GB2144523A - Sensor detonation arrangement - Google Patents

Abstract

When obtaining a detonation signal 3 from the output signals 12 of several detectors 14, 17, preferably associated with different spectral regions it is ensured that combining the signals 12 does not prevent the triggering of the detonation signal 3 upon failure of a single signal 12 and even leads to greater target detection probability. Each digitised target signature (27) derived from a detector output signal 12 yields a detonation criterion 29 and an associated target probability criterion 30 derived from a spectral or other information comparison with predetermined criteria, and the detonation criteria 29 weighted with their target probability criteria 30 are additively combined in order to trigger the detonation signal 3 only when the summation reaches a threshold value. In order to take into account the target detection uncertainties at great target distances 21, a distance-dependent evaluation quantity 37, the value of which increases with the target approach, can be obtained by distance measuring equipment 38 from at least one of the detector output signals 12. <IMAGE>

Description

SPECIFICATION A method of generating or triggering a detonation signal and a detonation arrangement This invention relates to a method of generating or triggering a detonation signal as well as to a detonation arrangement more especially but not exclusively for supplying a detonation signal for the service (combat) charge of a sub-ammunition body.

German Auslegeschrift No. 26 08 067 shows a method and detonation arrangement in which each of the sub-munitions (subammunition) bodies ejectable from a fired carrier body is designed to be able to attack a target detected during a decelerated fall into the target region or, in the event of a target not yet being detected, to serve, as a mine after landing in the target region. To provide these different attack facilities, a multiplicity of detectors for supplying detonation criteria is provided, which detectors are linked together by means of logic circuits in order to supply the actual detonation signal in the event of a target being sighted or detected.

It tends to be disadvantageous that in the generation of the detonation signal from the logic linkage (gating) of differently obtained (detected) detonation criteria, in the case of a logic OR-linkage on the one hand, no real increase in the probability of target detection occurs (despite the multiplicity of detectors) because each occurring detonation criterion independently triggers the detonation signal even when different false target reports are present in the OR-input channels; whilst on the other hand in the event of a logic ANDlinkage of several detonation criteria, no target attack at all is possible (i.e. no generation of the detonation signal is possible) if only just one of the criteria linked together fails.

According to the present invention there is provided a method of triggering or generating a detonation signal using target detection means arranged to detect at least two different information criteria relating to a target, comprising: (a) obtaining a first detector output signal from a first information criterion relating to the target, and obtaining a second detector output signal from a second information criterion relating to the target; (b) processing the first and second detector output signals to generate or trigger the detonation signal by:: (1) analysing the first detedtor output signal and issuing a first provisional detonation signal if the first detector output signal carries the required information criterion; (2) obtaining a first target probability criterion associated with the first detector output signal; (3) analysing the second detector output signal and issuing a second provisional detonation signal if the second detector output signal carries the required information criterion; (4) obtaining a second target probability criterion associated with the second detector output signal; (5) combining a first provisional detonation signal if issued with its associated target probability criterion and combining the second provisional detonation signal if issued with its associated target probability criterion; and (6) combining the first provisional detonation signal if issued and its associated target probability criterion with the second provisional detonation signal if issued and its associated target probability criterion to provide a resultant value and thereby triggering or generating the detonation signal provided the resultatnt value reaches a threshold level, or triggering or generating the detonation signal if the first or second provisional detonation signal only and associated target probability criterion reaches a threshold value.

Further according to the present invention there is provided a sensor detonation arrangement for carrying of the method according to the immediately preceding paragraph.

Still further according to the present invention there is provided a method of generating or triggering a detonation signal on target detection from detonation criteria which are supplied by several detectors and which are obtained in separate information processing channels and are then linked or combined together, characterised in that from detector output signals, which are preferably associated with different spectra of the electromagnetic radiation from the target region, a target probability criterion is obtained for the respective detonation criterion and the detonation signal is only issued when a combination of the detonation criteria, respectively weighted with their target probability criteria, has reached a threshold value.

Still further according to the present invention there is provided a sensor detonation arrangement having several detectors and a multi-channel information processing mechanism for supplying detonation criteria to a data link for the issuance of a detonation signal on detection of a target, the arrangement being prefereably for a sub-munitions body, in which several detectors, preferably designed for different spectra of electromagnetic radiation from the target object, are connected to a respective information processing channel for supplying the detonation criterion and a target probability criterion associated with the detonation criterion to the data link, and in which, in use, the detonation criteria weighted with their target probability criteria are, linked and are passed to a threshold value stage for the issuance of the detonation signal.

The present invention realises that to increase combat success if may indeed be basically correct to improve the probability of target detection by linking or combining several separately obtained detonation criteria; but such linking or combining must not lead to a blocking of the detonation signal by failure of even just one of all the detonation criteria taken into account. In this respect, more especially, the different detonation criteria may be advantageously, in the interests of reliable target identification, obtained from pieces of information associated with different spectral regions of electromagnetic energy, such as for example by means of one detector which responds to heat radiation and of a further detector which responds to very high frequency wave radiation.Of course, should a target be shrouded in thick mist an infra-red detector would not supply a detonation criterion. However, this must not block the emission of a detonation signal if at least one further detector, for example a magnetic-field detector or a very high frequency detector, has with very great probability detected a target that is to be attacked.

The present invention may provide a method and a sensor detonation arrangement in which the probability of target detection is increased by using different detectors or detection means simultaneously yet without the failure of one detector channel preventing, in the event of reliable target detection, the triggering of the detonation signal.

Thus, in each detector channel not only a detonation criterion may be obtained, but also, preferably simultaneously, a piece of information about the target probability (i.e. a degree of certainty that the target detected represents a target that is to be attacked).

Then for each detector channel the detonation criterion can be weighted, with its target probability criterion, preferably by a muultiplication process, (by multiplicative linkage); according to which a combination (arithmetic or algebraical linkage) of these resulting pieces of information triggers the detonation signal when the summation result has at least reached a predetermined response threshold.

This threshold can be achieved if several detonation criteria with only moderate target probabilities yield as a whole the adequate sum; but also indeed this threshold can be achieved if one detonation criterion is not pesent at all or is present only with very low target probability (for example on account of failure of the radiation spectrum associated with this detector), but another detonation criterion with very high target probability is present (for example on account of very typical target identification factors for the radiation spectrum being picked up by another detector).

Additionally, in the multiplication evaluation of the detonation criterion with probability weightings it can be taken into account that in detection of a target from a very great height (on account of the fact that there is then still very great uncertainty of attack success with a sub-munitions combat charge; and also on account of the fact that there is general uncertainty in target classification from great heights) the detonation signal is to be triggered only if target probabilities are present which are well above average. For this, it is advantageous for a system-related evaluation by combination (multiplication or multiplicative linkage), before the combination (summation) of the weighted signals is effected, with a piece of information which is dependent upon target range.This additional height-dependent evaluation is (after coverage of a certain descent distance from ejection of the sub-munitions body from its carrier body) for example in a time-dependent manner taken up or directly set to 100%. This is because upon close proximity to the target plane the detonation of the effective charge must no longer be held back or affected by such a height dependent evaluation (in the hope of finding a still higher target probability); because even on a low target probability the detonation of the effective charge, shortly before the end of the descent time, is acceptable in combat tactical respects.

Thus, with comparatively simple signal-processing means, for different detector output signals, a high probability of effective attack of defined targets is achievable. More especially current sensors may be used which in themselves - without these signal processing measures - are not at all suitable for target detection from the great initial height and would usually result in false reports in the initial phase of the descent which would previously have caused the combat charge to detonate prematurely.

An embodiment of a method of generating or triggering a detonation signal and a sensor detonation arrangement in accordance with the present invention, will now be described, by way of example only, with reference to the much simplified schematic drawing which is a single Figure showing a block diagram of the sensor detonation arrangement.

Referring to the Figure, the sensor (sensorised) detonation arrangement 1 is incorporated into a sub-munitions body 2 (also designated as a small bomb or active scatter munition) and serves to issue a detontion signal 3, on detection of a target 5 in the detection direction 6, for detonating a combat charge 4.

The detonation arrangement 1 is built up from several, (preferably as shown from two) parallel-working, information processing channels or routes 7, 8, which are brought together in a data link 9, which link, on target detection, supplies the detonation signal 3. Also, the data link 9 (which is preferably realised as a programmed processor) includes a time con trol mechanism 10 for issuance of control program signals 11 in a time-dependent manner and by means of which mechanism 10 digital data processing both on and after digitisation of detector output signals 12' is controlled, similarly as the temporal course of arming and auxiliary functions in connection with detonation readiness of the sub-munitions body 2.The time control mechanism 10 is activated out an initial state by a piece of initiation information 13; the inormation 1 3 is transmitted to the sub-munitions body 2 upon the, or in consequence of the, ejection of the mechanism 10 from its carrier body (not taken into account in the drawing) and can at the same time serve for activation of an energy supply for the detonation arrangement.

The two channels 7, 8 are designed for, relative to electromagnetic energy picked up from the target 5, different radiation spectra.

Thus, in a preferred embodiment, channel 7 works on an infra-red detector 14 (shown as an optoelectronic transducer 1 5 behind an optical lens system 16) and the other channel 8 works on an extra high frequency detector 17, (shown as an antenna 1 8 at the focal point of a concave mirror reflector 19).

The infra-red detector 1 4 is, preferably, a passive sensor system, which thus picks up heat radiation 20 emanating from the target 5 itself or emanating from another source and reflected by the target. The high frequencywave detector 1 7 is, preferably, an active radar system more especially when the detector is intended simultaneously to be utilised for ascertaining the target distance 21. Alternatively, however, a passive system (radiometer principle) is also sufficient which picks up only the high-frequency radiation 22, reflected at the target 5, from the outer area - or which picks up the radiation shadow/silhouette - of the target relative to the background.

In each information processing channel 7, 8 the original detector output signal 1 2 is amplified and filtered in a band-pass preamplifier 23 or in an integrated microwave circuit 24, for low-pass, interference elimination and high-pass, drift suppression. The so cleanedup detector output signal 12' (which is still an analogue signal) is then digitised by means of an analogue/digital converter 25. Following this, the detonation signal 3 is obtained from digital information processing, which processing can be carried out inside a single processor 26.The data width (bit count) of the processor 26 is to be selected in accordance with the information extent (content) and the time available during the descent path of the gub-munitions body for the identification of the target object 5, taking into account the store organisation and decentralised data processing in peripheral computer circuits. Basically, taking into account relevant realistic or practical factors, processor 26 is sufficient as a 1 6-bit processor.

In each channel 7, 8 from the digitised signature 27 of signal 12' by means of a feature or criterion analyser (Merkmalsanalysator) 28 a detonation criterion 29 as well as a target probability criterion 30 associated with this is obtained and issued to the data link 9.

The detonation criterion 29 can be interpreted as a provisional detonation signal; which signal, however, only actually leads to the issuance of a detonation signal 3 when its probability value is very high - or when, simultaneously, from another of the channels 7, 8 likewise a detonation criterion 29 with at least adequate probability value is supplied. The probability value is high when specific detection or identification criteria for the target 5 can be reliably discovered. In order to obtain, besides the mere detonation criterion 29, also its associated target probability criterion 30, each feature analyser 28 has a comparator 31 which is fed on the one hand directly, and on the other hand by way of an adaptive threshold stage 32 with the signature obtained from the detector output signal 12'.

The adaptive threshold stage 32 adjusts itself automatically, in accordance with the base signal level (background noise) emanating from the surroundings of the target 5.

Therefore, the stage 32 adjusts initially, during a certain initial timespan of descent of the sensor detonation arrangement 1 and after occurrence of the initiation information 13, to an initial value, and in the course of further descent, it adjusts continuously by reason of the change in the statistical (the statistics of the) terrain information. As compared with continuously adjusting threshold information also the target 5 itself will yield different information through a defined change in the short-time amplitude statistics of its signature 27; this leads to the controlling-through (switching-through) of the comparator 31.

On occurrence of detonation criterion 29, the comparator 31 supplies a signal to a feature/criterion extractor 33 (Merkmalsextraktor) which is fed directly with the signature 27. In the extractor 33 the temporal behaviour of the signature 27 (in other words the amplitude/time course thereof) is analysed in itself and with regard to the threshold value resulting in accordance with reducing target distance 21, more especially with respect to the frequency and length exceeding the threshold value. It is advantageous to undertake in the course of digitisation in the converters 25 by appropriate distance-dependent control of a scanning rate, a standardisation of the signature 27, as described in German Patent No. 31 33 570.In this way the data processing expenditure is reduced advantageously on comparison with predetermined or pre-programmed target identification criteria inside the feature extractor 33. The target probability criterion 30 can be obtained simply from an evaluation of the signal to noise ratio in the detector output signal 12; or a pattern (sample) recognition classification is effected by a vectorial comparison; in this respect specific target properties are represented by vectors in a multi-dimensional vector space, and the length of the resulting vector of all the partial features (components) from the centre, or centre of gravity, of a specific target partial space represents a mathematical measure of the target probability of the temporally associated detonation criterion 29.In any event, each feature analyser 28 supplies (from the comparison with predetermined information about typical targets 5) besides the detonation criterion 29, a target probability criterion 30.

Each detonation criterion 29 can now be multiplicatively linked (multiplied) in a multiplier 34 with its target probability criterion 30 (value between 0% and 100% inclusive), in other words be weighted; then the signal processing results of the separate channels 7, 8 can then be linked (combined) without problems- namely without mutually blocking one another. Adder 35 is connected subsequent to the multipliers 34 to link together the weighted signals of the separate channels 7, 8. Only when the result of this algebraic (arithmetic) addition reaches or exceeds a value preset in a threshold value stage 36 is the probability sufficiently great that instantaneously a target 5, to be attacked by means of the charge 4, has been detected in the detection direction 6, which is why the detonation signal 3 can then be issued.

In the drawing it is taken into account that it can be advantageous to subject the already weighted detonation criteria 29 to an additional system evaluation weighting. This consists in the (multiplicative) consideration of a height-dependent evaluation quantity 37, which is obtained for example from target distance measuring equipment 38. Here, for the continuous determination of target distance 21, active reflection locating equipment or a position finder (transit time measurement) can be provided. It is less complex to ascertain the target distance 21 starting from an initial range (which begins with the occurrence of the initiation information 13) constantly with the descent approach of the submunitions body 2 into the target region; for example by evaluating the distance-dependent variation of the mean intensity of the radiation 20 or 22.Then, by means of the height evaluation quantities 37 thus supplied by the measuring equipment 38, on processing the detonation criteria 29 it can be taken into account that the information extraction in the channels 7, 8 begins on ejection from the carrier body (occurrence of the initiation information 13) and thus at a very great distance 21 above the target 5. In the case of great height the reliability of the detonation criteria 29 is necessarily less than in the case of reduced target distance 21. Therefore the weighting with the height evaluation quantity 37 ensures that in the case of fairly great target distance 21 the detonation signal 3 is only triggered when a fairly strong target probability criterion 30 is provided, in other words when instantaneously a target object 5 is detected with fairly great certainty.With a fairly short target distance 21, the probability that a detonation criterion 29 can actually be associated with a defined, and to be attacked, target 5 is greater; which is why towards smaller target distances weakening of the detontion criterion 29 weighted with the target probability can be a retrograde step, in other words the evaluation quantity 37 for the (multiplicative) signal processing can be raised.

In the described embodiment, the adaptive threshold stage 32 contains only the digitised signature 27. it supplies an output signal to comparator 31 if signature 27 experiences a typical modification so that detector 1 4 or 1 7 will not only recognize the landscape but also a target object. Threshold stage 32 is, therefore, provided with its own learning ability, i.e. it adapts to the landscape information, which differs from the recognition of a target object by specific criteria (such as the time behaviour of the amplitude fluctuations in detector output signal 12).The typical characteristic is that a statistical analysis of the amplitude and time behaviour of signal 1 2 is carried out in threshold stage 32 during the first few seconds of body 2 falling into the target area, and the result of this analysis is defined as a non-target; this analysis result will change on approaching the target area but only if there is a sudden and typical modification to the analysis result since such a modification is likely to be caused by the recognition of a target object (a tank, for example).

This modification is detected by comparator 31, which is supplied with the total information of the detected signature 27 (terrain information and target data) on the one hand, and the reference information from stage 32 which is determined by the momentary (adapted) short-term amplitude statistics typical for the terrain background and contained within signature 27, on the other hand.

The two input data to comparator 31 are in the form of digital values; it supplies the unmodified detonation criterion 29 if these values suddenly differ to a considerable extent. This can, therefore, be interpreted as the classical evaluation of a 'jump' in the useful /interference amplitude ratio; in fact, the statistical analysis of the amplitude/time behaviour of signature 27 (i.e. signal 12) provides much more valid criteria. The feature/ criterion extractor 33 is directly supplied with signature 27 on the one hand, and with the unmodified detonation criterion 29 on the other hand; both cases relate to information (not to simple trigger pulses).

The feature/criterion extractor 33 uses the comparison between the overall signature 27 and the target information differing from the terrain background and supplied by stage 32 to define a number of object criteria (such as the temperature distribution, dimensions, movement along the terrain) and compares this sum total of criteria, which can be interpreted vectorially, with a typical criterion of the target to be attacked. The greater the correspondence between the vector total and the anticipated typical criterion, the higher the value of the output target probability criterion 30 will be.

The detonation criterion 29 supplied by comprator 31 to the data link 9 could be in the form of a trigger pulse; in fact, it is the digital code data relating to the target object, as seen in comparison with the momentary (adapted) terrain background which was recognised.

The conventional signal/noise ratio of an input signal is only of secondary importance in this case; it will, indeed, be incorporated in terms of its amplitude into the short-term statistics of signature 27, but the latter is characterized more by its amplitude/time behaviour. The adaptive threshold 32 is essential (at least in the described embodiment) in order to take account of changes in the background radiation of the terrain when approaching the target level and to compare this with the sudden recognition of a target object.

The preset threshold value stage 36 serves to pevent the detonation signal 3 being given and the combat ammunition being detonated if the adder 35 has only arrived at a low value output, since this would suggest that a further target recognition with a higher success probability will be carried out when body 2 is closer to the target area, so that the combat ammunition must be reserved for such a later stage. The threshold value stage 36 must, therefore, be dimensioned to suit the tactical conditions during the manufacture of submunitions body 2.

The increase in effectiveness is produced by the fact that target probability criteria are obtained in various spectral bands from detector signals 1 2 and that these can be taken into account during the logic linking of the detector signals 1 2. If detectors 14/17 were to operate in the same spectral band, they would be influenced in the same way by the same landscape phenomena (fog clouds, expanses of water, etc.) or the same false targets (burning oil vats). The increase in effectiveness is, therefore, only present if the illusory targets are shown differently in detectors 14/17 - since detectors 14/17 operate in different spectral bands.

Claims (3)

1. A method of generating or triggering a detonation signal on target detection from detonation criteria which are supplied by several detectors and which are obtained in separate information processing channels and are then linked or combined together, characterised in that from detector output signals, which are preferably associated with different spectra of the electromagnetic radiation from the target region, a target probability criterion is obtained for the respective detonation criterion and the detonation signal is only issued when a combination of the detonation criteria, respectively weighted with their target probability criteria, has reached a threshold value.

2. A method as claimed in claim 1, in which each weighted detonation criterion experiences, prior to combination, additionally a system evaluation weighting.

3. combining the first provisional detonation signal with its associated target probability criterion to obtain a resultant value and generating or triggering the detonation signal once a threshold is reached for the resultant value.

3. A method as claimed in claim 1 or 2, in which the combination of the detonation criteria is an addition of the products from detonation criteria and target probability criteria.

4. A method as claimed in claim 2 or 3, in which in the system evaluation the instantaneous distance of a detector relative to the target is used.

5. A method as claimed in one of the preceding claims, in which the target probability criterion is related to the signal-noise ratio.

6. A method as claimed in any one of the preceding claims, in which the target probability criterion is related to the displacement of a vector, resulting from several target criteria, from the centre or centre of gravity of a partial region in multi-dimensional vector space.

7. A sensor detonation arrangement having several detectors and a multi-channel information processing mechanism for supplying detonation criteria to a data link for the issuance of a detonation signal on detection of a target, the arrangement being preferably for a sub-munitions body, in which several detectors, preferably designed for different spectra of electromagnetic radiation from the target object, are connected to a respective information processing channel for supplying the detonation criterion and target probability criterion associated with the detonation criterion to the data link and in which, in use, the detonation criteria weighted with their target probability criteria are linked and are passed to a threshold value stage for the issuance of the detonation signal.

8. A sensor detonation arrangement as claimed in claim 7, in which for the detonation criterion and target probability criterion of each channel a multiplier is provided and each multiplier is connected to an adder in front of the threshold value stage.

9. A sensor detonation arrangement as claimed in claim 7 or 8, in which provided in each channel is a feature analyser, a feature extractor of which issues a target probability criterion in accordance with the signal/noise ratio in the detector output signal and/or the temporal course thereof and/or deviations from predetermined target recognition criteria and/or the instantaneous target distance relative to the detonation criterion.

1 0. A sensor detonation arrangement as claimed in one of claims 7 to 9, in which the data link and the feature analysers are constituent parts of a digital processor, which has a time control mechanism for obtaining a height evaluation quantity and for further program controlled operations in the detonation arrangement and in the submunitions body where applicable.

11. A method of generating or triggering a detonation signal substantially as herein described with reference to the accompanying drawing.

1 2. A sensor detonation arrangement substantially as herein described with reference to the accompanying drawing.

1 3. A sub-munitions body including at least one sensor detonation arrangement as claimed in any one of claims 7 to 10, 1 2.

14. A method of triggering or generating a detonation signal using target detection means arranged to detect at least two different information criteria relating to a target, comprising: a). obtaining a first detector output signal from a first information criterion relating to the target, and obtaining a second detector output signal from a second information criterion relating to the target; b). processing the first and second detector output signals to generate or trigger the detonation signal by:: 1). analysing the first detector output signal and issuing a first provisional detonation signal if the first decector output signal carries the required information criterion; 2). obtaining a first target probability criterion associated with the first detector output signal; 3). analysing the second detector output signal and issuing a second provisional detonation signal if the second detector output signal carries the required information criterion; 4). obtaining a second target probability criterion associated with the second detector output signal;; 5). combining the first provisional detontation signal if issued with its associated target probability criterion and combining the second provisional detonation signal if issued with its associated target probability criterion, and 6). combining the first provisional detonation signal if issued and its associated target probability criterion with the second provisional detonation signal if issued and its associated target probability criterion to provide a resultant value and thereby triggering or generating the detonation signal provided the resultant value reaches a threshold level, or triggering or generating the detonation signal if the first or second provisional detonation signal only and associated target probability criterion reaches a threshold value.

1 5. Further according to the present invention there is provided a method of triggering or generating a detonation signal using target detection means arranged to detect information criteria relating to a target, comprising; a). obtaining a first detector output signal from a first information criterion relating to the target, b). processing the first detector output signal to generate or trigger the detonation signal by; 1). analysing the first detector output signal and issuing a first provisional detonation signal if the first detector output signal carries the required information criterion; ; 2). obtaining a first target probability criterion associated with the first detector output signal,