GB2418476A

GB2418476A - Defensive land mine

Info

Publication number: GB2418476A
Application number: GB9806746A
Authority: GB
Inventors: Uwe Aulenbacher; Randolf Barg; Axel Kaspari; Dietmar Sieg; Rolf John
Original assignee: Tzn Forschung & Entwicklung; Rheinmetall Industrie AG; Rheinmetall W&M GmbH
Current assignee: TZN FORSCHUNGS- UND ENTWICKLUNGSZENTRUM UNTERLÜSS; Rheinmetall W&M GmbH
Priority date: 1997-03-25
Filing date: 1998-03-12
Publication date: 2006-03-29
Anticipated expiration: 2018-03-12
Also published as: GB9806746D0; FR2874252A1; DE19712371A1; GB9725616D0; SE9800792L; GB2418476B; SE527322C2

Abstract

A surface defence mine has a housing (2), at least one dischargeable sub-ammunition body, a multi-mode sensor system and an electronic evaluation system (15) combined with the said multi-mode sensor system. To ensure better release and target contact performance at greater distances a number of acoustic sensors (8) and a number of radar sensors (9) are provided around the outside of the mine housing (2). A target classification is effected both by means of the acoustic sensor and by means of the radar sensors (8,9) and is evaluated by the electronic evaluation system (15). The acoustic sensors (8) effect an approximate target bearing angle measurement, which is then used in order to activate a particular radar sensor (9) situated on the periphery of the mine housing (2) of which the directional characteristic embraces the detected target (19) concerned. The electronic evaluation system (15) then determines, from the corresponding signals of the said radar sensor (9), any curved course (10) taken by the target (19). A seismic sensor (18) may also be provided.

Description

24 1 8476

TITLE

Defensive Land Mine This invention relates to a land mine for defence purposes with a housing, at least one dischargeable sub-ammunition body, a multi-mode sensor system and an electronic evaluation system combined with the said multi-mode sensor system.

Areas are secured and monitored using such land mines, also called surface defence mines, provided with a sensor system for the classification of targets, particularly motorised, and also for determining the course taken by the moving target present at the time. From the data the electronic evaluation system then determines the firing signals for the sub-ammunition body to be launched at the target. The targets are usually wheeled or tracked vehicles, so that the target classification is frequently carried out by means of acoustic and seismic or vibration sensors.

The known mines suffer from the disadvantage of a relatively high rate of false triggering, as acoustic or seismic sensors are a very 2() inaccurate means of determining the transit path of the relevant target.

Further known surface defence mines have a radar system for determining the transit path, in most cases with only one radar antenna pvotably mounted on the mine housing Among the disadvantages of these known mines is the fact that accurate ciass'ficaton of the target Is rarely possible, because specially armoured weapon systems are often equipped with camouflage devices making it impossible for the target to be accurately classified by radar and IR radiation. Furthermore, production and assembly costs in the case of pivotable radar antennas are comparatively high. Finally, the antenna has to be mounted at a considerable height to enable targets still at a distance of 300 m, for example, to be detected.

One object of this invention is to provide a surface defence mine which even at relatively large distances (such as 300 m) will ensure a more satisfactory activation and hit rate than is obtainable with comparable mines of a known type.

According to this invention there is provided a surface defence mine having a housing, at least one dischargeable sub-ammunition body, a multimode sensor system and an electronic evaluation system combined with said multi-mode serisor system, wherein (a) the multi-mode sensor system includes an array of at least three acoustic sensors and a radar system; (b) the acoustic sensors of the array being arranged around the mine housing whereby on the reception of acoustic signals from a possible target the electronic system determines from the propagation time differences between the signals received from each acoustic sensor, a corresponding bearing angle of the target, (c) the radar system comprising radar antennas which are positioned around the mine housing and connected with the electronic evaluation system In such a way that after the bearing angle has been determined by the acoustic sensor array that particular radar antenna can be activated which is within said bearing angle, and (d) the electronic evaluation system having at least one micro processor which from the acoustic data measured and the radar measurement values effects a target classification and/or a target speed measurement, estimates the target speed from the change undergone by the bearing angle over a period of time and utilises these values in order to derive signals for firing the mine.

The principle on which the invention is mainly based is that of providing a number of acoustic sensors and also a number of radar sensors (radar antennas) around the exterior of the mine housing. In this process the targets are classified both by means of the acoustic sensors and by means of the radar sensors and evaluated by the electronic evaluation device. The acoustic sensors also serve to determine the approximate target or bearing angle, which is then used to activate that particular radar sensor on the periphery of the mine housing of which the directional characteristic includes the relevant target. The electronic 2() evaluation device then determines, from the corresponding signals of the said radar sensor, the course taken by a curved path of a target.

A sensor system of this kind ensures, in the first place, greater probability of classifying a possible target correctly than is possible with known systems, because the classification Is effected by two different physical methods In the second place the homing accuracy of the mine is considerably greater than that of mines only provided with acoustic and/or seismic sensors, because the radar sensor is a highly accurate means of determining a curved path of the target. The activation of the radar sensors, moreover, only involves moderate expenditure, because no rotating antenna parts are required.

A hybrid system of this kind, moreover, comprising acoustic sensors and radar sensors, offers the additional advantage that in the event of failure of the radar system the mine nevertheless remains q usable, because the approximate course taken by the target can also be determined by means of the acoustic sensors alone.

In order, in particular, to improve the accuracy of the target classification still further, it has been found advantageous for at least one seismic sensor to be integrated into the mine in addition to the acoustic sensor and radar sensors.

In one version of the invention, in order to reduce current consumption, the electronic evaluation unit comprises a time interrupt circuit connected with the acoustic sensor array and/or the seismic sensor, in such a way that the radar system will not be activated until acoustic and/or seismic signals relevant to the target are received.

In a further particularly advantageous version of the invention the sensors and the electronic evaluation system are affixed to a cylindrical housing component of the mine. This enables the installation height of the sensor system to be kept very low. Furthermore, the complete sensor systems, including any electronic evaluation device, can be s manufactured as a pre-assembled unit.

The acoustic sensors are preferably mounted on pivotable arm- shaped retaining parts which during or after the mine-laying operation can be pivoted out from recesses provided in the cylindrical housing on component. This enables the mines to be stored without occupying more than a moderate amount of space. It also ensures that acoustic sensors will not be destroyed during storage or transport.

Finally, it has been found advantageous for the mines according to the invention to be so designed that a number of such mines can be combined to form a minefield capable of being activated, the individual mines being combinable with one another through wired or wireless communication devices.

Further features and advantages of this invention will be described with reference to examples and by reference to the drawings, wherein: Figure 1 shows a diagram, in perspective, of a surface defence mine with acoustic sensors turned about hinges into the mine housing; figure 2 shows a cross section along the line 11-ll through the mine shown in Figure 1, with acoustic sensors pivoted out of the housing; and figure 3 shows a block diagram of an electronic evaluation system connected to a number of sensors.

Referring to the drawings, Figure 1 shows a surface defence mine 1 according to this invention. The mine 1 comprises a cylindrical housing hi, 2 and a firing device 3, only Indicated schematically, for a subammunition body which is not shown in the drawing. The mine 1 rests on the ground through three extensible legs 4.

The mine housing 2 Is made up of a base part 6 and an upper housing part 7, three acoustic sensors 8 and radar sensors 9 are distributed around the periphery of the housing part 7. Each of the acoustic sensors 8 are positioned on a first end 10 of a corresponding arm-shaped retaining part 11. The second end 12 of each retaining part 11 is pivotably mounted on the upper housing part 7, in such a way that the acoustic sensors 8 can be pivoted out of corresponding recesses in the upper housing part 7 from a stowed position into an operating position, see Figure 2.

The acoustic sensors 8 may comprise microphones and the radar sensors 9 used may comprise strip antennas connected with a software- controlled multiplex network 14, such as a Butler network, see Figure 3, Of an electronic evaluation system 15. To enable the electronic evaluation system to be accommodated in a moderate space inside the mine housing 2, the electronic system can be positioned, for instance, either on the inside 16 of the upper housing part 7, as indicated in Figure 2, omnside a suitable recess (not illustrated) of the said upper part 7.

2() As shown in broken lines in Figure 1, the base 17 of the mine housing 2 is also fitted with a seismic sensor 18, typically a geophone device Both the acoustic sensors 8 and the seismic sensor 18 are likewise connected with the electronic evaluation system 15.

Figure 1 also shows an armoured target 19 to be attacked moving 2S over a curve path 20.

Figure 3 shows the block diagram of an example of the electronic evaluation system 15. The electronic evaluation system mainly comprises a real-tme computer system with a micro-computer 21 which is connected through analog/digital converters 22, 23 and a threshold value circuit 24, with the acoustic sensors 8 and the seismic sensor 18 and also, through the micro-computer 21, is connected by an analog/digital converter 25, a radar transmitter 26 and the multiplex network 14 with the radar sensors 9. The multiplex network 14 in this system is activated by the microcomputer 21, which is likewise connected by a corresponding line 27 with the network 14.

The method of operation of the electronic evaluation system is now described.

When the mines 1 are being laid the acoustic sensors 8 are automatically pivoted outwards as in Figure 2. If a tracked vehicle 19 IS then moves past the mine as in Figure 1, the corresponding airborne sound waves or ground vibration waves are received by the sensors 8,9, and conveyed to the circuit 24 which, for example, effects a threshold value comparison. Insofar as the measuring signals exceed the preselected threshold value, corresponding signals reach the micro 2() computer 21, which determines both the target classification charactenstcs from the acoustic and seismic signals and in each case estimates the speed of the possible target 19 from the course taken over a period of time by the signal values measured. In addition, the micro computer 21, on the basis of the propagation time differences between 2, the measuring signals of the individual acoustic sensor 8, determines the approximate bearing angle of the possible target 19. The micro- computer 21, via the multiplex network 14, then activates the particular radar sensor 9 which has the directional characteristic towards the tracked vehicle 19.

Using the radar system, which is preferably a Doppler radar, both the distance of the target 19 from the mine 1 and the radial speed of the target are determined in addition to the exact bearing angle at which the mine 1 sees the target 19. Finally, by using the radar sensors 9 and the electronic evaluation system 15 connected to them, a target classification is carried out.

From the different values for the target classification the electronic evaluation system 15 makes an appropriate estimate. Furthermore, the curved transit path 10 of the target 19 is determined from the bearing angles, the speed values and the distance of the target. These values are then utilised in order to generate detonation signals causing the sub ammunition projectile of the mine 1 to be fired and also resulting in the detonation of this projectile in the target area.

This invention may be modified and is not limited to the example described above. The seismic sensors, for instance, can also be laid 2() possibly manually and separately from the mine 1 whereby an operative inserts the sensors in the ground 5, for example using ground spikes, and connects them to the mine In question by means of suitable cables.

Furthermore, the radar system with eight strip antennas 9, as described, can be replaced by a system with an omnidirectional antenna

Claims

ClAIMS 1. surface defence mine having a housing, at least one

dischargeable sub- ammunition body, a multi-mode sensor system and an electronic evaluation system combined with said multi-mode sensor system, wherein (a) the multi-mode sensor system includes an array of at least three acoustic sensors and a radar system; (b) the acoustic sensors of the array being arranged around the mine housing whereby on the reception of acoustic signals from a possible target the electronic system determines from the propagation bme differences between the signals received from each acoustic sensor, a corresponding bearing angle of the target; (c) the radar system comprising radar antennas which are positioned around the mine housing and connected with the electronic evaluation system in such a way that after the bearing angle has been determined by the acoustic sensor array that particular radar antenna can be activated which is within said bearing angle, and (d) the electronic evaluation system having at least one micro processor which from the acoustic data measured and the radar measurement values effects a target classification and/or a target speed measurement, estimates the target speed from the change undergone by the bearing angle over a period of time and utlises these values in order to derive signals for firing the mine.
2. Surface defence mine In accordance with Claim 1, wherein the multimode sensor system in addition to the acoustic sensor array and the radar system has an additional target classification and/or target speed measurement device with at least one seismic sensor connected to the electronic evaluation system.
3. Surface defence mine in accordance with Claim 1 or 2, wherein the electronic evaluation system includes a threshold evaluating circuit connected with the acoustic sensor array and/or the seismic sensor whereby the radar system can be activated on the reception of acoustic and/or seismic signals relevant to the target.
4. Surface defence mine in accordance with any one of Claims 1 to 3, wherein the sensors and the electronic evaluation system are secured to a cylindrical housing component of the mine, which said component is produced as a pre-assembled unit.
5. Surface defence mine in accordance with Claim 4, wherein the acoustic sensors are mounted on pivotable arm retaining means which during or after laying of the mine are pvotable outwards from recesses provided in the cylindrical housing component.
6. Surface defence mine In accordance with any one of Claims 1 to 5, ll wherein a number of such mines are used in combination to form a mine field, the individual mines being interconnectable through wired or wireless communication devices.
7. Surface defence mine in accordance with any one of Claims 1 to 6, wherein the radar antennas positioned around the mine housing are strip antennas connected through a multiplex network with the electronic evaluation system.
8. Surface defence mine in accordance with any one of Claims 1 to 7, wherein the radar system is a Doppler radar.
9. Surface defence land mine constructed and arranged to function as described herein and exemplified with reference to the drawings.