GB2321882A

GB2321882A - Mine Detector

Info

Publication number: GB2321882A
Application number: GB9801992A
Authority: GB
Inventors: Thomas Muller; Frank-Lutz Dittman
Original assignee: Diehl GmbH and Co
Current assignee: Diehl Verwaltungs Stiftung
Priority date: 1997-02-04
Filing date: 1998-02-02
Publication date: 1998-08-12
Anticipated expiration: 2018-02-02
Also published as: DE19704080A1; DE19704080C2; GB2321882B; FR2759173A1; GB9801992D0

Abstract

A mine detector 10 is described which has a cross-country miniature vehicle, which has a number of mine-detecting needles 18 on a needle-head 16. A pressure-measuring sensor 20 is assigned to each mine-detecting needle 18, these needles preferably being arranged at intervals from one another side by side in a row. The pressure-measuring sensors 20 are interconnected with an electronic device 22 which is provided for controlling the mine-detecting needles 18 as well as for processing and evaluating the signals recorded. The electronic device 22 is preferably operatively connected with a central evaluating station 24, which is provided for controlling the miniature vehicle 12 and for evaluating the signals of the electronic device 22.

Description

1 2321882 MINE DETECTOR In the past few years, great ef forts have been

made in the f ield of sensor-based, automated seeking of antipersonnel mines (AP mines). In this connection, multiaxis metal detectors, geo-radar systems and olfactory sensors based on microsystem technology are for instance used in order to track down mines buried in the ground. Certain types of mine can very probably be detected by some of these known methods, but the required detection rate of >99.9% for the whole operating spectrum of AP mines can only be achieved with multi-mode sensor systems, in which the different types of sensor are combined. Such multi-mode systems have however until now not been ready f or production. This results f rom the great number of 1.5 different types of construction and different operational principles of mines as well as from the fact that AP mines are small in size and have no or almost no metal component. Moreover, as a rule, the ground in which AP mines are buried has an extremely complex radar 20backscatter behaviour so that geo-radar systems have only a limited use in this respect and place great demands on the capabilities of the signal processing being used. Apart from the inadequate detection rate of <99.9% of the known sensor-based mine-detecting methods, the high expenditure for the development and production of these sensor systems and for the associated signal processing proves to be a significant disadvantage in respect. of their practical use. For this reason, even today mines are still very frequently sought with the mine-detecting 2 needle which has been in use f or more than 50 years. In this respect, an engineer inserts a needle, usually made of non-magnetic steel, at intervals of 2 to 3 cm, and at an angle of approx. 450, into the ground lying before him and thus checks whether the needle encounters solid resistance. Based on the depth of a resistance detected in this way, the pressure distribution per unit of time and the distribution as regards area, said engineer can arrive at objects buried in the ground, such as AP mines or the like. With careful use it is possible with this simple method using a mine-detecting needle to detect all known mines with a detection rate of almost 100%. This does however assume that use of the mine- detect ng needle is fundamentally possible based on the nature of the ground. The personnel engaged in seeking mines by means of a mine- detecting needle are subject - as is quite obvious to great mental and physical stress. In addition, there is the risk that the personnel searching for mines will become careless when no mines are found for a long time. Another disadvantage which cannot be disregarded lies in the great amount of time needed for carrying out this method of mine- detection by means of mine-detecting needles.

The invention is based on the objective of producing a mine detector which does not have the disadvantages and which can achieve the required detection rate of at least 99.9% by relatively simple means.

above 3 In order to achieve this objective, according to the present invention there Is provided a mine detector, characterised by a cross-country miniature vehicle, which has a number of mine-detecting needles on a needle-head, a pressure-measuring sensor being assigned to each minedetecting needle and the pressure-measuring sensors being interconnected with an electronic device which is provided for controlling the mine-detecting needles and for processing and evaluating the signals recorded. Preferred designs and developments of the mine detector according to the invention are characterised in the sub-claims.

The mine detector according to the invention makes use of the principle of the mine-detecting needle, the search f or mines being automated by the use of a minedetecting robot f itted with a pressure-measuring sensory mechanism. The behaviour and procedural method of mineseeking personnel is reproduced by a suitable construction of the pressure-measuring sensory mechanism.

The cross-country miniature vehicle of the mine detector according to the invention, i.e. the minedetecting robot, consists of a robust vehicle cabin of preferably modular construction, which can easily be repaired as the need arises, on which the pressuremeasuring sensory mechanism is mounted together with the electronics for controlling the mine-detecting needles and for processing and evaluating the signals recorded. The 4 miniature vehicle can be remote- controlled and monitored from a safe distance, for instance by an engineer. This remote-control can be effected by radio or by means of wire. Said engineer can have at his disposal a central evaluating station in the form of a control computer. This control computer can for instance be the size of a laptop.

The measuring sensory mechanism has independently controllable mine-detecting needles which are arranged in a row side by side. The interval between the minedetecting needles can for example be 20 mm.

First of all, a contour-profiling or elevation profiling of the subsoil can be carried out by the pressure-measuring sensory mechanism before positioning the mine-detecting needles. Proceeding f rom the contourprofile determined in this way, the mine- detecting needles are then separately introduced into the ground to a predetermined depth. This depth can for example by 10 cm. By suitable control, it is ensured that the pressure required to trigger the AP mines is not reached or exceeded. Should the mentioned pressure reach a predetermined threshold value, which is less than the triggering pressure of AP mines, then the advance of the corresponding mine-detecting needle is immediately interrupted.

Apart from the pressure-measuring sensory mechanism, in the f ront part of the miniature vehicle a device is usefully provided for blowing out sand and small stones. Likewise a stripping device can be provided for cleaning the mine-detecting needles. A video camera can be mounted on the miniature vehicle so that the engineer handling the mine detector can visually assess the ground conditions or else visually assess a site to be searched. In order to be able to prepare a map of the terrain being searched by means of the mine detector according to the invention, it is expedient if the mine detector according to the invention is equipped with a global positioning system (GPS) for determining its actual position. It is preferable to use a OWS here, as a result of which the precision of the position indication is correspondingly increased. The position of the mine detector according to the invention can for instance also be determined by radio direction finding of the mine detector as is known per se. The determined positions of the mine detector can be transmitted to the central evaluating station and filed there. Thus a precise marking of the cleared areas can be ensured.

Objects located in the ground are detected with the 25mine detector according to the invention by analysing the pressure profiles recorded by means of the pressuremeasuring sensory mechanism and dependent on the depth of penetration of the mine-detecting needles. For this 6 purpose, it is f irst of all decided, by classification of the pressure distribution per unit of time of a measuring needle, whether the measuring needle has encountered a solid or a movable object such as a small stone, or whether the measuring needle has only come up against the resistance typical of the actual subsoil. By evaluating the position and magnitude of the two-dimensional distribution of the classification results in respect of the subsoil lying ahead of the miniature vehicle of the mine detector according to the invention, mines lying on the ground or buried in the ground can then be detected.

The mine detector according to the invention has the advantage that, by evaluating the ground pressure profiles, a very reliable detection is ensured in respect of a wide variety of types of mine, this very reliable detection being accompanied by a relatively simple design of the mine detector according to the invention. Another advantages lies in that the personnel involved in the mine search are outside the danger area during operation of the mine detector according to the invention, so that any risk to mine-detecting personnel is eliminated.

The invention will be described further, by way of example, with reference to the accompanying diagrammatic drawings in which:- FIGURE 1 shows a working example of the mine detector in 7 combination with an associated central evaluating station, and FIGURE 2 shows a block circuit diagram in respect of the 5 mine detector according to FIGURE 1.

FIGURE 1 shows a construction of the mine detector 10 with a crosscountry miniature vehicle 12 which has a needlehead 16, with a number of mine-detecting needles 18, on an arm 14 of the sensory mechanism. In FIGURE 1, only one of these mine- detecting needles 18 can be seen, the rest of the mine-detecting needles 18 are hidden by this one minedetecting needle 18. In the needle-head 16, a pressuremeasuring sensor 20 is assigned to each mine-detecting needle 18. The pressure-measuring sensors 20 are interconnected with an electronic device 22 which is provided for controlling the mine-detecting needles 18 and for processing and evaluating the signals recorded, as explained below in conjunction with FIGURE 2. The electronic device 22 is operatively connected with a central evaluating station 24. This operative connection is indicated by the arrow 26 drawn with a dot-dash line. Here it can be a question of a wire connection or a wireless radio connection.

The miniature vehicle 12, taking the form of track laying vehicle, is equipped with a video camera 28. In the ground marked with a reference number 30, there is a 8 mine 32 which is being sought by means of the mine detector 10.

FIGURE 2 shows in a block diagram representation the pressure-or def lection-measuring sensory mechanism 34 and a metal detector 36 which are interconnected with the electronic device 22, this being indicated by the two arrows 38. A one-dimensional signal reprocessing stage is marked with the reference number 40, and a classification of the time-signal pattern stage is marked with a reference number 42. Reference number 44 marks a twodimensional signal preprocessing stage and reference number 46 marks a stage for classification of the twodimensional distributions for, for example, the comparison with so-called mine fingerprints. A transmitter of the electronic device 22 is marked with the reference number 48, this transmitter serving for the transmission of data. A transmitting antenna 50 is connected with the transmitter 48. The circuit block stage 46 indicating the classification of the two-dimensional distributions is or can be connected with a mine-data bank 52, which is indicated by the double arrow 54.

The arrow 56 between the electronic device 22 and the pressure- or deflection-measuring sensory mechanism 34 illustrates the adapting of the sensing interval or measuring interval and the control of the advancing speed of the respective mine-detecting needle 18 (see FIGURE 1).

9 The video camera 28, also represented in FIGURE 1, is connected with the electronic device 22 or with the transmitter 48 of the electronic device 22, as indicated in FIGURE 2 by the arrow 58.

In FIGURE 2, the central evaluating station Is illustrated by block 24. The central evaluating station 24 has a data-transmission receiver 60, with which a receiving antenna 62 is connected, a device for visualising the results 64, which is connected with a data store 70, as well as a control unit 72.

The cross-country miniature vehicle 12 has a robust, preferably modular construction. Due to the modular construction, any necessary repairs are facilitated, separate components can be easily and quickly replaced. The dimensions of the miniature vehicle can for example be in the order of magnitude of 60 cm wide, 120 cm long and 50 cm. high. Of course the miniature vehicle 12 can also have different dimensions.

The mine-detecting needles 18 are arranged in a row side by side and spaced at intervals from one another. The width of search of the mine vehicle 12 is determined by the number of mine-detecting needles 18 and by the distance between adjacent mine-detecting needles 18. By varying the inserted position of the mine-detecting needles 18, it is possible to reduce as required the interval between mine-detecting needles and thus to correspondingly increase the resolution. Such a variation of the inserted position of the mine-detecting needles 18 is usefully effected depending on the results of the signal evaluation. Thus, if it is suspected that a mine 32 has been detected, the resolution is correspondingly increased so as to verify the result.

The mine-detecting needles are preferably inserted into the ground 30 at a specific angle of inclination in relation to the vertical. This angle can f or example be 450. It can be varied. The depth of penetration of the mine-detecting needles 18 into the ground 30 is limited to a specific maximum depth. The mine-detecting needles 18 are controlled independently of one another, in each case by a variable drive. In this connection, it can be a question of a hydraulic device. The speed and rate or amount of advance of the mine-detecting needles 18 is controlled by the signal processing alorithms of the electronic device 22. During the advance, the pressure exerted on the respective mine-detecting needle 18 is measured by means of the associated pressure-measuring sensor 20. Should the pressure measured exceed a predetermined threshold value, which is less than the triggering pressure of AP mines 32, then the advance of the corresponding mine-detecting needle 18 is immediately interrupted. During the advance, the pressure distribution per unit of time of the respective mine- 11 detecting needle 18 is recorded. The pressure distribution per unit of time - as well as the deflection behaviour--- is recorded in respect of each separate mine detecting needle 18, independently of the other mine detecting needles 18, by means of the pressure- or deflection-measuring sensor mechanism 34.

After measurement of a "baselinen, the miniature vehicle 12 is moved a specific distance in direction of travel, after which the mine-detecting needles 18 are then again inserted into the ground 30.

A blowing-out unit 74 provided on the needle-head 18 (see FIGURE 1) serves to remove sand and small stones.

A stripping unit 76 is provided for cleaning the mine-detecting needles 18.

With the deflection sensor assigned to the respective mine-detecting needle 18, it can be a question of a DMS sensor, which, on encountering a solid object or sliding down a smooth surface, generates corresponding signals. Said signals of the DMS are separately recorded and evaluated in respect of each mine-detecting needle.

For tracing down antitank mines (AT mines) in particular, it is preferable if the mine detector 10 has at least one metal detector. A visual assessment of the 12 terrain lying ahead of the miniature vehicle 12 is possible by means of the video camera 28. A onedimensional laser scanner can also be used to determine the terrain lying ahead of the miniature vehicle 12, i.e. 5 the contour-profile of the ground 30.

As can be seen in FIGURE 2, a multi-stage process is used f or evaluating the sensor data, i.e. the signals of the pressure- or deflectionmeasuring sensory mechanism 34 and/or the signals of the metal detector 36. First of all, the variation per unit of time of the sensor signals corresponding with the actual pressure or actual deflection during penetration of the mine-detecting needles 18 into the ground 30 is subjected to a sample or pattern detecting process and classified. This is indicated in FIGURE 2 by blocks 40 and 42. On a basis of the classification results, in the next stage, which is indicated in FIGURE 2 by blocks 44 and 46, methods of image processing are used in order to evaluate the two- dimensional distribution of the classified pressure- and deflection variations is effected by a comparison with the "fingerprints" of AP mines 32 deposited in the mine-data bank 52. For this purpose, methods from neuronal networks, Fuzzy Logic and Neuro-Fuzzy-algorithms are used for example, so that human expert knowledge on the use of mine-detecting needles can be modelled and consulted for the evaluation.

13 The mine-detecting needles 18 are controlled, as regards the position and as regards the advance of the mine-detecting needles 18, depending on the results on evaluation of the sensor signals. As has already been mentioned, on detecting 91suspicious', objects, the resolution is then increased in direction of travel of the miniature vehicle 12 and at right angles to it.

An assessment of the subsoil according to type and composition can be carried out by an analysis of the sensor signals at points where there are no mines. The advancing speed of the mine- detecting needles 18 is controlled on a basis of these results. In this way, an optimisation of the advancing speed is possible, as a result of which the time needed for the mine search is minimised.

The evaluation of the sensor signals as regards pressure and deflection also allows an assessment of the terrain or ground 30 lying ahead of the miniature vehicle 12 so that objects lying on the ground's surface can be recognised and the depth of penetration of the minedetecting needles 18 into the ground 30 can be precisely determined.

In order to prepare a map of the cleared area of ground, it is preferable to precisely determine the position of the miniature vehicle 12. This can be 14 determined by means of DGPS or possibly also by radio direction finding of the miniature vehicle 12. The measured positions of the miniature vehicle 12 are transmitted to the central evaluating station 24 and are filed there. The central evaluating station 24 is operated by mine-seeking personnel who stay at a safe distance from the miniature vehicle 12. Thus the results of the signal processing of the electronic device 22 are transmitted by means of a cable or preferably by radio to the central evaluating station 24 and are visualised there. In combination with the images of the video camera 28, the mine-seeking personnel operating the central evaluating station 24 can observe the progress of the miniature vehicle 24 and can intervene in a corrective capacity if the need arises.

With the central evaluating station 24, it is possible to simultaneously monitor and control a number of miniature vehicles 12.

The area of ground to be cleared can be predetermined by a programming of the route of the miniature vehicle 12 by way of the central evaluating station 24. Moreover, a self-testing function of the miniature vehicle 12 can be activated by the central evaluating station 24. The advantage of this is that the diagnosis and repair of damaged components of the miniature vehicle 12 are significantly simplified.

The data transmitted by the electronic device 22 of the miniature vehicle 12 can be f iled by means of a data store of the central evaluating station 24, 1. e. of the evaluating computer.

16

Claims

1. A mine detector, characterised by a cross-country miniature vehicle, which has a number of mine-detecting needles on a needle-head, a pressuremeasuring sensor being assigned to each mine-detecting needle and the pressure-measuring sensors being interconnected with an electronic device which is provided for controlling the mine-detecting needles and for processing the evaluating the signals recorded.

2. A mine detector as claimed in Claim 1, characterised in that the miniature vehicle can be remotecontrolled.

3. A mine detector as claimed in Claim 1, characterised in that the minedetecting needles are arranged in a row side by side at intervals from one another on the needlehead.

4. A mine detector as claimed in Claim 3, characterised in that the minedetecting needles are arranged at a specific angle of inclination in relation to the vertical.

5. A mine detector as claimed in Claim 4, characterised in that a deflector sensor is assigned to each minedetecting needle.

6. A mine detector as claimed in any one of the 17 preceding claims, characterised in that a cleaning device is assigned to the mine-detecting needles.

7. A mine detector as claimed in any one of the preceding claims, characterised in that a blowing-out device, for removing sand and small stones, is provided on the miniature vehicle.

8. A mine detector as claimed in any one of the preceding claims, characterised in that a video camera is mounted on the miniature vehicle.

g. A mine detector as claimed in any one of the preceding claims, characterised in that a tool arm is provided on the miniature vehicle.

10. A mine detector as claimed in any one of the preceding claims, characterised in that a surveying device is provided for preparing maps of the region.

11. A mine detector as claimed in Claim 10, characterised in that the surveying device has a global positioning system.

12. A mine detector as claimed in any one of the preceding claims, characterised in that at least one metal detector is provided on the miniature vehicle.

18 14. A mine detector as claimed in any one of the preceding claims, characterised in that a central evaluating station is provided, which is "operatively connected with the electronic device of the miniature 5 vehicle.

15. A mine detector substantially as hereinbefore described with reference to the accompanying diagrammatic drawings.

ill Amendments to the clakns have been filed as foikms 1. A mine detector, comprising a cross-country miniature vehicle, a number of mine-detecting needles on a needle-head, a pressure-measuring sensor being assigned to each mine- detecting needle and the pressure-measuring sensors being interconnected with an electronic device which is provided for controlling the mine- detecting needles and for processing and evaluating the signals 10 recorded.

2. A mine detector as claimed in Claim 1, characterised in that the miniature vehicle can be remote-controlled.

6. A mine detector as claimed in any one of the -W preceding claims, characterised in that a cleaning device is assigned to the mine-detecting needles.

9. A mine detector as claimed in any one of the preceding claims, characterised in that a tool arm is provided on the miniature vehicle.

-M 14. A mine detector as claimed in any one of the preceding claims, characterised in that a central evaluating station is provided, which is operatively connected with the electronic device of the miniature 5 vehicle.