Technical field

[0001] The present invention relates generally to a three-dimensional Location Of Miss And Hit, LOMAH, system for locating shots from supersonic bullets.

Background art

[0002] There are a variety of LOMAH systems on the market today which are used for electronic hit scoring during practice and improvement of a shooter. Most LOMAH systems have a target platform comprising a set of acoustic sensors used for detecting shot information, i.e. the time of arrival of sound or shock waves at the different acoustic sensors that are comprised in the set of sensors. The difference in time of arrival or the detection time at the different acoustic sensors are then used to calculate and display an electronic picture of the target board. Using a LOMAH system saves time during practice for a shooter, since the result of a shot is directly displayed at the position of the shooter, who does not need to walk up to the target to see hits and misses.

[0003] In order to increase the accuracy of the LOMAH system, the target platform is also provided with a temperature sensor. As is well known in the art, the speed of sound in air varies with the temperature of air and it is therefore important to know the ambient temperature when performing calculations in order to get a correct picture of the hits and misses. However, there is also a drawback with using temperature sensors if they do not show the correct value of the ambient temperature. The temperature sensor is most of the time provided on the target platform, which is often exposed to direct sunlight, since the target platform is placed in open areas. In such cases, the errors in measuring the ambient temperature are often substantial, having a significant impact on the calculation of hit and misses. One solution could be to place the temperature sensor at another more protected location to avoid direct sunshine. This makes the system more complex and will also add to the time it takes to set up the system. Furthermore, when the sun moves usually also the temperature sensor needs to be moved. [0004] Thus, there is a need to further improve the accuracy of LOMAH systems and at the same increase the simplicity of use for such systems.

Summary of invention

[0005] An object of the present invention is to improve the accuracy of a LOMAH system without the use of a temperature sensor and which gives a great flexibility regarding the configuration, arrangement, and number of sensors in a target platform of the LOMAH system.

[0006] This is accomplished by a three-dimensional LOMAH, system for locating shots from supersonic bullets, comprising a target platform in which a processor and a memory are provided and a sensor array is provided on the upper surface of the target platform, the sensor array comprising at least four acoustic sensors arranged in two rows, wherein the memory comprises instructions which when executed by the processor causes the three-dimensional LOMAH system to detect, with the acoustic sensors, shot information about a shot generated by a shooter and passing proximate the target platform, register the time of detection for each acoustic sensor, create a set of time vectors for every combination of two acoustic sensors based on the registered time of detection, input the set of time vectors into a target calculation module trained using a Machine Learning, ML, model that has been subjected to a large amount of training data by using randomized input data, which target calculation model is configured to create the set of time vectors for every combination of two sensor and correlate to actual hits and misses of the shots in the training data based on the randomized input data, which target calculation module is configurable, with use of a set of training data comprising a starting point, a velocity, an impact angle and hit coordinates of the supersonic bullets, to calculate a bullet impact and trajectory based on the input set of time vectors, and output the bullet impact and trajectory on a display connected to the LOMAH system.

[0007] Even though a number of configurations, arrangements and different numbers of sensors have been described above it is possibly with many other configurations, arrangements and numbers of sensors. One advantage with the present invention is that the target calculation platform may be configured in many different ways, since the calculations performed on the created time vectors for every combination of two acoustic sensors for determining the bullet impact and trajectory of the shot are based on the same configuration and setup that was used when the LOMAH system was trained. Thus, this gives a great flexibility when designing the LOMAH system, since the configuration, arrangement and number of sensors may be easily adapted to the specific purpose that the LOMAH system is to perform.

[0008] In a preferred embodiment of the three-dimensional LOMAH system, the target calculation module is configurable to calculate the hit or miss in a 3- dimensional space, as defined in a standard right-handed Cartesian coordinate system, the velocity of the supersonic bullet and an impact angle in a x-direction and an impact angle in a y-direction based on the created set of time vectors.

[0009] In another preferred embodiment of the three-dimensional LOMAH system, the target calculation module is further configurable to calculate an ambient temperature, by including the position of the shooter and the ambient temperature in the randomized input data.

[0010] In yet another preferred embodiment of the three-dimensional LOMAH system, the target calculation module is configurable to calculate the impact angle in the x-direction in a range of ± 30 degrees and the impact angle in the y-direction in a range of ± 15 degrees.

[0011 ] In another exemplary embodiment of the three-dimensional LOMAH system, the sensor array comprises at least six sensors arranged in two rows.

[0012] In yet another exemplary embodiment of the three-dimensional LOMAH system, the sensor array comprises eight sensors arranged in three rows, a first row, a second row and a middle row arranged between the first row and the second row and wherein the middle row comprises two sensors.

[0013] In another exemplary embodiment of the three-dimensional LOMAH system, the two sensors in the middle row are arranged horizontally offset in relation to the sensors in the first row and the second row, preferably with a distance that is half the distance of the sensors in the first row and the second row.

[0014] In an exemplary embodiment of the three-dimensional LOMAH system, each sensor in the sensor array is arranged with an angle in the range of 30-70 degrees in relation to the horizontal extension of the target platform.

Brief description of drawings

[0015] The invention is now described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 shows a perspective view of a target platform of the LOMAH system,

Fig. 2 shows a side view of a part of the front of the target platform, indicating an angle (a) of an acoustic sensor in relation to the horizontal extension of the target platform,

Fig. 3 shows a schematic block diagram of an embodiment of the LOMAH system including the target platform and a display.

Description of embodiments

[0016] In the following, a detailed description of present invention will be made.

[0017] Turning now to Fig. 1 one embodiment of a target platform 30 of a LOMAH system 100 will be described. The LOMAH system 100 in this embodiment is a three-dimensional LOMAH system, i.e. it is not only capable to detect a shot in a plane x and y, but can also calculate the angle at which the shot hits the target. In Fig. 1 the 3-dimensional space is defined in a standard right-handed Cartesian coordinate system. A further benefit with the LOMAH system according to the present invention is that also is capable to calculate the ambient temperature without the need of a temperature sensor, which will be explained later.

[0018] Inside of the target platform 30 there is provided a target calculation module 40 comprising a processor 2 and a memory 4, as shown in Fig. 3. The target platform 30 is further provided with a sensor array on the upper surface of the target platform 30. The sensor array comprises a plurality of acoustic sensors 6, 8, 10, 12, 14, 16, 18, 20. The number of acoustic sensors is at least four 6, 8, 10, 12 in which case the acoustic sensors 6, 8, 10, 12 are arranged in two rows. Different configurations and the number of acoustic sensors and rows will be further discussed below.

[0019] The memory 4 comprises instructions which when executed by the processor 2 causes the three-dimensional LOMAH system 100 to detect, with the acoustic sensors 6, 8, 10, 12, shot information about a shot generated by a shooter and passing proximate the target platform 30. The detection of the acoustic sensors 6, 8, 10, 12 is triggered when the sound or shock wave reaches above a certain threshold. It is believed to be within the knowledge of a person skilled in the art to determine the threshold level depending on ambient surroundings and the set up of the LOMAH system 100, such as type of shots and the like. The time of detection for each acoustic sensor 6, 8, 10, 12 is registered by the target calculation module 40. The time of detection is then used by the target calculation module 40 to create a set of time vectors for every combination of two acoustic sensors 6-8; 6-10; 6-12; 8-10; 8-12; 10-12. The set of time vectors is input into the target calculation module 40 to calculate a bullet impact and trajectory based on the input set of time vectors.

[0020] The target calculation module 40 has been trained using a Machine Learning, ML, model that has been subjected to a large amount of training data. For any given configuration of sensors on the target platform 30 the target calculation model 40 is trained by using randomized input data including the ambient temperature and the position of the shooter. Based on the input data the target calculation module 40 creates the set of time vectors for every combination of two sensors and is then correlated to actual hit and misses of the shots in the training data. The end result is a target calculation module 40 that is capable to determine the hit or miss in a 3-dimensional space, i.e. in the x-, y- and z-direction of a standard right-handed Cartesian coordinate system, based on the created set of time vectors. Since the hit is determined in 3 dimensions it is also possible to calculate the velocity of the bullet. Furthermore, the target calculation module 40 is also capable of determining an impact angle 0 in the x-direction and an impact angle <t> in the y-direction together with the ambient temperature. Thus, by using the target calculation module in the present invention it is possible to determine the hit of a shot very accurate and without the need to use the ambient temperature when performing the calculations.

[0021] It is to be understood that depending on the number of sensors and the configuration thereof the detection area of the LOMAH system 100 may vary and also the capability of detecting rough misses. Generally, the capability of detecting rough misses increase with the number of sensors and the field of view of the sensors. For a typical target calculation module 40 according to the present invention the output is, the x-, y- and z-coordinates in a three-dimensional space above the target platform, the impact angle 0 in the x-direction within a field of view of ± 30 degrees, the impact angle <t> in the y-direction within a field of view of ± 15 degrees and the ambient temperature. By increasing the amount of training data, it is of course also possible increase the field of view for the impact angle if this is desirable.

[0022] As mentioned above the number of acoustic sensors 6, 8, 10, 12 may vary and also be configured in different ways. In the embodiment that is shown in Fig. 1 , the sensor array comprises eight sensors 6, 8, 10, 12, 14, 16, 18, 20 arranged in three rows, a first row, a second row and a middle row arranged between the first row and the second row. The first row and the second row each comprises three acoustic sensors 6, 18, 10 and 8, 16, 12, respectively, and the middle row comprises two sensors 14, 20. In a preferred embodiment the two sensors 14, 20 in the middle row are arranged horizontally offset in relation to the sensors in the first row and the second row. The two sensors 14, 20 of the middle row may be arranged horizontally offset with a distance that is half the distance between the sensors 6, 8, 10, 12, 16, 18 in the first row and the second row.

[0023] In another embodiment, which is shown Fig. 3, there are four acoustic sensors 6, 8, 10, 12 which are arranged in two rows, the first row comprises the acoustic sensor 6, 10 and the second row comprises the acoustic sensors 8, 12. In an alternative embodiment the sensor array comprises six sensors 6, 8, 10, 12, 16, 18 arranged in two rows, the first row comprises the acoustic sensor 6, 18, 10 and the second row comprises the acoustic sensors 8, 16, 12. The acoustic sensors 16, 18 are shown with dotted lines as they are optional.

[0024] Turning now to Fig. 2 the arrangement and direction of each acoustic sensor will be further discussed, with acoustic sensor 16 as an example in Fig. 2. Each acoustic sensor 6, 8, 10, 12, 14, 16, 18, 20 in the sensor array may be arranged with an angle a in the range of 0-90 degrees in relation to the horizontal extension of the target platform 30. However, preferably the acoustic sensor 6, 8, 10, 12, 14, 16, 18, 20 in the sensor array are arranged in the range of 30-70 degrees. The angle a of the different acoustic sensors may be the same for all acoustic sensors 6, 8, 10, 12, 14, 16, 18, 20, but may also vary depending on the embodiment. The benefit with having an angle a in relation to the horizontal extension of the target platform 30 is that it is easier for water caused by rainfall to slide of the acoustic sensors more easily. Another benefit is that the target area can be increased when arranging the acoustic sensors with an angle.

[0025] Even though a number of configurations, arrangements and different numbers of sensors have been described above it is possibly with many other configurations, arrangements and numbers of sensors. One advantage with the present invention is that the target calculation platform 40 may be configured in many different ways, since the calculations performed on the created time vectors for every combination of two acoustic sensors for determining the bullet impact and trajectory of the shot are based on the same configuration and setup that was used when the LOMAH system was trained. Thus, this gives a great flexibility when designing the LOMAH system, since the configuration, arrangement and number of sensors may be easily adapted to specific purpose that the LOMAH system is to perform.