Microphone array gunshot positioning method based on bullet velocity measurement

Abstract

The invention discloses a microphone array gunshot positioning method based on bullet velocity measurement. The method comprises the following steps: arranging a multi-channel microphone array to collect gunshot signals containing shock waves and muzzle waves; calculating real-time sound velocity through a temperature compensation model; extracting voiceprint features by using wavelet transform and matching ballistic parameters; acquiring a multi-channel delay inequality based on a generalized cross-correlation algorithm; constructing shock wave and muzzle wave direction vectors and calculating an included angle; calculating the flight distance and speed of the projectile in combination with a Gaussian iteration method; and finally determining the sound source position through a Mach angle model. According to the method, the precision limitation of a traditional method in a complex environment is overcome, and high-robustness and low-delay gunshot positioning is realized.

Description

Technical Field

[0001] This invention belongs to the field of sound source localization technology, and in particular relates to a microphone array gunshot localization method based on projectile velocity measurement. Background Technology

[0002] Gunshot localization primarily employs sound source localization technology, a passive detection technique that locates the sound source by analyzing the propagation of sound signals. Gunshot localization technology mainly involves detecting the unique muzzle waves and Mach waves of gunshots and selecting appropriate sound source localization techniques to calculate the gunshot location. The projectile velocity at shock wave separation is a key parameter; however, current gunshot localization devices still use a uniform projectile velocity model to calculate the gunshot source location, relying on caliber identification information to retrieve the initial projectile velocity from a database, resulting in poor localization accuracy.

[0003] To improve positioning accuracy, Chinese patent application CN112014798A proposes a gunshot positioning device and method based on wavelet transform. It uses wavelet transform to accurately detect muzzle waves and Mach waves, improves the accuracy of wave arrival time difference estimation, and then uses the arrival time difference to locate and orient the gun source, but still uses a uniform velocity model.

[0004] To estimate projectile velocity, Chinese patent document CN106019266B proposed a method for gunshot distance determination and projectile velocity measurement. It uses two sets of microphone arrays as the main model and one set as an auxiliary array for joint calculation to calculate the projectile velocity when the shock wave separates and perform positioning estimation, which effectively improves positioning accuracy, but requires the use of multiple arrays.

[0005] In summary, existing gunshot localization methods employ uniform velocity models for localization estimation, resulting in poor accuracy at long distances. On the other hand, using multi-station estimation of projectile velocity is costly and inconvenient to deploy. Summary of the Invention

[0006] The purpose of this invention is to provide a microphone array gunshot localization method based on projectile velocity measurement, which estimates the projectile velocity when the gunshot signal shock wave separates without increasing the number of microphone array installation points, thereby achieving accurate estimation of the gunshot location.

[0007] To achieve the objective of this invention, a microphone array gunshot localization method based on projectile velocity measurement is provided, comprising the following steps:

[0008] Step 1: Deploy and fix a multi-channel microphone array, which receives multi-channel gunshot signals. Each channel receives a gunshot signal that includes shock wave signals and muzzle wave signals.

[0009] Step 2: Measure the atmospheric temperature and determine the speed of sound based on the formula for the effect of temperature on the propagation of sound in the air;

[0010] Step 3: The gunshot acoustic fingerprint information is obtained by wavelet transform analysis. Based on the projectile acoustic fingerprint information, the initial velocity and ballistic constant of the projectile are obtained by searching the database.

[0011] Step 4: Obtain the shock wave arrival time difference and muzzle wave arrival time difference between each channel, as well as the arrival time difference between the shock wave signal and the muzzle wave signal, through the generalized cross-correlation algorithm.

[0012] Step 5: Determine the shock wave direction vector and the muzzle wave direction vector based on the shock wave arrival time difference and the relative positions of the microphones in the microphone array;

[0013] Step 6: Determine the angle between the shock wave direction vector and the muzzle wave direction vector.

[0014] Step 7: Use the time difference of arrival, included angle, initial velocity of the projectile, and ballistic constant to obtain the projectile flight distance at the shock wave separation using the Gaussian iteration method, and then determine the projectile velocity;

[0015] Step 8: Determine the Mach angle between the shock wave and the trajectory line based on the projectile velocity, and then determine the distance to the sound source point based on the projectile flight distance, the time difference of arrival between the shock wave and the muzzle wave, and the angle between the direction vectors of the shock wave and the muzzle wave.

[0016] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the above-described method for locating gunshots using a microphone array based on projectile velocity measurement.

[0017] A non-transitory computer-readable storage medium storing computer instructions for causing the computer to execute the aforementioned microphone array gunshot localization method based on projectile velocity measurement.

[0018] A computer program product includes computer program instructions that, when executed on a computer, cause the computer to perform the aforementioned microphone array gunshot localization method based on projectile velocity measurement.

[0019] Compared with the prior art, the significant advancement of the present invention is that it uses a database pre-training method to estimate the projectile velocity without increasing the number of arrays, and improves the distance estimation method by correcting the projectile velocity, thereby improving the accuracy of gunshot localization.

[0020] To more clearly illustrate the functional characteristics and structural parameters of the present invention, further explanation is provided below in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0022] Figure 1 This is a flowchart of the steps of the present invention;

[0023] Figure 2 This is a graph showing the relative range error of the traditional uniform velocity model as a function of range.

[0024] Figure 3 This is a graph showing the variation of the relative range error of the velocity decay model of this invention with the range. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] This invention provides a microphone array gunshot localization method based on projectile velocity measurement, combined with... Figure 1 This includes the following steps:

[0027] Step 1: Deploy and fix a four-channel microphone array to receive four channels of 7.62mm caliber gunshot signals. Each channel receives a gunshot signal containing a shock wave signal s. a and muzzle wave signal s b The subscript a represents the shock wave signal, and b represents the muzzle wave signal;

[0028] Step 2: Measure the atmospheric temperature t, and calculate the speed of sound c according to the formula for the effect of temperature on the propagation of sound in the air; the specific formula is as follows: c = 331.3 + 0.606t;

[0029] Step 3: The gunshot acoustic signature information is obtained through wavelet transform analysis. Based on the projectile acoustic signature information, the initial velocity V0 and the ballistic constant D of the projectile are obtained from the database. In this embodiment, the 7.62mm caliber corresponds to V0 = 833.7m / s and D = 90.82.

[0030] Step 4: Obtain the shock wave arrival time difference ρ between each channel using the generalized cross-correlation algorithm. ij Time difference λ between the muzzle wave and the muzzle wave ij and shock waves a With muzzle wave s b Time difference of arrival τ between ab , where ρ ijλ represents the shock wave arrival time difference between the i-th and j-th channels. ij This represents the time difference of arrival of the muzzle wave between the i-th channel and the j-th channel.

[0031] Step 5: Based on the shock wave arrival time difference ρ ij The relative positions r between the microphones in the four-channel microphone array ij Solve for the shock wave direction vector t a Similarly, the muzzle wave direction vector t can be obtained. b ;

[0032] The shock wave direction vector t a :

[0033] Δρ=[ρ i2 , ..., ρ 34 ] T ;

[0034] ΔR=[r 12 , ..., r 34 ] T ;

[0035] Δρ=ΔR·t a / c;

[0036] Where Δρ is the shock wave arrival time difference ρ between all channels. ij The array is arranged in a column vector, where ΔR represents the relative positions r between the microphone array channels. ij A matrix arranged in this way, ρ ij r represents the shock wave arrival time difference between the i-th channel and the j-th channel. ij This represents the relative positional relationship between the i-th and j-th array elements, where c is the speed of sound determined in step 2.

[0037] muzzle wave direction vector t b :

[0038] Δγ=[γ 12 , ..., γ 34 ];

[0039] ΔR=[r 12 , ..., r 34 ] T ;

[0040] Δγ=ΔR·t b / c;

[0041] Where Δγ is the time difference γ of the muzzle wave arrival between all channels. ij A column vector, γ ij This represents the time difference of arrival of the muzzle wave between the i-th channel and the j-th channel.

[0042] Step 6: Calculate the shock wave direction vector t a With muzzle wave direction vector t b The included angle θ between them;

[0043] The included angle θ is specifically shown in the following formula:

[0044]

[0045] Step 7: Calculate the projectile flight distance x at shock wave separation using the time difference of arrival, included angle, initial velocity of the projectile, and ballistic constant, and then calculate the projectile velocity v.

[0046]

[0047] Step 8: Determine the Mach angle between the shock wave and the trajectory line based on the projectile velocity, and then determine the distance k of the sound source point based on the projectile flight distance, the time difference of arrival between the shock wave and the muzzle wave, and the angle between the direction vectors of the shock wave and the muzzle wave.

[0048]

[0049] In this embodiment, gunshot data collected at 169m, 446m, and 533m were analyzed and processed. Distance estimation was performed using the method of this patented patent and a traditional uniform velocity model. The results are as follows: Figure 2 As shown, in the traditional uniform velocity model, the positioning error gradually increases with increasing distance; for example... Figure 3 As shown, the positioning error of the method in this patent is significantly reduced, and does not increase significantly with increasing distance.

[0050] This embodiment estimates the projectile velocity during shock wave separation using a single-station microphone array, improving the distance estimation method and achieving a high level of accuracy, further demonstrating the effectiveness of the patented method.

[0051] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for gunshot localization based on a microphone array with projectile velocity estimation, characterized in that, The method comprises the following steps: Step 1, arranging and fixing a multi-channel microphone array to receive a multi-channel gunshot signal, each channel receiving a gunshot signal containing a shock wave signal and a muzzle wave signal; Step 2, measuring the atmospheric temperature and determining the sound velocity according to the formula of the influence of temperature on the propagation of sound in air; Step 3, obtaining the bullet soundprint information by wavelet transform analysis and recognition, and searching the database to obtain the initial velocity and ballistic constant of the bullet according to the bullet soundprint information; Step 4, obtaining the shock wave arrival time difference and the muzzle wave arrival time difference between channels and the arrival time difference between the shock wave signal and the muzzle wave signal by generalized cross-correlation algorithm; Step 5, determining the shock wave direction vector and the muzzle wave direction vector according to the shock wave arrival time difference and the relative position between each microphone of the microphone array; Step 6, determining the included angle between the shock wave direction vector and the muzzle wave direction vector. Step 7, obtaining the bullet flight distance when the shock wave separates by Gaussian iteration method according to the arrival time difference, the included angle, the initial velocity of the bullet, and the ballistic constant, and further determining the bullet speed; Step 8, determining the Mach angle of the shock wave and the ballistic line according to the bullet speed, and further determining the sound source point distance according to the bullet flight distance, the arrival time difference between the shock wave and the muzzle wave, and the included angle between the shock wave and the muzzle wave direction vector.

2. The gunshot locating method based on the projectile velocity measurement of the microphone array according to claim 1, wherein, The shock wave direction vector and the muzzle wave direction vector of step 5 are calculated as follows: The shock direction vector t a : Δρ = [ρ 12 , …, ρ ij ] T ; AR = [r 12 ,..., r ij ] T ; Δρ = ΔR - t a / c; wherein, Δρ is the shock arrival time difference between all channels ρ ij a column vector, ΔR is the relative position between each channel of the microphone array r ij a matrix, ρ ij represents the shock arrival time difference between the i-th channel and the j-th channel, r ij represents the relative position relationship between the i-th element and the j-th element, and c is the sound speed determined in step 2. Muzzle wave direction vector t b : Δγ = [γ 12 ,..., γ ij ] ; AR = [r 12 ,..., r ij ] T ; Δγ = ΔR - t b / c; where Δγ is the difference in the arrival time of the muzzle wave between all channels γ ij a column vector, γ ij denotes the difference in the arrival time of the muzzle wave between the i-th and j-th channels.

3. The gunshot locating method based on the projectile velocity measurement of the microphone array according to claim 2, characterized in that, The included angle θ of step 6 is specifically as follows:

4. The gunshot locating method based on the projectile velocity measurement of the microphone array according to claim 3, characterized in that, Step 7 is specifically as follows: wherein τ ab is the time difference of arrival between the shock wave signal s a and the muzzle wave signal s b , v is the projectile velocity, x is the projectile flight distance at the shock wave separation, V0 is the initial projectile velocity, D is the ballistic constant, and θ is the included angle between the shock wave direction vector t a and the muzzle wave direction vector t b .

5. The gunshot locating method based on the microphone array and the projectile velocity estimation according to claim 4, wherein, The sound source point distance k of step 8 is specifically as follows:

6. The gunshot locating method based on the projectile velocity measurement of the microphone array according to claim 1, wherein, The number of channels is four.

7. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the program to realize the method of any one of claims 1-6.

8. A non-transitory computer-readable storage medium, comprising: The non-transitory computer readable storage medium stores computer instructions for causing the computer to execute the method of any one of claims 1-6.

9. A computer program product comprising computer program instructions, characterised in that, When the computer program instructions run on the computer, the computer executes the method of any one of claims 1-6.

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