation of the present invention. 
     The advantages of using multiple propulsion pods  14  in an underwater nuclear material reconnaissance system include the general advantage of making underwater vehicle  10  highly maneuverable as the speed of each propulsion pod can be individually controlled. For purposes of the present invention, this means that the nuclear material sensors (contained in module  22 ) can be optimally positioned at all times thereby minimizing the number of sensing “passes” required and minimizing the amount of time that underwater vehicle  10  must be on a site that is either potentially dangerous or hostile. 
     As mentioned above, main body portion  12  incorporates a number of functional modules for carrying out a nuclear material reconnaissance mission. A guidance and control module  20  would typically include a sonar system (not shown) and use sonar data to assist in the route guidance of vehicle  10 . The route guidance commands can be supplied manually/remotely or stored internally as will be explained further below. Nuclear material sensor(s) module  22  is provided to detect the presence of nuclear material which is typically in the water or onboard a vessel in the water. Further, in the case of extremely sensitive sensors or large amounts of nuclear material, sensor module  22  might also be able to detect the presence of nuclear material on dry land in a harbor. Such nuclear material sensors are well known in the art and will not be described further herein. A vertical thruster module  24  is provided in the central area of main body portion  12  so that underwater vehicle  10  can hover and quickly adjust its vertical position in the water. Typically, vertical thruster module  24  is a tunnel thruster, the particular design of which is not a limitation of the present invention. Various electronic systems and power supporting the modules in main body portion  12  are contained in an internal electronics and power module  26 . A fin/control surface assembly module  28  provide the necessary fins/control surfaces  28 A needed to manipulate underwater vehicle  10  as it is propelled through the water. A communication cable spool assembly module  30  houses a communications cable  30 A that is paid out during deployment of underwater vehicle  10 . Cable  30 A should be capable of bi-directional communication and is typically a fiber optic cable. 
     For improved navigation and/or intelligence gathering, underwater vehicle  10  can be equipped with additional systems. For example, one of propulsion pods  14  can incorporate imaging capability. More specifically, one of propulsion pods  14  can have an extension arm  40  coupled thereto. Arm  40  should extend radially out from main body portion  12  such that underwater vehicle  10  can run in the water while the outboard end of arm  40  extends out of the water. Mounted on the end of arm  40  is a video camera  42  so that underwater vehicle  10  can generate an above-water video image. A GPS antenna  44  can also be attached to arm  40  and provide GPS signals to guidance and control module  20 . 
     Another system that can be included as part of underwater vehicle  10  is a low-light condition imaging system. More specifically, one of propulsion pods  14  can incorporate an invisible light source/camera  46  capable of illuminating a low-light or no-light area of interest with invisible light and then imaging the area with a camera sensitive to the same invisible light. Although shown associated with the same propulsion pod  14  as video camera  42 , this need not be the case. 
     The complete underwater nuclear material reconnaissance system according to the present invention will now be explained with the aid of FIG. 4 where the system is referenced generally by numeral  100 . System  100  includes underwater vehicle  10  described above and a remotely-located operation control base station  50  which is typically located onboard a vessel or other platform (not shown) that launches/deploys underwater vehicle  10 . Base station  50  is manned/operated by personnel controlling and/or using underwater vehicle  10 . Accordingly, base station  50  includes a number of displays such as tactical display  52 , sonar display  54  and video display(s)  56 . Control commands for underwater vehicle  10  are input using a command input device  58  (e.g., keyboard, touch screen, voice activated controls, etc.) 
     In operation, underwater vehicle  10  is launched from a vessel/platform and directed to an underwater destination. As mentioned above, route guidance implemented by guidance and control module  20  can be pre-programmed, controlled manually from base station  50 , or be implemented by a combination of pre-programmed and manual maneuvers. For example, a pre-programmed route guidance could be used until vehicle  10  covered a certain distance (or was out for a specified time), at which point manual control of vehicle  10  could be used. For both pre-programmed and manual route guidance, guidance and control module  20  issues control commands to propulsion systems  144 , vertical thruster module  24  and fin/control surface assembly module  28 . While in route, GPS data and image data from cameras  42  and  46  can be transmitted over cable  30 A to base station  50 . More specifically, vehicle attitude/location and target location are displayed on tactical display  52  while sonar data can be displayed on sonar display  54 . Image data can be displayed on video display(s)  56 . Once in position for performing nuclear material reconnaissance, nuclear material sensor(s) module  22  is activated and underwater vehicle  10  is moved to inspect an area of interest. Sensor data gathered by module  22  is transmitted over cable  30 A to base station  50 . 
     The advantages of the present invention are numerous. The unmanned underwater nuclear material reconnaissance system will allow a dangerous underwater environment to be inspected from a safe stand off distance. The system can be used in covert military operations as well as civilian operations. The use of multiple propulsion pods allows the use of smaller batteries which are drawn down at a slower rate than larger batteries used in conventional underwater propulsion systems. Thus, the present invention can be used in longer missions and at greater stand off ranges than conventional underwater vehicles. 
     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.