EP0323941A2 - Method and apparatus for detecting and repeating at a distance the position of an impact on a target - Google Patents

Abstract

The invention relates to an apparatus intended for displaying on a screen the image of a target and the impacts (1) of the projectiles on the target in relation to particular sensors (3), (4), (4). The propagation speeds of the impact shock waves are measured in the actual material of the target. On the basis of these data, a computer determines the coordinates of the impact on the target and announces this vocally. Application: there is no need for any other device which will be at the target. A low cost price. <IMAGE>

Description

The present invention relates to a device intended to view remotely, on a screen, the image of a target used for firing and the successive impacts of projectiles having reached the target, and to translate phonetically in an audible manner. position of the impacts on the target.

Usually in a shooting range, each time you shoot at the target, to know the location of the impact, you must either move, or use a magnifying scope, or bring the target back to the shooter, or receive information from '' a person who examined the target.

All these methods, inconvenient, do not allow the shooter to focus on the sole practice of shooting to the best of his ability, being between two shots distracted by the impact tracking operation.

It is known for this, for example, from patent PCT-WO 86/03284 to associate several microphones with a target. The latter are capable of detecting in an acoustic chamber the sound signals generated by the impact shock on the target. However, such a known device has various major drawbacks.

First of all, it only works with high energy projectiles. Furthermore, it is absolutely prohibitive.

The present invention aims to avoid these drawbacks, while viewing on a screen, in the immediate vicinity of the shooter, the image of the target and the successive impacts of its shots on the target. This brings great comfort to the practice of this activity. Comfort can be further increased by an audible phonetic translation by the shooter of the positions of the impacts on the target.

A device according to the invention uses the propagation of sound in the material of the target itself to determine the differences in the distances of the impact at three fixed points on the target.

Knowledge of the differences d2 - d1 and d3 - d1 of the distances d1, d2, d3 of the impact at three fixed points on the target M1, M2, M3 indeed completely determines the position of the impact with respect to the target.

Indirect measurements of differences d2 - d1 and d3 - d1 are carried out by measuring the time elapsed since the arrival date of the noise of the impact of the projectile on the target having propagated in the material of the target, on the point M1, until the arrival of the noise of the impact having propagated under the same conditions on points M2 and M3.

The durations t2 and t3 thus measured corresponding respectively to points M2 and M3 make it possible to calculate d2 - d1 and d3 - d1, knowing the speed of sound in the material of the target.

A simple calculation then leads to the knowledge of the coordinates of the impact in a frame of reference (oxy) linked to the target.

According to a variant of the method, the time elapsed from the date of impact until the arrival of impact noise propagating in the target material is measured at two points M2, M3. These corresponding durations t2 and t3 lead to the knowledge of distances d2 and d3 of the impact at points M2 and M3, which is sufficient to determine the coordinates of the impact.

But this supposes that the impact is immediately detected by a sensor - accelerometer for example - to initialize the time counting. In general this process introduces an error on the calculation of d2 and d3. The use of three identical sensors eliminates this drawback.

According to another characteristic of the invention, the means used by the device are the target itself, the material of which must conduct sound without too much attenuation and time counting means.

The target, in cardboard for example, has at three of its points, three blind holes whose diameter is of the order of the precision expected in determining the coordinates of the impact.

On each of these holes is fixed a sensor sensitive to sound, microphone with electrets for example. The free end of the hole being closed by the microphone, a cavity is thus formed in the material of the target to serve as an acoustic impedance adapter between the material of the target and the microphone.

An electronic circuit is associated with each microphone so that, when the microphone is excited by the sound of the impact which has propagated in the target material up to the microphone passing through the cavity, the electrical circuit generates without delay a calibrated electrical signal suitable for triggering other circuits.

According to another characteristic of the invention, the device comprises two electronic timers.

Immediately after impact, the noise of the latter propagating into the target reaches the nearest microphone. The signal generated by the associated circuit is used to simultaneously trigger the two timers which then measure the time that elapses until the arrival of the impact noise propagating in the target on the other two microphones.

Each stopwatch being assigned to one of these two microphones by logic circuits, each of them stops counting the time when it receives the signal generated by the circuit associated with the microphone excited by the noise of the impact which has reached it. .

Thus, the contents of the two chronometers represent two durations which, multiplied by the value of the speed of sound in the material, of the distance at impact of the microphone associated with the chronometer and of the distance at impact of the microphone reached first by the noise of the impact and having initialized the time counting.

Knowing these two lengths and the position of the three microphones on the target in a frame linked to the target makes it possible to calculate the coordinates of the impact on the target in this frame.

According to another characteristic of the invention, the two durations measured by the chronometers after the impact of the projectile on the target are used in a calculation module which provides the coordinates of the impact on the target; the calculation module can be in a box either near the target or near the shooter.

According to another characteristic of the invention, a determined number of pairs of possible impact coordinates on the target are stored in an electronic memory. than. Each pair of durations provided by the chronometers makes it possible to search in a memory box for the coordinates corresponding to the impact.

According to another characteristic of the invention, the coordinates of the impact thus calculated or sought in memory, are entered by management circuits of a display screen which then displays a bright point representing the impact on the drawing of the target shown to scale on the screen. On the screen, the luminous points corresponding to the impacts preceding the last impact appear in a fixed manner. The last impact appearing on the screen in the form of a flashing light point.

The screen and the associated electronic circuits are contained in a box within immediate sight of the shooter

According to another characteristic of the invention, the various detection, measurement, calculation and management circuits are assembled in two boxes, one located at the foot of the target, the other near the shooter. The data transmission between the two boxes being carried out either by conductors or by radio.

According to another characteristic of the invention, the display screen is a flat screen with light-emitting diodes or with liquid crystals, but it can be produced by a cathode ray tube.

Of course, it would not go beyond the scope of the invention to use only two microphones fixed on the target; the two associated timers would then be triggered by a signal from an impact detector and efforts would be made to obtain, for good accuracy, the simultaneity of the impact and of the signal generated by the impact detector.

The durations measured by the two counters would then lead to knowing the distances of each of the microphones at impact, which is sufficient to determine the position of the impact on the target.

Finally, a single power supply battery can power the two boxes and the electro circuits nics in the case of a cable connection between the two boxes, two batteries being necessary in the case of a radio link, one battery per box.

It would not go beyond the scope of the invention to fix the microphones on the target material without leaving, at the place of the microphones, a hole in the target, the hole having only an adapter role. impedance.

• Figure 1 représente le synoptique du fonctionnement élec­trique du dispositif, schéma bloc de toutes les fonctions et indication des signaux et informations échangées.
• Figure 2 représente une cible avec dans un repère oxy les positions des microphones et d'un impact; les distan­ces des microphones d1, d2, d3 à l'impact y figurent.
• Figure 3 donne le détail de la fixation d'un microphone à électret sur la cible et de la cavité.
• Figure 4 situe les éléments constitutifs du système com­plet.
• Figure 5 et 6 sont des vues en coupe illustrant la struc­ture des capteurs dans un cas particulier.

The appended drawing, given by way of nonlimiting example makes it possible to better understand the characteristics of the invention and the advantages which it is capable of providing.

• Figure 1 shows the block diagram of the electrical operation of the device, block diagram of all the functions and indication of the signals and information exchanged.
• Figure 2 shows a target with in an oxy mark the positions of the microphones and of an impact; the distances of microphones d1, d2, d3 at impact are included.
• Figure 3 shows the detail of the attachment of an electret microphone to the target and the cavity.
• Figure 4 locates the components of the complete system.
• Figure 5 and 6 are sectional views illustrating the structure of the sensors in a particular case.

The electrical diagram illustrated in FIG. 1 includes a microphone 4 associated with the amplification and shaping circuit 5. The sensitivity and bandwidth of the set are adjusted to react only to the only impact noise propagating in the target material, to the exclusion of all other noises.

An impact detector 3 which, in this example, is an assembly identical to system 4 and 5, generating a signal 7 for triggering electronic timers 8.

The circuit 5 generates an electrical signal 11 which, applied to the stopwatch 8, determines the end of the time counting.

A calculation module 16 operating on the basis of a microprocessor receives the values 10 of the contents of the timers and calculates the coordinates of the impact. In another variant, a memory 24 contains a determined number of pairs of impact coordinates. Each couple of coordinates located in a memory box whose address is directly related to the content of the chronometers corresponding to the impact, this relationship being established by a prior calculation.

The supply of electrical energy can be done from an electric battery, or from a storage battery or from a power supply operating on the mains, located in the housing 15, by conductors of the cable 9 also supplying the housing 14.

The operation is as follows:
The shooter activates his weapon, firearm, gas, arrow, the projectile 6 reaching the target 1 generates in the material of the target an impulse noise which propagates in all the target at the speed of sound in the material of the target.

The noise begins by reaching the nearest microphone 3 and its associated circuit generates an electrical signal 7 (fig. 1).

The signal 7 is applied to the two timers 8, triggering their operation. At the same time, the two timers 8 are assigned to the other two microphones 4 (Fig. 1)

When the microphones 4 (FIG. 1) in turn receive the noise of the impact which propagates in the target, their respective circuits 5 each generate an electrical signal 11 which applied to the associated timer 8 ends its counting.

The two chronometers 8 thus contain the values of two durations t2 and t3 corresponding to the course of the distances d2-d1 and d3-d1 (FIG. 2) by the noise of the impact in the material of the target 1.

The values t2 and t3 available on the outputs of the timers 8 (signals 10) are integrated by the calculation module 16 which provides on its outputs the values x1 and y1 of the coordinates of the impact calculated from the values t2, t3, of the value of the speed of sound in the target material and the coordinates of the attachment points of the microphones.

In a variant, the couple (t2, t3) is used to generate an address of the memory box containing the pair (x1, y1) in memory 24.

A flat screen with liquid crystals or light-emitting diodes is managed by circuits 17 which receive the values of the coordinates of the successive impacts generating on the screen a bright point representing the impact.

These circuits can, in addition, generate various information displayed on the screen such as the impact number, the corresponding number of points, the total number of points achieved.

The screen shows the drawing of the target to scale.

The circuits 17 can transmit information to speech synthesis circuits 25 which generate vocables informing the shooter by phonic transducers 26 of the results of his successive shots for example by announcing after a shot the corresponding number of points and the situation of impact in polar coordinates.

Target 1 consists of a cardboard panel, square or rectangular; it is pierced with three holes 12 at locations 3 and 4. On one of its faces, these holes closed by gluing a patch 27. On the other face, an elastomer cap 20 contains an electret microphone 22 and is fixed to the target using an adhesive 13, at the location of the hole 12, providing a cavity 21, the electrical wires connecting with the microphone 23 come out of the cap 20.

Thanks to the adhesive, the cap is removable and can be installed on a new target. Each target has the blind holes and at the location of the holes, the adhesive protected by a patch. To use the target, remove the pellets and attach the caps to the adhesive. The six wires of the three microphones 22 arrive in a single cable in a box 14 which contains the circuits 5 and the electric supply battery.

The circuits 8 to 26 are distributed in the two boxes 14 and 15 and the connection between the two boxes for the transmission of the data is ensured by a cable with several conductors 9. This cable can, for example, carry the signals 7 and 11 in the case where the housing 14 does not contains only circuits 5.

The values of the coordinates of the impact 2 (x1, y1) are introduced into the screen management circuit 17 which generates the appearance of a luminous point on the screen, occupying on the screen, at l scale, the same position as impact 2 on target 1.

The last impact is represented on the screen by a flashing light point, the previous impacts being represented by light points without flashing.

At the same time, the circuit 17 generates useful information for the shooter, in alphanumeric form on the screen, such as the number of points corresponding to each shot, the total of the points, the number of each shot for example.

An improvement allows a speech synthesis circuit 25, receiving data from circuit 17 to supply the shooter via the transducer 26 with audible information on the position of the impact of his shot on the target, for example: "7 to 8 pm".

According to a very simplified use of the device, a single set -microphone 4 associated circuit 5- is used on the target under the same previous conditions of use.

It follows from the above that the invention, based on the transmission of acoustic waves within the target material itself, is based on the following observation:
At the moment of impact, from point 2, two wave trains arise within the target material,
- a wave propagating at around 2,800 m / s;
- a wave propagating at around 350 m / s.

It is by measuring the time intervals separating the reception of the waves successively at each of the sensors 3, 4, 4, that the position of the point of impact 2 is detected electronically.

This device has a considerable advantage over all known systems. It does not require any special device associated with the target. A simple card (target) is enough, associated with the three sensors which are fixed to it by an ordinary adhesive. This results in a particularly cost price low.

A major innovation according to the invention is constituted by the voice announcement of the position of the impact. This voice announcement is transmitted directly to the earphones worn by the shooter.

The x, y coordinates of the impact are "captured" by a circuit specialized in speech synthesis which generates terms such as: "an eight to 10 o'clock".

This allows the shooter to know if he is shooting without having to take his eyes off the target.

This device has been successfully tested in target shooting by blind people.

It is the most original part of the system.

Another very important advantage of the device: it can localize the impacts of all the bullets fired by all the weapons because its principle does not involve a greater or lesser energy of the bullet, nor a supersonic speed (shock wave).

With regard to the practical realization of the sensors, the following technology can be adopted.

In Fig. 5, a sensor 28 has been shown diagrammatically glued to the back of the target 1, so as to be sensitive only to the wave which propagates there at the speed of approximately 2,800 m / s. This sensor 28 comprises a casing 29 of plastic material, inside which is placed a piezoelectric patch 30. The latter is connected by wires 31 to the electronics of the system.

In Fig. 6, there is shown a sensor 32 sensitive to the wave which propagates in the target 1 at the speed of approximately 350 m / s. Here, we glue to the back of the target 1, a plastic case 33 which contains a filling of elastomeric foam 34 in which there is a microphone 35, for example of the electret type. The latter is connected to the electronics by wires 36.

Claims (19)

1. Method for determining the position of the impact (2) on a shooting target (1) by measuring the acoustic waves from sensors, characterized in that the sensors (3), (4) each measure the propagation of waves within the target material (1) to emit electrical signals then processed by an electronic assembly. 2. Device for implementing the method according to claim 1 and for indirectly determining the position of the impact of a projectile on a firing target and for transmitting this information remotely to be viewed, characterized in that it includes the following elements:
- a sensor (3) sensitive to the impact (2) of the projectile (6) on the target (1) delivering an electrical signal (7) at each impact, this signal defining the origin of the counting of time which coincides with the date of its appearance.
- Two sensors (4) sensitive to sound fixed on the target (1) at two fixed points - the two sensors are identical - each associated with an electronic circuit (5) adjusted to deliver an electrical signal (11) only when the sensor ( 4) is ecited by the noise of the impact (2) which has propagated in the material of the target (1) from the impact (2) to it.
- Two electronic chronometers (8), each chronometer associated with a sensor (4) is triggered by the signal (7) and measures the time which elapses from its triggering until the arrival of impact noise (2 ) - being propadans in the material of the target - on the sensor (4) associated with it, the end of the counting being obtained by applying to the chronometer (8) the electrical signal (11) The two durations (10) thus measured by the two chronometers (8) after each impact on the target, in association with the knowledge of the speed of sound in the target material (1) and the position of the three sensors (3) and (4 ° on the target determine the position of the impact (2) on the target (1) completely.
- A target - flat sheet made of sound conducting material - and therefore impact noise - on which are fixed the sensors (3) and (4) in a removable manner and impervious to external noise.
A data transmission system (9) from a box (14) located at the foot of the target (1) to a box (15) located in the immediate vicinity of the shooter.
- A calculation circuit (16) which calculates from the values of the durations (10) the coordinates (x1, y1) of the impact (2).
- A display screen (18) of the target image (1) and of the impacts (2) managed by an electronic circuit (17) receiving the values of the coordinates (x1, y1) to generate the light points representing the impacts (2).
- An electric generator (19) supplying all of the electronic circuits. 3. Device according to claim 2 characterized in that the sound sensitive sensors (4) consist of microphones (22) housed in a cap (20) fixing on the target in a removable manner. 4. Device according to claim 2 characterized in that the target (1) is made of sound conducting material which may be cardboard, and comprises at the location of attachment of the sensors (4) and (3) a blind hole (12 ), fixing the microphone (22) and its cap (20) at the location of the hole (12) thus creating a cavity (21) in the target (1) containing air and playing the role of adapter acoustic impedance between the target material (1) and the microphone (22) the impact noise (2) propagating in the target material (1) then in the cavity (21) before exciting the microphone (22). 5. Device according to any one of claims 2 and 4 characterized in that the target (1) does not have a hole at the location of attachment of the sensors (3) and (4), the impact noise is propagating from impact - in the target material - to the microphone (22) fixed on the target material (1) and by means of an adhesive material, or simply pressed on the target by a system mechanical, directly excites the microphone, target material. 6. Device according to any one of claims 4 and 5, characterized in that the target (1) has an adhesive (13) on its surface used for fixing the cap (20) and the microphone (22) on the target (1) in a removable and sealed manner in order to be able to change the target, the adhesive being protected by a patch when the target (1) is not used for shooting and which can be easily removed to uncover the adhesive. 7. Device according to claim 2 characterized in that the sensor (3) of impact detection is constituted by an accelerometer fixed on the target (1). 8. Device according to claim 2 characterized in that the impact detector (3) consists of a microphone (22) associated with a circuit (5), the microphone (22) being fixed by means of a cap (20), on the target (1) coincident with a blind hole (12) made on the target (1), the cap (20) and the microphone (22) closing the free orifice of the hole (12) a cavity (21) in the target carton (1) at this location, the impact sound (2) on the target (1) propagating in the target carton, then in the cavity (21) to energize the microphone (22) which causes the emission of an electrical signal (11) by the circuit (5). 9. Device according to claim 8 characterized in that the microphone (22) closest to the impact (2), therefore receiving, first, the impact noise (2) propagating in the target (1) , serves as an impact detection sensor and the signal emitted by its associated circuit fixes the time counting origin. 10. Device according to claim 2 characterized in that the display screen (18) is either a cathode ray tube or a flat screen with light emitting diodes or liquid crystal comprising the module 17 for managing the screen. 11. Device according to any one of claims 2 and 8 characterized in that the screen (18) is incorporated in a box (15) used to house any number of electronic circuits of the device, which can be distributed between the box ( 15) and a box (14) located at the foot of the target (1), connecting it to the microphones phones (22), the electrical connections between the boxes (14) and (15) being carried out by conductors (9), the power supply battery (19) being indifferently in one or the other box. 12. Device according to claim 9 characterized in that the transmission of data between the boxes (14) and (15) is carried out by radio, the box (14) then containing a transmitter, an electric supply battery and comprises a transmitting antenna, the box (15) containing the radio receiver, an electric supply battery and includes a receiving antenna. 13. Device according to claim 2 characterized in that it comprises an electronic memory (24) containing a determined number of pairs (x1, y1) of possible impact coordinates on the target (1), a number compatible with the definition and the capacity of the screen (18), the search in memory for a pair of coordinates (x1, y1) corresponding to an impact (2) having just occurred on the target (1) being made directly from the contents ( 10) chronometers (8). 14. Device according to claim 9 characterized in that the successive impacts on the target (1) are displayed in the form of light points on the screen (18), the last impact being displayed by a flashing light point, the position of the impacts on the screen being identical, to the nearest scale, to the position of the impacts on the target. 15. Device according to claim 3 characterized in that the microphones (22) are microphones with electrets. 16. Device according to any one of claims 2 and 7 characterized in that in the case where the shooter limits his exercise to reaching the target without being concerned with the positions of the impacts, a target is used equipped with a single microphone (22 ) and its associated circuit (5) operating as an impact detector, the circuit (5) delivering an electrical signal when the noise of the impact propagating in the cardboard of the target then in the cavity 21, reaches the microphone ( 22), this signal being used to trigger a signal perceptible by the shooter or for other purposes such as for example the triggering of a chronometer in its function of impact detector (3) and of origin of time counting of the device object of the invention. 17. Device according to any one of claims 2 and 8 characterized in that the target (1) has no hole at the location of the microphone (22), the noise of the impact propagating in the material of the target reaching the microphone without the intermediary of the impedance adapter cavity. 18. Device according to claim 2 characterized in that the target is a flat sheet of cardboard. 19. Device according to claim 2 characterized in that circuits (25), of speech synthesis, receiving the data from the module (17) and from the module (16) generate words by the transducer (26), audible by the shooter, translating phonetically the result of the last shot on the target (1) by giving the value of the points corresponding to the impact (2) on the target (1) and the position of the impact in polar coordinates.

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