Abstract:
A towing assembly is mounted to the rear of a robotic vehicle. The assembly has motors and hydraulic cylinders which are actuated to manipulate a lunette, pintle or other hitching element. Manipulation of this hitching element brings it into connection with a complementary element on a vehicle to be towed. The motors and cylinders can be remotely controlled and a camera on the robotic vehicle allows a human operator at a remote site to monitor the operation of the towing assembly.

Description:
GOVERNMENT USE 
     The invention described here may be made, used and licensed by the or for the U.S. Government for governmental purposes without paying me any royalty. 
     BACKGROUND 
     Robotic vehicles have long been studied by military organizations because they provide a way to accomplish dangerous missions without risk to human life. For example, robotic vehicles have been developed for mine clearing and recovery of unexploded artillery shells on firing ranges. Another duty that could be advantageously performed by robotic vehicles is recovery of stranded vehicles in a battle space. Such duty not only involves risks of land mines and enemy fire, but could also involve the risks presented by nuclear, biological and chemical warfare. For the robotic vehicle to recover other vehicles it needs a mechanism to adjust the position of a lunette, hook, pintle or like towing hardware once it has arrived in front of the stranded vehicle. It also needs a mechanism to detect whether the positioning of the hardware is proceeding as desired and whether a successful connection with the stranded vehicle has occurred. My invention comprises an electro-hydraulic towing assembly that manipulates the aforementioned towing hardware into connection with complementary hardware of a vehicle to be towed. My invention also has means to monitor and control the towing assembly&#39;s operation. 
     SUMMARY 
     The towing assembly includes a lunette or other hitching element connected to a primary hydraulic cylinder. Actuating the cylinder moves the lunette closer or further from a complimentary hitching element on another vehicle. The cylinder is mounted to a post so that it has two degrees of rotational freedom. Thus, the cylinder can swing up and down in a vertical plane or can swing side-to-side in a horizontal plane in order to move the lunette to a desired position. The side-to-side swinging motion of the cylinder is accomplished by a reversible electric motor mechanically connected, directly or indirectly, to the cylinder. The vertical swinging of the primary cylinder is accomplished by a secondary hydraulic cylinder connected thereto. The post is translatable along a guideway so that the post and cylinder can be moved together closer or further from the hitching element on the other vehicle. The translation of the post and cylinder is done by a motor mechanically connected to the post. 
     The overall invention, of which the towing assembly is part, has a camera on the robotic vehicle. The camera views the towing assembly and sends video signals to a human operator at a station remote from the robotic vehicle, whereby the operator can monitor the assembly&#39;s operation. The station has input devices, such as joysticks or levers, whose manipulation results in signals that control the operation of the motors and cylinder. By using the camera and the input devices, the operator can keep using the towing assembly to reposition the lunette until it connects with the complementary hitching element on the other vehicle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a simplified view of a system having an electro-hydraulic towing assembly on a robotic vehicle and a remote station controlling the vehicle. FIG. 2 is a side view of an electro-hydraulic towing assembly. FIG. 3 is a cross-sectional view of a channel of the towing assembly showing how one of the assembly&#39;s motors is disposed in the channel. FIG. 4 is a semi-schematic diagram of the system having the electro-hydraulic towing assembly on the robotic vehicle and the remote station controlling the vehicle. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows the overall system in which the electro-hydraulic towing assembly functions wherein a robotic vehicle  12  is controlled from a station  14 , which is typically remote from vehicle  12  but which may be aboard the vehicle if desired. Vehicle  12  has a towing assembly  10  affixed either directly to the vehicle frame or to a vehicle component  11  that is solidly connected to the frame. Vehicle  12  has a camera  16  aimed at assembly  10  and has antenna  18  by which video signals from camera  16  are transmitted to station  14 . Station  14  has a complementary antenna  20  for sending signals to vehicle  12  and receiving signals therefrom. 
     It is contemplated that a human driver  22  in the station will control vehicle  12  and the operator will view output from camera  16  on a monitor screen  24 . For that reason, the station includes one or more operator output device such as a joystick  26  and lever  27  mounted on console  28 . A mouse, keyboard, switches or any other conventional input mechanisms can be used instead of the lever or the joystick. Movement of lever  27  and joystick  26  generates control signals to govern the operation of towing assembly  10 . As an option, driver  22  may be an artificial intelligence unit instead of a human. 
     FIG. 2 shows details of the towing assembly  10 , which includes a guideway preferably in the form of grooved channel  30 , a cross sectional view of which is shown in FIG.  3 . Rails or keyways can, in appropriate cases, be used instead of a channel. Channel  30  is typically affixed to a vehicle component  11  that is solidly connected to the vehicle&#39;s frame, but channel  30  can also be affixed directly to the frame. Channel  30  defines grooves  32 , which accommodate complementary ridges or edges of a sliding member that translates along the channel. Typically such a sliding member will be a base plate  34 , whose edges fit in grooves  32 . Mounted on the bed of the channel is a reversible electric motor  36  that translates plate  34 . Motor  36  is offset from the longitudinal axis of the channel as most clearly seen in FIG. 3, where motor  36  is represented by a dashed outline. Extending from motor  36  is worm gear  38 , which mates with a threaded boss  40  projecting upward from the edge of plate  34 , whereby actuation of motor  36  translates plate  34  toward or away from the motor. 
     A post  42  is rotatably mounted to plate  34  by a mounting unit  52  comprised of an arrangement of ball bearings and a race that accepts one end of the post. The post is also journalled in a rotation collar  53 , which is fixed to the side of plate  34  facing away from unit  52 . Fixed to and encircling post  42  is ring gear  44  whose teeth engage complementary splines on shaft  46 . A reversible electric motor  48  is fixed to a rigid strut  55 , which itself is affixed to plate  34 . Motor  48  drives shaft  46  and thereby turns gear  44  and post  42  in either direction. 
     Two elements extend away from post  42 , one being a primary hydraulic power cylinder  54  and the other being a secondary hydraulic power cylinder  56 . Cylinder  54  is swingably connected to post  42  by a hinge comprised of a pair of bracket ears  58  that pivotally engage a flange  60  extending therebetween. Cylinder  56  is similarly connected to post  42  by a hinge comprised of tabs  61  that pivotally engage flange  62  extending therebetween. Protruding from cylinder  56  is translatable rod  64  having a flange  66  at one end. Flange  66  is pivotally engaged to tabs  68 , which are fixed to cylinder  54 . Actuation of cylinder  56  extends or retracts rod  64  so that cylinder  54  swings upward toward post  42  or downward away from it, thereby raising or lowering cylinder  54 . Optionally, cylinder  56  can be replaced by an electric motor having a conventional internal worm gear arrangement to extend or retract rod  64 . 
     Cylinder  56  is shown as having two ports,  70  and  72 , by which hydraulic fluid enters and leaves. It is contemplated that pressure will need to be applied only through port  70 , when it is desired to extend rod  64 . When pressure is removed from port  70  in any suitable, conventional fashion, the weight of cylinder  54  will cause rod  64  to retract into cylinder  56 . As an option, pressure can be applicable through port  72  as well, whereby cylinder  56  operates as a conventional double acting cylinder. Cylinder  56  is shown schematically in FIG. 4, where it is communicated to any known pressure supply mechanism, such as pump  88 , through a fluid switch  90 . 
     Cylinder  54  is a double acting cylinder and it has two hydraulic connection ports,  78  and  80 . Pressurization through port  78  will, in conventional fashion, cause lunette or eye  82  to translate away from cylinder  54 . Pressurizing port  80  will conversely retract eye  82  toward cylinder  54 . Pressure through ports  78  and  80  may be supplied by a pump, shown schematically at  84  in FIG. 4, or any other known pressure supply mechanism. A conventional fluid switch  86  (FIG. 4) controls pressure flow to the ports. The cooperative action of hydraulic cylinder  54  with motor  36 , motor  48  and cylinder  56  will maneuver eye  82  into engagement with hook  83  or like device on a trailer vehicle (not shown) to be towed by robotic vehicle  12 . It will be appreciated that eye  82  may be replaced by a hook, pintle, trailer hitch ball or other inter-vehicle hitching element. 
     The operation of towing assembly  10  in the overall system where it functions is explained in conjunction with FIG.  4 . Let us assume that robotic vehicle  12  has arrived at the location of a trailer vehicle and has been positioned such that eye  82  is near hook  83 . Driver  22  then begins to use the motor control mechanism  92  and the hydraulic control mechanism  94  to maneuver eye  82  into the engagement with hook  83  shown in FIG.  2 . Motor control mechanism  92  includes joystick  26  and the means to send signals from the joystick along communication path  96 , which includes the radio transmission path between antennas  18  and  20  in FIG.  1 . The effect of signals from the motor control mechanism is to turn a given motor in one direction, turn that motor in the opposite direction or stop that motor&#39;s turning. It is contemplated that manipulation of joystick  26  will also send signals to hydraulic control mechanism  94 , which in turn sends hydraulic control signals along paths  98   c  and  98   d . These paths include the radio transmission paths between antennas  18  and  20 , and signals sent therealong control pump  88  and switch  90  respectively. In summary, manipulation of joystick  26  affects hydraulic cylinder  56  as well as motor  36  and motor  48 . 
     Hydraulic control mechanism  94  also includes lever  27  and the means to send signals along communication paths  98   a  and  98   b , which include the aforementioned radio transmission path. Pump  84  starts or stops in response to signals incoming along path  98   a  and switch  86  responds to signals from path  98   b . Likewise, pump  88  starts or stops in response to signals incoming along path  98   c  and switch  90  responds to signals from path  98   d . As driver  22  manipulates joystick  26  and lever  27 , he sees the effect of his manipulations via signals sent by camera  16  along communication path  99  to monitor  24  (FIG.  1 ). 
     I do not wish to be limited to the exact details of construction or method shown herein since obvious modifications will occur to those skilled in the relevant arts without departing from the spirit and scope of the following claims.