METHOD AND APPARATUS FOR THE CLEARING OF MINEFIELDS

Abstract: Clearance of a minefield is effected using first and second ground-engaging drive units (63 and 64), each of which includes a milling or grinding drum (6). The first drive unit (63) is connected to the front of a multi-purpose vehicle or tractor (62) and the second drive unit (64) is connected to the rear of the vehicle or tractor (62) to form a mine clearance apparatus which can be driven over the land to be cleared of mines with the vehicle or tractor (62) supported clear of the ground by the first and second drive units (63 and 64). The milling or grinding drum (6) of the first drive unit (63) grinds up the surface vegetation and the milling or grinding drum (6) of the second drive unit (64) grinds up a layer of soil and any anti-personnel mines contained therein.

Description: METHOD AND APPARATUS FOR THE CLEARING OF MINEFIELDS Field of the Invention This invention relates to a method and apparatus for the clearing of minefields, and is particularly concerned with the clearance of buried anti-personnel mines. Current methods for the clearance of minefields, particularly after the minefields have been laid for a number of years, involve a number of time-consuming operations. In particular, it is necessary to clear any vegetation which has grown since the minefield was laid prior to the removal or destruction of the land mines using explosive charges. The mines are located only after careful removal of the vegetation, followed by probing of the soil with mine probes. It is a particular disadvantage of the conventional clearance methods that probing using probes and destruction using explosive charges often result in additional safety hazards for the personnel carrying out the mine clearance operation. Another disadvantage of the conventional methods is that chemical pollution arising from extensive use of explosives can produce degradation of the agricultural properties of the soil to such an extent that the land which has been cleared is not suitable for agricultural use for many years. It is accordingly an object of the present invention to provide an improved method for the clearance of anti-personnel mines and improved apparatus for the carrying out of said method. Summary of the Invention According to a first aspect of the present invention there is provided a method for the clearance of anti-personnel mines, the method comprising:- a) providing a first ground-engaging drive unit which includes a milling or grinding drum, b) providing a second ground-engaging drive unit which includes a milling or grinding drum, c) connecting the first drive unit to the front of a vehicle and the second drive unit to the rear of the vehicle to form a mine clearance apparatus, and e) driving the mine clearance apparatus over the land to be cleared in such manner that the milling or grinding drum of the first drive unit grinds up the surface vegetation and the milling or grinding drum of the second drive unit grinds up a layer of soil and any antipersonnel mines contained therein. According to a second aspect of the present invention there is provided apparatus for use in the clearance of a minefield, the apparatus comprising first and second ground-engaging drive units each of which includes a milling or grinding drum, and each drive unit being provided with connector means such that the first drive unit can be connected to the front of a vehicle and the second drive unit can be connected to the rear of the vehicle to form an apparatus which can be driven over the land to be cleared in such manner that the milling or grinding drum of the first drive unit grinds up the surface vegetation and the milling or grinding drum of the second drive unit grinds up a layer of soil and any anti-personnel mines contained therein. The vehicle is preferably connected to the first and second drive units in such manner that, when the apparatus is being driven over the land to be cleared of mines, the vehicle is supported clear of the ground by said first and second drive units. The first drive unit preferably includes a detector for the detection of buried objects larger than anti-personnel mines. The first drive unit preferably includes blockage prevention means to prevent clogging of the milling or grinding drum due to excessive vegetation, wet soil or other adverse conditions. The first and second drive units preferably each include a blast damage reduction device to obviate damage due to blast energy from exploding anti-personnel mines. The second drive unit preferably includes a soil filtering device for preparing the de-mined soil for agricultural seeding. An integrated drive and governor system is preferably provided for moving the apparatus over the ground to be cleared under the power of the prime mover of the vehicle. An integrated steering and fixing system is preferably also provided. Means are preferably provided on the first drive unit for projecting ground-up vegetation upwardly and rearwardly so that it is applied on top of ground-up soil discharged from the second drive unit. The first and second drive units preferably include many common components to facilitate repair and maintenance. Thus, according to a third aspect of the present invention there is provided a drive unit which includes a milling or grinding drum, connector means for connection of the drive unit to the front or rear of a vehicle so that, when driven over the land to be cleared the milling or grinding drum grinds up either the surface vegetation or a layer of soil and any anti-personnel mines contained therein, and a blast damage reduction dev ce to obviate damage due to blast energy from exploding anti-person r, el mines. Brief Description on the Drawings Figure 1 is a perspective view of a drive unit with cut-out sections showing component parts of the drive unit, Figure 2 is a cross-sectional view of the forward-looking detector, with ground-speed radar and processing electronics, Figure 3 is a sectional view of a front drive unit, Figure 4 is a sectional view of the milling or grinding drum used for lifting and destroying buried land mines or vegetation, Figure 5 shows a blockage prevention device and a blast damage reduction device, Figure 6 shows a soil filtering system, Figure 7 is a sectional side view of the integrated steering and fixing system of the mine clearance apparatus, Figure 8 is a plan view of the integrated steering and fixing system looking from the base to the top, Figure 9 is an overview of the integrated drive and governor system of the apparatus, and Figure 10 shows a particular application of the apparatus being used to remove vegetation and clear anti-personnel mines. Description of the Preferred Embodiment The drive unit shown in Figure 1 is intended to form part of an apparatus, as shown in Figure 10, for clearing vegetation and antipersonnel mines. The drive unit includes a main frame consisting of left and right side covers 1 and 2 joined by a central box-section beam 3. The frame houses two driving rollers 4 and 5 located at the front and the rear of the frame and a milling or grinding drum 6 located at the mid-point of the frame, directly below the central beam 3. A plurality of tungsten carbide teeth 7 are attached to the milling or grinding drum 6. The milling or grinding drum 6 is arranged so that, as viewed in Figure 1 , it rotates in a clockwise direction. A multi-sectioned shear bar 8 is fixed to the central box-section beam 3 above the milling or grinding drum 6. An integrated steering and fixing device 9 is also attached to the central box-section beam 3. In Figure 1 , the front drive roller 4 is shown cut away to illustrate the location and mounting of a forward looking detector 10 which is held in the centre of the roller 4 on a fixed shaft 11. A blast shield 12 is located above and to the left of the milling or grinding drum 6. The shield 12 is used to dissipate energy from any occurrence of detonation during the lifting and destruction of antipersonnel mines. The blast shield 12 is operated upon by the combination of two springs 13 (only one of which can be seen in Figure 1) attached to the left and right side covers 1 and 2, and a side crank mechanism 14. The blast shield 12 is held above and to the left of the milling or grinding drum 6 by four solid straps 15 mounted on the left and right side covers 1 and 2. Figure 1 also shows the location of a soil filtering system 16. The side cover 2 is shown cut away to illustrate the soil filtering system 16 attached to the central box-section beam 3 directly behind the milling or grinding drum 6. Figure 1 also shows the location of two hydraulic motors 17 and 18 which are used to drive the front and rear drive rollers 4 and 5. Two other hydraulic motors 19 (only one of which can be seen in Figure 1 ) are used to drive the milling or grinding drum 6. Independent drive systems are thus provided for the two drive rollers 4 and 5 and for the drum 6. As shown in Figure 2, the forward-looking detector 10 is connected to the fixed shaft 11 by a fixing support 20. A ground speed radar system comprising a transmitting device 21 and a receiving device 22 is mounted on the forward-looking detector 10. The radar system 21 , 22 is used to send ground travel speed information to a global positioning device and computer 26 on board a multi-purpose vehicle or tractor 62 (see Figure 10). An electronic unit 25 is mounted on the fixing support 20 and a key-way 23 is cut into the fixed shaft 11 to receive the electrical cables 24 interconnecting the electronic unit 25 and the global positioning device and computer 26. As shown in Figure 3, the fixed shaft 11 , on which the forward- looking detector 10 is mounted, is contained within the front roller 4. The shaft 11 is attached by means of a fixing plate 27 to the side cover 1 and carries a bearing 28 on which the front drive roller 4 is mounted. This arrangement allows the hollow front drive roller 4 to rotate while the shaft 11 remains fixed relative to the side cover 1. The end of the fixed shaft 11 remote from the side cover 1 is connected to a second shaft 30 by a spigot coupling 29. The second shaft 30 is supported by means of a bearing 68 mounted on the side cover 2. The second shaft 30 is fixed to the front drive roller 4 and to the output element of the front hydraulic motor 17. The front hydraulic motor 17 thus rotates the second shaft 30 and the front drive roller 4, while the fixed shaft 11 remains stationary. Figure 4 shows one end of the milling or grinding drum 6 which, in the case of a front drive unit, is used to mulch vegetation or soil and, in the case of a rear drive unit, to grind up any anti-personnel mines which are encountered. There is a hydraulic motor 19 at each end of the drum 6 and the hydraulic power to the two motors 19 is supplied by the multi-purpose vehicle or tractor 62. The output element of each hydraulic motor 19 is connected to a respective shaft 31 fixed to the milling or grinding drum 6 by means of a fixing plate 34. A plurality of high-speed tungsten carbide tips 7 are carried by the milling or grinding drum δ and the arrangement is such that, as the drum 6 is rotated, all the materials which are encountered, e.g. the soil, vegetation and mines, are ground up as they are forced past the shear bar 8 by the tungsten carbide tips 7. All the soil and vegetation is converted into mulch and the mines are ground into pieces or detonated. Figure 4 also shows part of the crank and slider mechanism 14, the blast shield 12 and a bearing 32 which is carried by the left cover plate 1 and supports one end of the shaft 31. Figure 5 illustrates the mode of operation of the blockage prevention system which acts as an automatic governor for the milling or grinding process. It includes the blast shield 12 which is supported from the left and right side covers 1 and 2 by four solid pivoted straps. Two of the straps, i.e. straps 15 and 35, are shown in Figure 5. Counter-torque on the hydraulic motor 19, caused by an increase in the volume of soil or vegetation being mulched, or by a blast from an anti-personnel mine, will cause the crank and slider mechanism 14 to move and lift the blast shield 12 away from the milling or grinding drum 6. This movement is in a direction at right angles to the surface of the drum 6. Movement of the blast shield 12 is detected by a position sensor 36 located on the slider component of the crank and slider mechanism 14. The output of the position sensor 36 is used to reduce the hydraulic power inputs to the hydraulic motors 17 and 18 which drive the front and rear drive rollers 4 and 5. The resulting reduction in forward speed and lifting of the blast shield 12 alleviates clogging and the effects of blast damage. Figure 6 shows the soil filtering system 16. The system 16 includes a number of spring filter rods 37 only one of which is shown in Figure 6. The other rods 37 are arranged in parallel relationship with the rod 37 shown in Figure 6. The rods 37 are secured to a plate which has a hinge 38 which can move through pre-set parameters. When the machine is in operation, the soil filter rods 37 are able to move altogether on the hinge 38 and individually (because of the spring characteristics). The rods 37 thus act to filter the material being forced out through the gap between the teeth 7 on the drum 6 and the shear bar 8. The action of each individual rod 37 and the change in angle of the hinge unit, moving all the rods 37 through the same angle, is automatic, depending on the quantity and condition of the soil being ground in the milling or grinding process. As the soil is passed through the gaps between the filter rods 37, the soil is separated and sieved preparing the soil so that it is ready for agricultural seeding. Figures 7 and 8 show the integrated steering and fixing system 9 which allows the device to be fixed and controlled hydraulically by either a multi-purpose vehicle or tractor 62. The steering and fixing system allows controlled hydraulic movement in all three axes, i.e. steering left and right movements, crowd and tilt and roll back and forth. The steering system includes a swivel ball joint 39 which is attached to two plates 40 and 41 which have standard three-point linkage coupling connections 42 and 43. These coupling connections 42 and 43 provide the connections to the multi-purpose vehicle or tractor 62. The left side plate 40 has a single coupling lobe, while the right side plate 41 has double coupling lobes 42 to allow connection to either the front or back of the multi-purpose vehicle or tractor 62. Four hydraulic rams 44, 45, 47 and 48 act between the side plates 40 and 41 , two of the rams 44 and 45 being shown in Figure 7. The hydraulic rams 44, 45, 47 and 48 are held by eight flexible couplings, one of which is indicated as 46 in Figure 7. The underside of the integrated steering and fixing system is shown in Figure 8 and the arrangement is such that steering movement to the right and left is controlled by hydraulic rams 44 and 47. Reducing the effective length of the piston of hydraulic ram 44 and increasing the length of the piston of hydraulic ram 47 will cause plate 40 to angle in one direction. Reversing the operation of the two hydraulic rams 44 and 47 will cause plate 40 to angle in the opposite direction. Crowd and tilt movement can be effected by movement of a further hydraulic ram 67 (see Figure 9). By reducing the effective length of ram 67, the front of the machine is pulled up towards plate 41. This can force the machine up onto the rear roller 5, thereby lifting the milling or grinding drum 6 up out of the ground. Similarly, reversing this operation will tilt the machine in the opposite direction, eventually forcing it up onto the front roller 4. Changing the effective lengths of hydraulic rams 45 and 48 will cause plate 40 to roll back and forth relative to plate 41. Figure 9 shows the operation of the integrated drive and governor system which includes two external hydraulic pumps 49 and 50. The power for the pumps 49 and 50 is supplied by the engine 51 of the multi-purpose vehicle or tractor 62. The power for hydraulic motors 17 and 18 (which are used to turn the front and rear drive rollers 4 and 5) is derived from the hydraulic power generated by pump 49 via a flow divider valve 52. The flow divider valve 52 operates to split the single hydraulic input into a double output, the two parts of which have equal volume of hydraulic oil flow. The output of pump 49 is fed to the drive rollers 4 and 5 via three flow control valves 53, 54 and 55 interposed between the flow divider valve 52 and the hydraulic pump 49. The hydraulic pump 49 can also be used to power a second apparatus (not shown) connected to one of the outputs of a flow divider valve 56 interposed between flow control valves 53 and 54. The flow control valves 53, 54 and 55 operate to govern the hydraulic power supplied to the motors 17 and 18 and hence the speed of the motors 17 and 18. Operation of the first control valve 53 is in turn controlled by the positioning sensor 36 located on the slider of the slider crank mechanism 14. When a build-up of material or a blast causes the slider mechanism 14 to operate, the sensor 36 sends a signal to the solenoid of the flow control valve 53, thus reducing the power supplied to the hydraulic motors 17 and 18. The next flow control valve 54 is used to prevent the engine 51 of the multi-purpose vehicle or tractor 62 from becoming over-loaded. This valve 54 is operatsd from a "revs, per minute" signal output from the engine 51. The third flow control valve 55 is operated by an external control device joystick 57 located in the multi-purpose vehicle or tractor 62. This allows the driver of the multi-purpose vehicle or tractor 62 to control the forward speed of the two drive rollers 4 and 5. The hydraulic pump 50 is used to provide power to the two hydraulic pumps 19 which drive the milling or grinding drum 6 of each drive unit. The supply of hydraulic oil to the motors 19 is fed through a flow divider valve 58 allowing the pump 50 to be connected to a second apparatus (not shown). Joystick 57 also controls the operation of the integrated steering and fixing system by sending signals to a solenoid box 59 which is used to control the hydraulic rams 44, 45, 47, 48 and 67. The solenoid box 59 has a second connection allowing control of a second integrated steering and fixing system, i.e. of a second de- mining apparatus being operated in parallel with the apparatus attached to the multi-purpose vehicle or tractor 62. The integrated steering and fixing system also includes an external solid state gyroscope 60 which is connected to an electronic signal interface box 61 which is used to operate the solenoid box 59. This allows automatic accurate control of the position of the land mine clearance apparatus in relation to the position of the multipurpose vehicle or tractor 62. Figure 10 shows the apparatus being used to clear vegetation and anti-personnel mines simultaneously. Two substantially identical drive units 63 and 64 are used, one mounted on the front of the multipurpose vehicle or tractor 62 and the other mounted on the rear thereof. The two drive units 63 and 64 are connected to the multipurpose vehicle or tractor 62 via the integrated steering and fixing systems 9 described above and the front and rear hydraulic connections on the multi-purpose vehicle or tractor 62 are used to operate the hydraulic rams 44, 45, 47, 48 and 67 of the integrated steering and fixing systems 9. The multi-purpose vehicle or tractor 62 can be elevated (as shown in Figure 10) and supported between the front and rear or first and second drive units 63 and 64 by operation of the hydraulic three-point linkage couplings located on the front and rear of the multi-purpose vehicle or tractor 62. The axial position of the multi-purpose vehicle or tractor 62 relative to the ground is controlled by a reference signal from the electronic signal interface box 61 mounted on the multi-purpose vehicle or tractor 62. The signal interface box processes the reference signal from the solid state gyroscope 60, which is also mounted on the multi-purpose vehicle or tractor 62. The front drive unit 63 can be angled with reference to the ground such that the milling or grinding drum 6 of the front drive unit 63 is positioned slightly above the ground and the rear drive roller 5 of the front drive unit 63 is the only part of the front drive unit 63 to be in contact with the ground. The milling or grinding drum 6 of the rear drive unit 64 is set so that it will penetrate into the ground to a predetermined level and the transit movement of both the front and rear drive units 63 and 64 is controlled by the integrated drive and governor system described above with reference to Figure 9. The integrated drive and governor system can be used to move both the front and rear drive units 63 and 64 forwardly, while carrying the multi-purpose vehicle or tractor 62 upwardly off the ground. The milling or grinding drum 6 of the front drive unit 63 effects cutting and clearing of the vegetation. Fitting of an external mulch blower device 65 can further process the vegetation. Thus, the mulched vegetation is removed by the blower device 65 after it has been processed by the milling or grinding drum 6 by blowing it upwardly and rearwardly out of the front drive unit 63. The forward-looking detector 10 of the front drive unit 63 is used to detect any buried objects larger than an anti-personnel mine. The information from the detector 10 and the ground speed radar 21 , 22 is processed by the on-board computer and global positioning system 26 which is mounted on the multi-purpose vehicle or tractor 62. When a large buried object is detected, the on-board computer sends a signal to the flow control valve 55, thus stopping the forward motion of the whole apparatus. The global positioning system then registers the position co-ordinates of the detected object. The computer also registers the size and shape of the object via information received from the detector 10 and the ground speed radar 21, 22. The operator of the multi-purpose vehicle or tractor 62 can then decide whether to carry on and grind up the detected object or to store the reference position of the detected object and leave it for later removal. The milling or grinding drum 6 of the rear drive unit 64 carries out the destruction of any anti-personnel mines. The counter-rotation of the drum 6, relative to the direction of travel of the apparatus, causes a layer of soil to be lifted by the drum 6, together with any object buried in this layer of soil. The depth of soil that the milling or grinding drum 6 is allowed to penetrate determines the depth of the layer of soil which is removed. The lifted soil and its contents are carried to the top of the drum 6 where the action of the rotation of the drum 6 and the tungsten carbide teeth 7 fixed to the drum 6 causes the soil and its contents to be pulverised, comminuted and, possibly, detonated as it passes through the gap between the drum 6 and the shear bar 8. The processed soil is then passed through the filtering device 16, thus conditioning the soil. The soil can then be seeded and fertilised using an externally mounted seeding and fertilising machine 66 mounted on the rear drive unit 64. The seed is then rolled in by the drive roller 5 of the rear drive unit 64 and the mulch blown up over the multi-purpose vehicle or tractor 62 by the mulch blower 65 is able to land on top of the seeded ground and provide a suitable germination cover. As will be apparent from the above detailed description, the front and rear drive units include a large number of common components, thereby minimising the number of replacement parts which have to be kept and facilitating regular maintenance and refurbishment operations.

Claims: Claims:- 1. A method for the clearance of anti-personnel mines, the method comprising:- a) providing a first ground-engaging drive unit which includes a milling or grinding drum, b) providing a second ground-engaging drive unit which includes a milling or grinding drum, c) connecting the first drive unit to the front of a vehicle and the second drive unit to the rear of the vehicle to form a mine clearance apparatus, and e) driving the mine clearance apparatus over the land to be cleared in such manner that the milling or grinding drum of the first drive unit grinds up the surface vegetation and the milling or grinding drum of the second drive unit grinds up a layer of soil and any antipersonnel mines contained therein. 2. Apparatus for use in the clearance of a minefield, the apparatus comprising first and second ground-engaging drive units each of which includes a milling or grinding drum, and each drive unit being provided with connector means such that the first drive unit can be connected to the front of a vehicle and the second drive unit can be connected to the rear of the vehicle to form an apparatus which can be driven over the land to be cleared in such manner that the milling or grinding drum of the first drive unit grinds up the surface vegetation and the milling or grinding drum of the second drive unit grinds up a layer of soil and any anti-personnel mines contained therein. 3. A method as claimed in Claim 1 or apparatus as claimed in Claim 2, in which the vehicle is connected to the first and second drive units in such manner that, when the apparatus is being driven over the land to be cleared of mines, the vehicle is supported clear of the ground by said first and second drive units. 4. A method as claimed in Claim 1 or apparatus as claimed in Claim 2, in which the first drive unit includes a detector for the detection of buried objects larger than anti-personnel mines. 5. A method as claimed in Claim 1 or apparatus as claimed in Claim 2, in which the first drive unit includes blockage prevention means to prevent clogging of the milling or grinding drum due to excessive vegetation, wet soil or other adverse conditions. 6. A method as claimed in Claim 1 or apparatus as claimed in Claim 2, in which the first and second drive units each include a blast damage reduction device to obviate damage due to blast energy from exploding anti-personnel mines. 7. A method as claimed in Claim 1 or apparatus as claimed in Claim 2, in which the second drive unit includes a soil filtering device for preparing the de-mined soil for agricultural seeding. 8. A method as claimed in Claim 1 or apparatus as claimed in Claim 2, in which an integrated drive and governor system is provided for moving the apparatus over the ground to be cleared under the power of the prime mover of the vehicle. 9. A method as claimed in Claim 1 or apparatus as claimed in Claim 2, in which an integrated steering and fixing system is provided for controlling movement of the apparatus over the ground to be cleared under the power of the prime mover of the vehicle. 10. A method as claimed in Claim 1 or apparatus as claimed in Claim 2, in which means are provided on the first drive unit for projecting ground-up vegetation upwardly and rearwardly so that it is applied on top of ground-up soil discharged from the second drive unit. 11. A drive unit which includes a milling or grinding drum, connector means for connection of the drive unit to the front or rear of a vehicle so that, when driven over the land to be cleared, the milling or grinding drum grinds up either the surface vegetation or a layer of soil and any anti-personnel mines contained therein, and a blast damage reduction device to obviate damage due to blast energy from exploding anti-personnel mines. 12. A drive unit as claimed in Claim 11 , which includes blockage prevention means to prevent clogging of the milling or grinding drum due to excessive vegetation, wet soil or other adverse conditions. 13. A drive unit as claimed in Claim 11 or Claim 12, which includes a detector for the detection of buried objects larger than antipersonnel mines. 14. A drive unit as claimed in Claim 11 or Claim 12, which includes a soil filtering device for preparing the de-mined soil for agricultural seeding.

Inventors: DIXON ROY, DIXON, ROY
Applicants: DIXON ROY, DIXON, ROY
Application year: 2001
Main classification: F41H11
IPC codes: A01B33, F41H11