Abstract:
A ground surface reconnaissance projectile includes a tube-launched 60 mm inert mortar round, which remotely relays reconnaissance and surveillance data back to an operator, after it has landed and uprighted itself. The types of collected data include for example, visual imagery of the target area in 360 degrees, acoustic target tracking and voice recognition, infra-red motion detection, and magnetic field disturbance sensing.

Description:
GOVERNMENTAL INTEREST 
     The invention described herein may be manufactured and used by, or for the Government of the United States for governmental purposes without the payment of any royalties thereon. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of ground sensors, and it more particularly relates to a ground surface reconnaissance projectile which is aerially deployable to a target location. 
     BACKGROUND OF THE INVENTION 
     Reconnaissance projectiles, including unattended ground sensors (UGS), have been developed for military use to satisfy the persistent need for reconnaissance, particularly in war situations. An exemplary need is for the prolonged deployment of the reconnaissance projectiles, while maintaining the survivability of the electronic components and sensors housed within the reconnaissance projectiles. 
     As used herein, a reconnaissance projectile is an unmanned monitoring platform that is often used for various military activities, such as terrain surveillance, troop movement, and target identification. The reconnaissance projectile can include a plurality of sensors. The reconnaissance projectile transmits the acquired sensor data, wirelessly, to a remote unit for analysis and use in field operations. 
     While numerous types of reconnaissance devices have been proposed, their main function is the general aerial reconnaissance over a target area. These reconnaissance devices may, in certain instances, be delivered to the target location by hand placement or by aerial deployment. Such delivery methods, while efficient for larger reconnaissance devices, may prove to be not feasible or inordinately costly and inaccurate to certain extent, particularly for distributing smaller reconnaissance devices over the target location within an enemy territory, or over a terrain that may be too difficult to reach by foot, such as in a mountainous region. 
     Higher accuracy in the placement of the reconnaissance devices is desirable to provide accurate peripheral surveillance of the target location. 
     There is therefore a need for a ground surface reconnaissance projectile which is completely inert, with an electronics package configuration that is designed to survive the gun launch and impact induced forces, while being able to persistently relay reconnaissance data over a long range, for an extended period of time after landing. The need for such a reconnaissance projectile has heretofore remained unsatisfied. 
     SUMMARY OF THE INVENTION 
     The present invention addresses the concerns of the conventional ground reconnaissance devices and presents a new remotely static reconnaissance projectile capable of performing ground level Intelligence, reconnaissance and surveillance (ISR), after the projectile has landed for an extended period of time, such as several days or longer. 
     The reconnaissance projectile has a wide array of sensor types and imaging systems, and can robustly classify targets of interest automatically. The present reconnaissance projectile is comparable to hand placed high values UGS with the significant tactical improvement of remote placement. 
     According to a preferred embodiment, the present reconnaissance projectile is a 60 mm mortar ground surface reconnaissance projectile, which is completely inert, with electronics package configuration designed to survive the gun launch and impact induced forces, while being able to relay reconnaissance data from a long range. 
     To this end, the present reconnaissance projectile includes a plurality of interconnected sections: a tail boom, a rear body, a main body, four leg hinge assemblies, and a nose cone (or nose). 
     The rear body houses a parachute that is deployed in flight to slow the projectile. After landing, the parachute is released and leg hinge assemblies are deployed to cause the projectile to uprights itself on four legs, thereby exposing a plurality of sensors and an antenna for communicating the collected data to an operator at a remote location. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention. The embodiments illustrated herein are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown, wherein: 
         FIG. 1  comprises  FIGS. 1A ,  1 B, and  1 C, wherein: 
         FIG. 1A  is a perspective view of a reconnaissance projectile according to the present invention; 
         FIG. 1B  is an enlarged view of a cutaway section of a leg hinge assembly that forms part of the reconnaissance projectile of  FIG. 1A ; 
         FIG. 1C  is an enlarged front view of the reconnaissance projectile of  FIG. 1A ; 
         FIG. 2  comprises  FIGS. 2A and 2B , wherein: 
         FIG. 2A  is a cross-sectional view of the reconnaissance projectile of  FIG. 1 , taken along line A-A of  FIG. 1C ; 
         FIG. 2B  is an enlarged cross-sectional view of a rear body that forms part of the reconnaissance projectile of  FIG. 2A ; 
         FIG. 3  comprises  FIGS. 3A and 3B , wherein: 
         FIG. 3A  is a cross-sectional view of the reconnaissance projectile of  FIG. 1 , taken along line B-B of  FIG. 1C ; 
         FIG. 3B  is an enlarged cross-sectional view of the rear body that forms part of the reconnaissance projectile of  FIG. 3A ; 
         FIGS. 4 through 15  are views of the reconnaissance projectile of  FIGS. 1 through 3 , that illustrate the sequence of operation of the internal deployment mechanism of the present invention; 
         FIG. 16  is a perspective view of the reconnaissance projectile of  FIG. 1  after landing and uprighting itself; and 
         FIG. 17  is an enlarged view of an antenna and support disc section of  FIG. 16 , illustrating the antenna in an uncoiled position. 
     
    
    
     Similar numerals refer to similar elements in the drawings. It should be understood that the sizes of the different components in the figures are not necessarily in exact proportion or to scale, and are shown for visual clarity and for the purpose of explanation. 
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     With reference to  FIGS. 1A and 1C , the present invention provides a ground reconnaissance device, such as a reconnaissance projectile  100  that is capable of performing ground level Intelligence, reconnaissance and surveillance (ISR) for an extended period of time after the projectile  100  has landed. The projectile  100  generally includes a plurality of interconnected sections: a fail boom  110 , a rear body  120 , a main body  130 , four leg hinge assemblies  140 ,  141 ,  142 ,  143 , and a nose cone  150 . 
     The tail boom  110  generally includes a plurality of fins  111 , as is known in the field. As a result, the tail boom  110  will not be described in greater detail. Similarly, the nose cone  150  is known in the field and will not be described herein in detail. The outer shape of the nose cone  150  is selected to maintain standard aerodynamic properties. 
     According to a preferred embodiment of the present invention, the projectile  100  is a 60 mm custom inert mortar projectile whose rear body  120  houses a parachute  700  that will be described later in greater detail in connection with  FIG. 7 . The parachute  700  is deployed in flight to slow the projectile  100 , in order to land softly and to prevent burial in soft terrain. 
     A bearing assembly  207  ( FIG. 2B ) forms part of the rear body  120 , and is used to allow the main body  130  of the projectile  100  to rotate freely relative to the parachute  700 . Such free rotation will ensure that the parachute cords  710  ( FIG. 7 ) does not become entangled. 
     As the projectile  100  descends, the parachute  700  drags the projectile  100  into a soft landing. After landing, the parachute  700  is released and the leg hinge assemblies  140 ,  141 ,  142 ,  143  are deployed. The projectile  100  uprights itself on four legs  1410 ,  1411 ,  1412 ,  1413  ( FIG. 14 ) of the respective leg hinge assemblies  140 ,  141 ,  142 ,  143 , exposing a plurality of sensors and an antenna for communicating the collected data to an operator at a remote location. Numerous different sensors can be used, including but not limited to optical and acoustic sensors. 
     Having summarily described the general operation of the projectile  100 , the design and operation of the projectile  100  will now be described in more detail. 
     With further reference to  FIGS. 2 and 3  ( FIGS. 2A ,  2 B,  3 A,  3 B),  FIG. 2A  is a cross-sectional view of the projectile  100  taken along line A-A of  FIG. 1C . The four leg hinge assemblies  140 ,  141 ,  142 ,  143  are generally similar in construction, function, and design, and are uniformly spaced along the periphery of the main body  130 . 
       FIG. 2A  illustrates two legs  1410 ,  1412  of the leg hinge assemblies  140 ,  142 , respectively, in a stowed position, so as not to adversely affect the aerodynamic performance of the projectile  100  during flight. Each leg hinge assembly  140 ,  142 , is shown to further include a leg spring  219 ,  221 , and a foam damper  220 ,  222 , respectively, whose function will be explained later in more detail. 
       FIG. 2B  is an enlarged view of the rear body  120  of  FIG. 2A  and further shows parts of the main body  130  and the tail boom  110  to which the rear body  120  is detachably connected. The rear body  120  houses the parachute  700 , which is shown in a stowed position, but which is automatically deployed in flight to slow the landing of the projectile  100 . 
     With further reference to  FIG. 7 , the parachute  700  is tethered by cords  710  to the bearing assembly  207  by means of, for example, pins  205 , but the tethering could alternatively be accomplished by a variety of other methods that are available or known. The bearing assembly  207  is used to allow a mortar body  215  of the main body  130 , to rotate freely with respect to the parachute  700 . This is done to ensure that the parachute cords  710  do not become entangled. 
     The parachute  700  is automatically deployed through an actuation mechanism  400  ( FIG. 4 ) that comprises the lead screw  209 , the axial piston  210 , the hollow shaft  212 , a rear set of ball detents  214 , a front set of ball detents  216 , a tail boom adapter  237 , a bearing inner race  238 , the rear spring  213 , and the front spring  218 . The actuation mechanism  400  is powered by the electric motor  208  ( FIGS. 2A ,  3 A,  3 B). The electric motor  208  forms part of the main body  130  and is connected to a lead screw  209  that extends and translates axially through the main body  130 . 
     The shaft of the motor  208  is pinned to the lead screw  209 . In turn, the lead screw  209  is threaded inside of an axial piston  210  that extends and translates axially and linearly, within a hollow shaft  212  of the rear body  120 , as the lead screw  209  is caused to rotate by the motor  208 . According to another embodiment, the shaft of the motor  208  can act as a lead screw, which could be achieved by having a threading motor shaft. 
     This linear motion of the axial piston  210  is achieved by pressing a pin  211  through the piston  210  and the hollow shaft  212  that houses the piston  210 . The pin  211  acts to prevent any rotational motion of the piston  210 . As the lead screw  209  rotates, and because the piston ( 210 ) rotation is restrained, the lead screw  209  is forced to translate axially within the hollow shaft  212 . The pin  211  serves multiple functions during gun launch. 
     As illustrated in  FIG. 4 , during gun launch, the pin  211  is seated against the bottom of a slot of the hollow shaft  212  and supports the inertial load of the piston  210 , to prevent the inertial load from being carried by the motor shaft. This state is referred to herein as “State  1 .” 
     As illustrated in  FIG. 5 , during flight and landing, as the actuation mechanism  400  is initiated, the pin  211  serves as a mechanical stop for the piston  210  and limits its travel until the pin  211  is bottomed on the front side of the slot of the hollow shaft  212 . This state is referred to herein as “State  2 .” As the projectile  100  lands, the pin  211  serves as a stop and carries the initial loading of the landing impact, so that the load resulting from the impact is not transmitted through the motor shaft, in order to prevent damage to the motor  208 . 
     In the assembled state, the rear body  120  is spring loaded by means of a rear spring  213 , and is locked into position via a rear set of ball detents  214 , that includes for example three detents. The detents  214  are located on the end of the piston  210  that is adjacent to the tail boom  110 . Sealing is provided to prevent damage resulting from high pressure gases and weather conditions. While not shown in the drawings, sealing can be achieved by a plurality of C-rings to prevent high pressure gases from entering the projectile rear body  120  and main body  130 . 
     The sequence of operation of the projectile  100  will now be described in more detail in connection with  FIGS. 4 through 15 .  FIG. 4  illustrates the projectile  100  during the initial stage of the flight, after firing, but prior to activation. The parachute  700  is shown in a stowed position. 
     At a desired or predetermined altitude of the flight, a control circuitry  390  ( FIG. 3A ) that is housed within the nose cone  150 , includes various electronic packages such as a transmitter, special sensors, timing circuits, and other circuitries. The control circuitry  390  sends an electronic control signal to the motor  208 , in order to actuate the actuation mechanism  400 . As illustrated in  FIG. 5 , when the motor  208  turns the lead screw  209  in the clockwise direction, the piston  210  is translated forward relative to the mortar body  215  in the direction of the arrow “L”, until it bottoms against the front of the slot of the hollow shaft  212 , as described earlier. 
     At this stage, the motor  208  is electronically shut off and the rear set of ball detents  214  are pushed radially inward, inside the hollow shaft  212  within the rear body  120 , by means of the rear spring  213 . In the above-referenced State  1 , the spring loaded rear body  120  is held in position by the rear set of ball detents  214 . The tail boom adapter  237  has a tapered surface that contacts the ball detents  214 . The ball detents  214  are captured between the tail boom adapter  237  and the piston  210 , to prevent the rear body  120  from being ejected under the action of the rear spring  213 . 
     When the piston  210  moves in the direction of the arrow “L” the ball detents  214  become free to fall into the hollow shaft  212 . As the piston  210  moves forward, it exposes a reduced diameter section of the piston  210  to the ball detents  214 , such that the ball detents  214  are captured between the tail boom adapter  237  and the piston  210 , to prevent the rear body  120  from being ejected under the action of the rear spring  213 . 
     As shown in  FIG. 5 , the detents  214  are then forced into the hollow shaft  212  until they bottom against the reduced diameter section of the piston  210 . The detents  214  are pushed in far enough until they no longer capture the tail boom adapter  237 , which enables the rear body  120  to be ejected. 
     Concurrently, as the piston  210  translates in the direction of the arrow “L” the front set of ball detents  216  get pushed radially outward through the hollow shaft  212  and gets captured between the bearing inner race  238  and the piston  210 . Because the ball detents  216  are captured, the bearing assembly  207  is secured to the main body  130 . The ball detents  216  retain the bearing assembly  207 , which is also preloaded with the front spring  218 . 
     Once in the aforementioned State  2 , the tail boom  110 , under the action of the preloaded rear spring  213 , is jettisoned, as shown in  FIG. 6 , in the direction of the arrow “M” causing the parachute  700  to be fully deployed.  FIG. 7  shows the parachute  700  in a fully deployed state. 
     With reference to  FIG. 8 , after the mortar body  215  has softly landed at the target location  888 , an on-board accelerometer  800  sensing no acceleration change, causes the control circuitry  390  to send a control signal to the motor  800  instructing the motor  800  to turn in the counter-clockwise direction. The counter-clockwise rotation of the motor  208 , causes the piston  210  to translate axially, rearwardly, relative to the mortar body  215 , in the direction of the arrow “N”. Concurrently, as the piston  210  translates in the direction of the arrow “N” the front set of ball detents  216  gets pushed radially inward through the hollow shaft  212  due to the spring force of spring  218 . and gets captured between the inner bearing race  238  and the piston  210 . 
     With further reference to  FIG. 9 , the relocation of the front set of ball detents  216  causes the front spring  218  to act on the bearing assembly  207  and jettisons it in the direction of the arrow “P” until it clears the hollow shaft  212  completely. The leg locking disc  217  includes a recess  917  that engages the four respective feet  1010 ,  1011 ,  1012 ,  1013  of the legs  1410 ,  1411 ,  1412 ,  1413  for retaining the legs  1410 ,  1411 ,  1412 ,  1413  in a locked position, as shown for example in  FIG. 8 . Concurrently with the ejection of the bearing assembly  207 , the leg locking disc  217 , which is a part of the bearing assembly  207 , is also ejected, thereby leaving the four legs  1410 ,  1411 ,  1412 ,  1413  free to deploy outwardly, along the arrow “Q”. 
     More specifically, while the leg locking disc  217  is engaged to the legs  1410 ,  1411 ,  1412 ,  1413 , it is spring loaded by means of a front spring  218 . As a result of the relocation of the front set of ball detents  216 , the disengagement of the legs  1410 ,  1411 ,  1412 ,  1413  from the leg locking disc  217  causes the front spring  218  to force jettison the leg locking disc  217 , the rear spring  213 , and the parachute  700 , along the arrow “P”, along the shaft  212 . 
     Consequently, and as further illustrated in  FIGS. 10-14 , the leg locking disc  217 , the rear spring  213 , and the parachute  700  are then detached from the mortar body  215 , and the four spring loaded legs  1410 ,  1411 ,  1412 ,  1413  are forced to open and to upright the mortar body  215  on the ground, as illustrated in  FIG. 14 . To this end, each leg, such as leg  1410 , is provided with a leg spring, such as leg spring  219 , which is designed to provide sufficient torque to force the corresponding leg  1410  to open, and further to upright the mortar body  215  as well as to support the weight of the mortar body  215  in the upright position. 
       FIG. 11  is a cross-sectional view of the main body  130 , the hinge assemblies  140 ,  141 ,  142 ,  143 , and the nose cone  150 , along line C-C of  FIG. 10 , following the ejection of the leg locking disc  217 , the rear spring  213 , and the parachute  700 . Two legs  1410 ,  1412  are shown being deployed by their respective leg springs  219 ,  221 , along the arrow “R”. 
       FIGS. 12 and 13  further illustrate the deployment sequence of the legs  1410 ,  1411 ,  1412 ,  1413 , wherein  FIG. 13  is a cross-sectional view of the main body  130 , the hinge assemblies  140 ,  141 ,  142 ,  143 , and the nose cone  150 , along line D-D of  FIG. 12 . 
       FIGS. 14 and 15  illustrate the main body  130  and the nose cone  150  of the projectile  100  in an upright position, ready to be activated for remote sensing.  FIG. 15  is a cross-sectional view of the main body  130 , the hinge assemblies  140 ,  141 ,  142 ,  143 , and the nose cone  150 , along line E-E of  FIG. 14 . 
     As explained earlier in connection with  FIG. 2A , each leg hinge assembly, i.e.,  140 , is provided with a foam damper, i.e.,  220 . Each foam damper, i.e.,  220 , surrounds a corresponding leg hinge  335  ( FIG. 1B ), to provide a smooth righting motion. 
     At this stage, the mortar sensors and electronic equipment module  810  ( FIG. 8 ) is turned on to remotely relay the reconnaissance data back to an operator. As illustrated in  FIGS. 16 and 17 , the data transmission is achieved by means of an antenna  1722 . The ejection of the leg locking disc  217  exposes the antenna  1722 . 
     The antenna  1722  is connected to the sensors/electronic equipment module  810  by means of a connector  1724 . The sensor/electronic equipment module  810  includes various sensors, as demanded by the specific applications of the projectile  100 , as well as several cameras lenses  326  ( FIGS. 3A ,  3 B,  16 ). 
     The camera lenses  326  are preferably located around the periphery of the mortar body  215 , at approximately 45 degrees from each other, and 45 degrees relative to the legs  1410 ,  1411 ,  1412 ,  1413  to create a 360 degree view around the mortar body  215 . 
     One or more additional microphones or sensors may be placed in the antenna cavity of the support disc cavity  1723  of the antenna  1722  ( FIGS. 16 ,  17 ). 
     The other electronic components of the projectile  100  may be located within the mortar body  215 , and may include, for example, 4 PCB boards  329  ( FIG. 3A ). All the PCB boards may be placed vertically inside the mortar body  215 , along the axial direction of the projectile  100 . The PCB boards may be supported in the transverse (up and down) direction can be mounted in a variety of configurations. The sensors, the electronic boards and components, and the power supply (i.e., batteries) are located inside the mortar body  215 . 
     It should be understood that other modifications might be made to the present design without departing from the spirit and scope of the invention.