METHOD AND DEVICE FOR DETERMINING THE SHOT EFFECT

Description

Scope of the invention

[0001] The present invention relates to the field of shot analysis, particularly in the field of training, and relates to a device and a method for determining shot impact. State of the art

[0002] During live-fire training, particularly small arms training, it is essential to be able to reliably and in real time report on projectile firing, whether real or simulated. Such requirements impose certain characteristics on the analysis systems considered. These systems must have an accuracy comparable to that obtained in real-world situations, while being minimally intrusive, meaning they must require the minimum amount of additional equipment mounted on the weapon being used.

[0003] Among the methods for simulating impacts during training, there is laser illumination technology.

[0004] The principle is similar to that of "Laser Ball" where the aim is to simulate a rifle fight, with rifles without projectiles but equipped with a laser emitter that simulates the firing of ammunition.

[0005] Participants, both shooters and potential targets (infantry, vehicles), are equipped with a number of sensors (including smart sensors and photosensitive sensors that trigger an alarm whenever they are hit by a laser beam), lasers (for detection and firing simulation), and other functional devices (batteries, computing and communication units). All of these devices are distributed across the training equipment, whether on the head (on a helmet), attached to the participant's uniform in front and / or on the back, or mounted on the weapon(s).

[0006] These laser technologies for shooting training have multiple disadvantages: laser attenuation over long distances, inability to shoot through blurry obstacles (e.g. foliage), need to equip the target with enough photosensitive sensors, which can also be obscured by mud splashes, among other things.

[0007] However, the reliability and accuracy requirements for real-world scenarios must overcome several practical operational barriers such as the weight and bulk of additional onboard equipment, performance (accuracy and latency), kit autonomy, but also technological barriers which are mainly the accuracy of recorded and analyzed data, the reliability of image analysis, the minimum computing power onboard in the device, the throughput and consumption of the wireless link.

[0008] The following documents propose approaches to determining a point of impact of shots on a target: US 2021 / 3727738 A1; EP 2 456 009 A1; CN 112 969 139 A. However, these solutions do not offer sufficiently precise identification of the target hit.

[0009] There is therefore a need for an appropriate solution that allows us to overcome these limitations.

[0010] The present invention addresses this need. Summary of the invention

[0011] One aim of the present invention is to remedy the aforementioned drawbacks of known approaches, by proposing a method (and an associated device) which makes it possible to determine a point of impact on a target during a training shot.

[0012] Advantageously, the present invention offers a so-called hybrid solution based on the cross-analysis of radio and video information produced by three types of sensors.

[0013] The principle of the invention consists of a sequence of processes comprising: The detection of the discharge of a round from a weapon, by a module mounted on the weapon; The identification of participants (potential targets) as well as their angular positions in the frame of reference of the weapon that fired, by a localization means with limited precision; The detection of targets by an appropriate image processing module, from an image seen from the barrel of the weapon taken by an optical sensor; The performance of a precise ballistic calculation which takes into account the kinematics of the round (from a ballistic computer), the kinematics and distance of the target (perceived by the camera), as well as the kinematics of the weapon (as perceived by an inertial measurement unit mounted on the weapon); and The identification of the participant who crosses the ballistic trajectory of the round at the time of impact, as well as the determination of the part of the body (for an infantryman) or the area (for an object) that is hit.

[0014] Attrition data can then be transmitted to the target and the training monitoring system via a radio channel. This information allows for the simulation of a shot fired at a human or vehicle, the determination of attrition due to the ammunition's impact point, and the application of this attrition to the participant concerned, by warning them that they are hit or dead, disabling their weapon, etc.

[0015] To obtain the desired results, a device for determining the point of impact on a target during a training shot is proposed, as defined in the attached set of claims.

[0016] The present invention also addresses a weapon equipped with the device of the invention.

[0017] Another object of the invention is a method for determining the point of impact on a target during a training shot, as defined in claims 9 and 10.

[0018] The invention in another aspect covers a computer program product comprising non-transient code instructions for performing the steps of the process as claimed when said program is executed on a computer. Description of the figures

[0019] Various aspects and advantages of the invention will appear in support of the description of a preferred, but not limiting, embodiment of the invention, with reference to the figures below: There figure 1 illustrates the arrival of a plane wave at a pair of antennas. figure 2 This illustrates how to determine the position of an object using triangulation. figure 3 is a graph to illustrate the accuracy of a measurement of the angle of arrival of a wave. figure 4 This illustrates in 2D the determination of the angular position of targets within the frame of reference of a weapon. figure 5illustrates a 3D example of determining the angular position of targets according to one embodiment of the invention. figure 6 This illustrates an example of target detection and localization achieved through the implementation of the device of the invention. figure 7 illustrates a method for determining shot impact according to the invention. Detailed description of the invention

[0020] The invention makes it possible to determine the point of impact on a target, particularly during training fire with a small arms. To determine the impact produced by a shot, the method of the invention comprises several combined data processing steps that make it possible to identify a participant who has been hit by ammunition, and to determine the area of ​​impact of the shot on the participant (human or object).

[0021] The device of the invention thus has a combination of means to enable the determination of a shot impact, each means taken in isolation not enabling the production of the precision required for the field of application.

[0022] Existing localization methods do not have sufficient accuracy to reliably designate a target when used alone. Therefore, the present invention combines information from multiple radio and video data acquisition methods to obtain a precise result in determining the impact of a shot.

[0023] Different embodiments of the radio localization function can be implemented in order to carry out this data acquisition part of the device of the invention.

[0024] Thus, in one embodiment, a function can be implemented which allows the localization of shooters and targets in a global frame, and a function which allows a calculation of the position of the targets in the shooter's frame.

[0025] In the case of outdoor location, one implementation method may be the use of a GNSS system (“Global Navigation Satellite System” in English).

[0026] With a combination of multi-constellation satellite systems, such as for example the 'BeiDou', 'Galileo', 'GLONASS' and 'GPS' systems, and considering the ability to use differential correction streams (the 'GPS RTK' device - 'Real Time Kinematic' - allows real-time transmission of correction data from an observation base to mobile GPS units), it is possible to achieve sub-meter location accuracy.

[0027] However, this technology cannot be used inside buildings or in areas of interference where satellite signals are not available.

[0028] In one embodiment, a radio location technology or (RTLS) for "Real Time Locating System" in English may be implemented.

[0029] The state of the art in indoor radio localization allows for accuracy of less than one meter, or even around 10 centimeters under optimal conditions.

[0030] In one embodiment, the radio location technology can be an ultra-wide band or (UWB) technology, which is based on a time of flight or (ToF) method.

[0031] The time-of-flight (ToF) method allows the distance between two radio transceivers to be measured by multiplying the ToF of the signal by the speed of light. These times of flight can be calculated either from bidirectional communication between fixed anchors and modules to be geolocated, known as "Two Way Ranging" (TWR), or from unidirectional communication between fixed anchors and modules to be geolocated, known as "Time Difference of Arrival" (TDoA).

[0032] In one embodiment, the radio location technology may be an Angle Of Arrival (AOA) technology, in particular an Angle Of Arrival technology for Bluetooth 5.1.

[0033] The AOA method uses the phase difference of reception of a signal on an anchor network with multiple antennas, in order to calculate the angular position of the beacons relative to the anchors, and deduce the geographical position of the beacons by triangulation.

[0034] However, these solutions, used alone, would require the deployment of a substantial infrastructure. Indeed, "anchors" would need to be installed at regular intervals across the entire area, and their deployment would be complex: network and power connectivity, precise geolocation measurement, a clock synchronization system for TDoA techniques, and so on.

[0035] Furthermore, depending on the technology used, restrictions on the number of elements to be located and the refresh rate may apply.

[0036] Therefore, the use of radio location technology alone cannot guarantee the accuracy required for determining the impact of shots.

[0037] Another positioning technology is odometry.

[0038] Odometry is a technique for estimating the position of a moving object by iteratively observing that movement with "sensors".

[0039] Positioning by odometry can utilize different types of sensors.

[0040] In the case of a wheeled vehicle, observing the rotation of the wheels allows us to reconstruct the overall movement of the vehicle.

[0041] Inertial odometry uses a measurement unit to iteratively calculate the position of the moving object by integrating inertial data from sensors such as accelerometers, gyroscopes, magnetic compasses, and barometers. This data is generally combined using a filter (Kalman, Madgwick, complementary, etc.).

[0042] Visual odometry allows us to estimate the displacement of a mobile device equipped with a calibrated camera by iteratively calculating the camera's displacement between each successive image, using image analysis and projective geometry methods.

[0043] Other sensors can be used for odometry-based positioning.

[0044] All these methods calculate the position iteratively, and are subject to a greater or lesser degree of drift due to the limited precision of the calculations and the accumulation of measurement errors (such as measurement noise).

[0045] To make them more robust, it is possible to hybridize them: for example, using visual odometry and inertial odometry.

[0046] Another classic method for positioning trajectories within a global geographic coordinate system is the use of spatial anchors placed either at the beginning of the route (with initial positioning) or along its entire length (with recalibration to limit drift). These anchors, whose positions are known, can be gantries, visual markers in the case of visual odometry, etc.

[0047] In another embodiment of the invention, the localization means consist of a function enabling the direct localization of targets in the shooter's frame of reference.

[0048] As explained previously, AOA technologies are classically used to perform beacon geolocation relative to a wide network of antennas.

[0049] In the context of the invention, the inventors propose to use this AOA technology to meet the need to validate target alignment directly in the weapon's reference frame.

[0050] In one embodiment, AOA Bluetooth 5.1 technology is used to determine indoor positioning.

[0051] The angle of arrival (AOA) method consists of an exchange of data packets between a transmitting device called a beacon and a receiving device called a locator.

[0052] This latter device has several antennas that are separated by a known distance, as illustrated on the figure 1 (source: “Bluetooth Special Interest Group”) which shows the arrival of a plane wave (Radio Signal) on a pair of antennas (ANT1, ANT2) separated by a distance “d”.

[0053] The receiver has several antennas, generally distributed concentrically to be able to detect signals from the beacon in 360°.

[0054] A trigonometric calculation allows us to determine the angle where the beacon is located relative to a pair of 2 receiver antennas using the following formula: θ = arccos ψλ / 2 ∏ d with 'θ' the angle of arrival in radians allowing to locate where the beacon is in relation to the receiver; 'ψ' the phase difference between the waves received by the two antennas of the receiver; 'λ' the wavelength of the received signal, i.e. 0.125 m with the frequency of 2.4 GHz of Bluetooth; 'd' the distance between the 2 antennas.

[0055] The positioning system then uses a collection of locators (each with several antennas) to locate the beacons by triangulation, according to a known calculation illustrated on the figure 2 (source: "Texas Instrument forum") with two locators separated by a distance 'D'.

[0056] Thanks to the measurement accuracy of angle θ, it is possible to locate indoors with an accuracy of less than one meter.

[0057] It should be noted that measurement accuracy can be affected by the "bounce" or occultation of radio waves by metallic surfaces.

[0058] In another embodiment of the direct calculation of angular positions in the weapon's frame of reference, UWB technology using AOA is employed to determine indoor positioning. UWB (Ultra Wide Band) technology enables localization by angle of arrival detection.

[0059] The inventors determined that, in the case of Bluetooth, analysis of AOA technology shows that, in the simple case of two collinear antennas, the measurement accuracy of the angle θ is maximal (i.e., < 1°) along the axis perpendicular to the two antennas (Phi = 0). The diagram of the figure 3 (source: “Texas Instrument Designs: TIDA-01632”) illustrates this aspect.

[0060] Given that the area of ​​interest for the localization measurement is within a "small" angle, i.e., a few degrees in front of the weapon's barrel, the distribution of the measurement error (recorded on the curve of the figure 3 ) shows that the embodiment according to the AOA Bluetooth technology is particularly advantageous.

[0061] Furthermore, in the case of target alignment, it can be assumed that the space between the shooter and their target is free of obstacles, and thus the measurement accuracy is not affected by interference from metallic structures in the path. The range of a Bluetooth or BLE (Bluetooth Low Energy) signal must then be maximized (over 100 m).

[0062] There figure 4illustrates a 3D example of determining the angular position of targets according to an embodiment of the invention. In this simplified but non-limiting example, a shooter is equipped with a weapon that includes a radio target location means having two antennas (ANT1, ANT2), and three participants are potential targets (two humans and a vehicle).

[0063] After identifying the participants - Id-Balise1, Id-Balise2, Id-Balise3 -, the application of the AOA Bluetooth positioning technology allows the generation of positioning information relating to each target: a beacon identified Id-Beacon1 is located at an angle θ 1 of -10° relative to the axis of the weapon's barrel; a beacon identified Id-Beacon2 is located at an angle θ 2 of 0° relative to the axis of the weapon's barrel; a beacon identified Id-Beacon3 is located at an angle θ 3 of +30° relative to the axis of the weapon's barrel.

[0064] Thus, AOA-type technologies are particularly well-suited to target positioning. They offer a radio-location method with limited precision that allows for the identification of participants as well as their angular positions within the target's firing position.

[0065] Given that AOA technology has the same axial accuracy properties as UWB, and given that the higher radio frequency of UWB (i.e., from 3.1 to 10.6 GHz) allows a shorter range that is not disrupted by the human body, the use of UWB AOA technology is then particularly advantageous in the case of short-range engagement (<25 m) in urban or indoor environments.

[0066] The use of these technologies in the context of the invention's application is neither ordinary nor immediately applicable to a person skilled in the art. Indeed, it should be noted that the use of AOA technology as proposed in the invention for locating potential targets is the reverse of the conventional use of this technology.

[0067] In the known usage scheme, a constellation of antennas (called anchors) are statically and knownly positioned on the infrastructure in order to triangulate the position of the beacons in a global reference frame.

[0068] In the intended use of the present invention, the antennas (i.e., the anchors) are positioned on the barrel of the shooter's weapon. They are not static but are, on the contrary, in motion. The position of the beacons is then determined by reference to the barrel.

[0069] In one embodiment, the localization means equipping the shooter's weapon have three antennas (ANT1, ANT2, ANT3) defining an orthonormal coordinate system as illustrated in the figure 5 The determination of target location (i.e., the location of the beacons carried by the targets) is performed in a similar way to that with two antennas, but by successively considering two pairs of perpendicular antennas, (ANT1-ANT2) and (ANT1-ANT3). This allows the calculation of two alignment angles: an azimuth 'Φ' and an elevation 'λ'.

[0070] In this embodiment, the radio location function provides 3D information (azimuth and elevation of the beacons in the weapon's coordinate system). The elevation angle can then be used as an additional criterion to identify a target in an image.

[0071] Thus, targets are identified by their approximate angular positions.

[0072] The method of the invention also allows for a precise ballistic calculation of the ammunition's trajectory. The ballistic calculation takes into account the kinematics of the ammunition (from a ballistic calculator), the kinematics and distance to the target (as perceived by the camera), as well as the kinematics of the weapon (as perceived by an inertial measurement unit mounted on the weapon).

[0073] The distance to the target is taken into account by an optical sensor fitted to the weapon.

[0074] In one embodiment, the optical device consists of a camera co-located to the barrel of the weapon, which allows, when a shot (simulated or real) is triggered, to take an image seen from the barrel.

[0075] The optical device is further configured to annotate the type of targets seen, their "skeletons",to calculate for each target the distance and orientation relative to the camera axis, and to construct in the image an impact point of a given munition by performing a ballistic calculation.

[0076] Thus, the combination of information obtained by detecting the relative position of beacons, and information related to the precise ballistic calculation of the munition's trajectory, makes it possible to produce additional information regarding the identification of the participant who crosses the ballistic trajectory of the munition at the time of impact, with the determination of the part hit.

[0077] Using the same example as that of the figure 4 The information produced is illustrated on the figure 6 and consist of indicating that: A human is 12 meters away, at -10° to the gun's axis. A human is 10 meters away, at 0° to the gun's axis, and is hit in the chest (point of impact). A car is 10 meters away, at +30° to the gun's axis.

[0078] Steps in the process of determining shot impact according to an embodiment of the invention are described with reference to the figure 7 .

[0079] The 700 process generally includes steps (707 to 709) operated by first computing means based on radio location data, steps (702 to 706) operated by second computing means based on optical location data, and steps (710 to 714) operated by impact determination means to combine the information calculated by the first computing means and the information calculated by the second computing means and to determine the target hit by the munition and the point of impact.

[0080] Thus, after an initial step 701, performed by firing detection means to detect the moment a round leaves the weapon (start of firing), the process involves steps relating to the acquisition and processing of optical data. A step 702 produces an image seen from the weapon's barrel.

[0081] The image can be produced from one or more cameras mounted on the weapon.

[0082] In one embodiment, the optical device conforms to, or is based on, the device described in Applicant's patent application FR3087528.

[0083] In a subsequent step 703, the process allows, from an appropriate processing, the analysis of the image produced to detect objects present on the image, to perform pose calculations.

[0084] In a subsequent step 704, the process enables a precise ballistic calculation of the trajectory, which takes into account the kinematics of the munition (from a ballistic computer), the kinematics and distance of the target (perceived by the camera) as well as the kinematics of the weapon (as perceived by an inertial measurement unit mounted on the weapon), in order to determine a hit position in the image.

[0085] In a subsequent step 705, the process makes it possible to determine if an object in the image is present at the touched position in the image.

[0086] If an object is detected at the touched position, in a subsequent step 706, the process allows the information relating to the object (its type, its geometry) to be used to identify the position of the tag(s) carried by the touched object.

[0087] To take the example of the figure 6 The process allows the following information to be generated: a human is 12m away; a human is 10m away and is hit; a car is 10m away.

[0088] Returning to the initial step 701 of detecting the moment a round leaves the weapon, the process, concerning the steps related to radio location data, allows, in step 707, the detection, within the weapon's frame of reference, by means of a location system with limited accuracy, of the relative position of beacons located in front of the shooter. This step enables the identification of participants as well as the determination of their angular positions based on the position of the beacons.

[0089] In a subsequent step (708, 709) the process allows for timestamping and storing the angular positions and identifiers of the participants.

[0090] To take the example of the figure 4 , the process allows the following information to be stored: (Id-Balise1 ; θ 1 =-10°); (Id-Balise2 ; θ 2 =0°) ; (Id-Balise3 ; θ 3 =+30°).

[0091] Once both types of radio and video calculations have been carried out, the process continues with a step 710 which cross-references the different information produced in order to identify the participant who crosses the ballistic trajectory of the munition at the time of impact, and to determine the area hit (part of the body for a human or area for another object).

[0092] Thus, according to the example of the figure 6 The combination of all the information obtained by the two data processing methods makes it possible to determine that the human placed 10 meters away and located at 0° relative to the axis of the cannon, was hit in the chest.

[0093] The process then allows 711 to construct a firing report and calculate the attrition due to the position of the ammunition impact.

[0094] The process can continue with a step 712 allowing the shooting report to be sent, on the one hand to the participant who was hit 713, and on the other hand to the shooting exercise instructor 714.

[0095] In an alternative implementation, to improve the system's accuracy and overcome uncertainties, the solution can be extended by placing several markers on the participants at known locations (head, shoulders, knees, etc.). The system then provides multiple position angles per participant, and performs several angle matching operations to accurately locate the participants in the image.

[0096] One alternative implementation involves using several types of localization methods, which can operate in parallel to provide a more robust solution.

[0097] In one embodiment, a visual and inertial odometry solution coupled with radio positioning can allow the system to be immune to radio interference or a smoke signal blocking vision if these interferences do not occur at the same time.

[0098] The device of the present invention is advantageous in cases where a target is completely hidden (smoke grenade, dense vegetation, etc.). Indeed, the function of the "optical device" is then inoperative. However, it becomes possible to implement the method of the invention by statistically simulating the shot. Knowing the approximate position of the targets in the weapon's frame of reference, and considering that the shooter cannot see the targets and fires "by feel," it is perfectly valid to calculate a statistical probability of hitting.

Claims

1. Device for determining the point of impact on a target during practice shooting, the device comprising: - means for detecting shooting (701) configured to determine a time of departure of ammunition from a weapon; - first means for calculating (707, 708, 709) comprising at least two antennas positioned on the barrel of the weapon, configured to determine angular position information of targets located in front of the weapon, the calculation of the angular positions of targets being performed in the reference frame of the barrel of the weapon by the implementation of a beacon locator radio technology referred to as angle of arrival, said beacons being worn by the target; - second means for calculating (702, 703, 704, 705, 706) configured to determine if at least one object present on an image viewed from the weapon is hit by the ammunition, and if yes characterize said at least one object by information concerning the type of object and its position; - means for determining an impact (710) configured to combine the information calculated by the first means for calculating and the information calculated by the second means for calculating to identify the target hit by the ammunition and determine the point of impact on the target.

2. The device according to claim 1 wherein the so called angle-of-arrival technology in the reference frame of the barrel of the weapon is in particular an angle-of-arrival technology for Bluetooth 5.1 or ultra-wide band.

3. The device according to any of the preceding claims wherein the first means for calculating are configured to implement an ultra-wide band radio technology, deployed in the infrastructure, based on a method for calculating distance referred to as time of flight or angle-of-arrival calculation.

4. The device according to any of the preceding claims wherein the first means for calculating are configured to implement a positioning technology by odometry.

5. The device according to any of the preceding claims wherein the second means for calculating are configured to take with at least one camera mounted on the weapon, an image viewed by the barrel at the time of the departure of the ammunition, and to annotate for each object detected on the image information as to its type, its distance and its orientation with respect to the axis of the camera.

6. The device according to the preceding claim wherein the second means of calculating are configured to perform a ballistic calculation of the trajectory of the ammunition using the analysis of the image and construct a point of impact of the ammunition in the image.

7. The device according to any of the preceding claims further comprising means for generating a shooting report and calculating the attrition due to the position of the point of impact of the ammunition on a target.

8. Weapon equipped with a device according to any of the preceding claims.

9. Method (700) for determining the point of impact on a target during practice shooting, the method comprising steps consisting of: - determining (701) a time of departure of ammunition from a weapon; - determining (707, 708, 709) by first means for calculating comprising at least two antennas positioned on the barrel of the weapon, information on the angular positions of targets located in front of the weapon, the calculation of the angular positions of targets being performed in the reference frame of the barrel of the weapon by the implementation of a beacon locator radio technology referred to as angle of arrival, said beacons being worn by the target; - determining (702, 703, 704, 705, 706) if at least one object present on an image viewed by the weapon is hit by the ammunition, and if yes characterize said at least one object by information concerning the type of object and its position; and - combining (710) the angular position information of targets and the information concerning the type of object and its position, to identify the target hit by the ammunition and determine the point of impact on the target.

10. The method according to the preceding claim further comprising a step for generating (711) a shooting report and calculating the attrition due to the position of the point of impact of the ammunition on the target.