Abstract:
A robotic vehicle is provided with an elliptical shaped housing, the housing having a circumferential track disposed about its midsection. The circumferential track is driven by a prime mover to rotate the housing and move it over a variety of different terrains. The vehicle is adapted to carry weapons systems for military application.

Description:
GOVERNMENT INTEREST 
     The invention described here may be made, used and licensed by the United States Government for governmental purposes without paying me any royalty. 
     BACKGROUND OF THE INVENTION 
     Robotic vehicles are becoming more prevalent in a wide variety of situations where it is desirable to minimize the exposure of humans to dangerous conditions. Commercial environments include hazardous chemical materials and nuclear materials where exposure by humans must be avoided. The military desires to use robotic devices as a means of probing into surrounding territory for the purposes of reconnaissance and force projection without the need to expose its valuable and highly trained troops. Thus, a military robotic vehicle might be equipped with sensors for identifying hostile forces, measuring terrain variables and deploying obstacles. A military robot may also carry one or more forms of munitions to protect the robot and to remove obstacles encountered by the robot. 
     One important characteristic for robotic vehicles used in military applications is the ability to operate in soft soils. A second important aspect is stability of the vehicle as it traverses uneven terrain. Yet another aspect is the quality of traction provided by the drive units of the vehicle. The drive units used must have limited skid or slip when driving the vehicle even in soft soil or uneven terrain. 
     At present, many robotic structures are modeled on multiple wheeled structures such as small cars. Such vehicles have problems with soft soil conditions where the wheels tend to become mired and the vehicle will become disabled due to the high pounds per square inch tire footprint. Also, such multi wheeled vehicles require a complex steering and control system making fabrication difficult and expensive. A multi wheeled structure also results in a high center of gravity when the vehicle is carrying weapons or sensors above the vehicle. 
     A second type of robotic vehicle is designed with various combinations of multi-legged structures to form a spider configuration. Spider configurations can move over small obstacles; however, such devices require complex control technology and are very slow moving since each leg must be moved individually. Such structures have a high center of gravity and are not well adapted to carry a load. Multi-tracked devices have also been proposed. Track laying devices also require complex control systems and the vehicle&#39;s ability to maneuver is dependent on chassis width of the vehicle and the length of the track. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to provide a robotic vehicle, which has a relatively low center of gravity even when carrying weapons, and or sensing devices. It is a further object of this invention to provide a robotic vehicle with good traction over a variety of various terrains. Further, it is an object of this invention that the robotic vehicle be able to maneuver in a relatively small area so as to provide sensing and targeting direction without substantial vehicle movement. 
     These and other objects are accomplished by a robotic according to this invention. The robotic vehicle has an elliptical shaped housing with major and minor axes, the elliptical housing having its major axis substantially parallel to the terrain the vehicle is traversing. The elliptical housing has a continuous circumferential track disposed about its midsection coaxial with the major axis of the elliptical housing. The circumferential track has a ground gripping texture on its outer surface to ensure good traction for the robotic vehicle over an extremely wide variety of soil and terrain conditions. 
     The robotic vehicle of this invention has an axle mounted along the elliptical housing major axis. The axle is journaled with the housing to allow the housing and axle to rotate freely with respect to one another during operation as is described in detail below. The axle serves as a principal means of support for vehicle systems and serves to consolidate the various parts of the robotic structure. Many of the parts of the vehicle will be attached to the axle and use it to function together. 
     The robotic vehicle has a prime mover mounted within the elliptical housing to provide power to rotate the elliptical housing about the major axis and also provide the power to operate other functions attached to the vehicle. The prime mover is suspended from the axle and depends downward from the axle towards the ground to a position below the axle and near the ground. Placing the prime mover low in the housing results in a lowered center of gravity for the entire housing and thereby the vehicle. 
     The prime mover is engaged with a transmission that transmits power to the system. The transmission comprises a first drive gear connected to the prime mover the first gear in turn engaging a second, larger internally toothed gear, the two gears forming an internal spur gear drive combination. The larger gear of the power transmission is engaged with the continuous circumferential track so that as the large gear rotates, the circumferential track will rotate about the axle of the housing. 
     In addition to the prime mover-power transmission-circumferential track drive mechanism, the robotic system of this invention has a compressed gas steering system located within the elliptical housing. The compressed gas steering system includes a compressor that draws power from the prime mover and delivers ambient air under pressure to a gas storage tank for storage and later use. Sensing means will activate the compressor to maintain the desired pressure in the gas storage tank. A gas delivery system is connected to the gas storage tank for the delivery system having gas lines fluidly connected to the storage tank, with control valves as part of the delivery system. The delivery system provides compressed air to the rest of the system as needed. The compressed air system has jet nozzles located on each end of the axle; the jets have control means to change their orientation to provide additional steering and maneuverability. The control valves in the gas delivery system provide the required amounts of compressed air to the jets when it is desired to effect a rapid or tight radius turn. 
     Braking members are provided which can apply a braking force to the axle to promote turning, control speed, and hold the robot in position for firing of its weapons. The brakes can also be used to hold the robot in a fixed position for reconnaissance and use as a remote sensing station. 
     The second major portion of the overall robotic weapons system of this invention is a platform adapted to carry weapons and/or other functional units such as sensors, and communication units. The platform containing the desired items is supported by and journaled on the axle of the housing. The platform has a load-carrying surface located above the elliptical housing with respect to the surface on which the housing is located. The load-carrying surface is used to support the various mission critical gear that is needed to determine the terrain and locate possible military targets within the range of the robot. The load-carrying surface may also carry a radio antenna, and receiving devices for global positioning systems and other electronic equipment. 
     The weapons portion of the present system of this invention includes weapons pods mounted on the ends of the axle. The weapons pods will have a positioning motor that can rotate the weapons pod about the axle to the desired angle of elevation for firing. 
     Counterweight shells are attached to the axle opposite the weapons platform. The counterweight shells are adapted to carry a portion of the electronic systems, which will conserve volume and provide additional weight to the compounds. The shells will also contains a quantity of liquid to provide an adjustable component to the ballast for the weapons system. 
     The robotic vehicle has a liquid control system, which includes a pump, fluid lines and valves. The liquid control system fluidly connects the counterweight shells and is responsive to signals from the vehicle control means to move liquid between the counterweights. This will change the balance of the elliptical housing with respect to the circumferential tread in order to effect the robot&#39;s direction of travel. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawing: 
     FIG. 1 is a schematic front view of one embodiment of this invention; 
     FIG. 2 is front view in partial section of the embodiment of FIG. 1; 
     FIG. 3 is an enlarged view of a portion of a driving gear of FIG. 2; and 
     FIG. 4 is partial perspective view of the embodiment of FIG.  1 . 
    
    
     DETAILED DESCRIPTION 
     Referring to the accompanying drawing wherein like numerals refer to like parts, a robotic weapons system is designated generally  10  and has an elliptical housing  12  formed by two symmetrical domes  14 . The resulting elliptical housing  12  has major and minor axes, the elliptical housing being deployed and powered, as described below, so as to rotate about the major axis. A circumferential track  16  is disposed coaxially with the major axis between the domes  14  about the midsection of the elliptical housing  12 . The circumferential track  16  is formed with a ground gripping texture on its outer surface to provide good traction for the robotic system over a wide variety of ground and terrain conditions. 
     The robotic weapons system  10  has an axle  18  located coaxially with the major axis of elliptical housing  12 . The axle  18  is journaled in an aperture in the domes  14  using bearings  20  at the ends of the axle that allow the housing  12  and axle to rotate freely with respect to each other. Them axle  18  can be thought of as the spine of the weapons system  10  to which components are connected and through which the components can communicate. The axle  18  is formed as a hollow tubular structure with an interior cavity through which various portions of the system can communicate as described in detail below. 
     A prime mover designated generally  22  provides the power for movement of the elliptical housing  12  and also for operation of the other system functions. The prime mover  22  is mounted within the elliptical housing  12  by being suspended from the axle  18 , the prime mover being near the ground. This creates a lowered center of gravity for increased stability. The prime mover  22  could be a hydrocarbon burning type structure in which case the prime mover accessory equipment would contain a small engine, fuel tank, fuel control and radiator. However, where desired the prime mover  22  could be an electrical drive system with an associated electric motor, battery pack and electrical controls. In the future it is contemplated that the prime mover  22  could utilize fuel cell technology to provide a quiet exhaust free power source or even advanced solar panel structures in combination with a battery as part of the electric motor drive. 
     The prime mover  22  is shown connected to an internal spur gear that serves as a transmission. The transmission has a plurality of first drive gears  24 , mounted on shafts  26  powered by the prime mover  22 , the gears is engaging a second set of larger, internally toothed gears designated generally  28  the combination forming an internal spur gear drive mechanism. As shown enlarged in FIG. 3, the internally toothed gears  28  are composed of two toothed gear tracks formed as flanges  30 , the flanges being coaxially aligned with the axle  18  and extending from a center web  32  between the tracks. The innermost toothed flange  30  closest to axle  18 , is connected to a plurality of radially extending spokes  34 , at a first end of each spoke. The second end of each spoke is connected to an associated hub bearing  36  mounted on the axle  18 , as shown best in FIG.  4 . The drive gears  24  and associated shafts  26  act as a supporting framework to position the power pack between the larger internally toothed gears  28 . 
     The larger, internally toothed gear  28  of the power transmission is connected to the continuous circumferential track  16 . Thus, as the prime mover  22  rotates shafts  26 , and the spur gears  24 , the center of gravity of the prime mover  22  will tend to rise causing the internally toothed gear  28  to revolve so as to bring the prime mover&#39;s center of gravity back to it&#39;s lowest position. The internally toothed gear  28  rotation in turn causes the circumferential track  16  and the associated housing domes  14  to rotate moving the entire vehicle in the desired direction. 
     In addition to the drive system detailed above, a compressed gas steering system, powered by the prime mover, is provided for tight turns and finer rotational control of the robotic vehicle  10 . The compressed gas steering system includes a compressor  70  and gas storage tank  72  with a control system  76  provided to maintain the gas storage tank  72  at the desired pressure and ready for use. The gas storage tank  72  is in turn fluidly connected to a pair of jet nozzles  78  located on the ends of axle  18 . The fluid connection between the gas storage tank and jet nozzles is controlled by various sensors and valves so as to maintain the desired fluid pressure under normal operating conditions. The system will allow the flow of gas to the jet nozzles when it is desired to cause the robotic vehicle to rotate rapidly about its vertical axis in order to bring the weapons system into alignment or move the robot vehicle about an obstacle. 
     Frequently, it would be desirable to have the robotic vehicle remain firmly in position to remain on watch status and not consume more minimal amounts of energy. In order to maintain a fixed position, brakes  40  are provided, one example of a suitable brake set being the common caliper type disc brakes. Such a structure with a rotor  42  being attached to the axle  18  being engaged by a caliper  44  mounted on internally toothed gear  28 . The brakes  40  could be responsive either to sensors located on the robotic vehicle or applied from a remote location. When the brakes  40  are engaged, the robotic vehicle could maintain a position even on inclines that would normally cause the vehicle to move downward. Also, the brakes can be engaged in order to hold the robotic vehicle in position when it is desired to activate a weapons system which will normally cause recoil forces tending to force the vehicle backwards. 
     The robotic vehicle  10  system has a platform  60  with a rectangular plate  62  located generally above the elliptical housing  14  with respect to the ground on which the robotic vehicle  10  is moving. The platform  60  is connected to the robotic vehicle  10  and mounted on a pair of support arms  64  that extend upward from the axle  18  at a slight angle to vertical forming a V. 
     The vehicle has a pair of counterweights  66  attached to the axle  18  within the housing  12  to provide counterbalancing forces and maintain the platform  60  above the housing  12 . The counterweights  66  have as their primary function maintaining the platform  60  and its supports in position relative to the elliptical housing  12  so that the sensors and associated platform are always located above the housing. As noted before the counterweights  66  provide the primary means for holding the weapons platform in an upright position above the elliptical housing  12 . However, the counterweights  66  of this invention have other uses. The counterweights  66  are reservoirs which are suspended from the axle  18  by means of a fluid connection  80  that is in turn connected to a fluid control system  82  that operates a valve  84  between the counterweights. A portion of the counterweights  66  total mass is a liquid that can be moved between the counterweights in response to signals either from the onboard sensors or from a remote controller. Moving fluid from one counterweight  66  to the other will redistribute the balance of the elliptical housing  12  and cause it to turn towards the counterweight having the greater mass. 
     In addition to providing a weight distribution and steering capacity, the counterweight reservoirs can provide a protected environment in which a portion of the electronic systems, such as computer control and other electronic measurement devices can be stored. The presence of liquid will provide a certain degree of cooling to the electrical systems enhancing their effectiveness and longevity. 
     As shown, the robotic vehicle  10  has a weapons system  50  journaled on the axle  18 . The weapons system  50  shown comprises four pods  52  suitable for launching rockets or similar munitions. The pods  50  are rotatably mounted on the upright supports  64  of the weapons platform  60  and have an associated positioning motor  56  to rotate the pods  50  to position the pods for firing. The positioning can be done using either onboard sensors and targeting algorithms or manually aimed from a remote controller. 
     Various alterations and modifications will become apparent to those skilled in the art without departing from the scope and spirit of this invention and it is understood this invention is limited only by the following claims.