Acoustic positioning device and method for coal mine auxiliary transportation digital twin system

Abstract

The invention discloses a sound wave positioning device and method for a coal mine auxiliary transportation digital twin system. According to the device, two loudspeakers are installed on the side wall of a roadway of an auxiliary transportation equipment operation area at intervals; the omnidirectional microphone and the edge computing node are mounted on the auxiliary transportation equipment; the method comprises installing the sound wave positioning device; constructing an asymmetric sound field; off-line RSS acquisition is carried out; constructing a multi-dimensional RSS fingerprint vector according to the received interference intensity, and constructing a gradient fingerprint image based on the multi-dimensional RSS fingerprint vector; establishing a fingerprint database; acquiring an RSS vector Rtest of a current to-be-positioned point, converting the RSS vector Rtest into a corresponding to-be-matched gradient fingerprint image gtest, and performing fingerprint matching by using a fingerprint image matching algorithm based on a discrete Frechet distance to obtain position information; and digital twinning integration. According to the device and the method, the auxiliary transportation equipment can be quickly and accurately positioned in a complex coal mine environment, and the safety and the efficiency of mine operation can be effectively improved through real-time feedback and visual monitoring.

Description

Technical Field

[0001] The present invention belongs to the field of intelligent positioning technology, and specifically relates to an acoustic wave positioning device and method for a coal mine auxiliary transportation digital twin system. Background Art

[0002] With the digital transformation of the mining industry, the application of digital twin technology in mining operations has become more and more extensive. Digital twins achieve real-time monitoring of equipment through information mapping between the physical entity and virtual model of the equipment. As the underground working environment of coal mines becomes increasingly complex, the management and scheduling of coal mine auxiliary transportation systems have become more difficult. Combined with digital twin technology, real-time monitoring and status analysis of transportation equipment and personnel can be achieved, helping managers to perform more efficient scheduling and maintenance. However, the implementation of the coal mine auxiliary transportation digital twin system is inseparable from the support of high-precision positioning data. How to achieve accurate positioning of coal mine auxiliary transportation equipment in the complex underground environment has become an important issue to improve the efficiency of coal mine auxiliary transportation and ensure safety.

[0003] For coal mine auxiliary transportation equipment, traditional positioning methods such as GPS and lidar often face problems such as signal failure, high equipment cost, and unsatisfactory positioning accuracy in underground environments, making it difficult to meet the requirements of digital twins for data real-time and accuracy. The high-precision positioning method based on sound waves provides a new solution. Sound waves have the characteristics of strong penetration and good anti-interference, and can play an effective role in an environment with restricted electromagnetic waves. However, there are some problems with the current acoustic wave positioning technology used in coal mines. For example, the complexity of the mine environment will cause the propagation speed and path of the sound waves to be affected by factors such as temperature, humidity, and air pressure, which will seriously affect the positioning accuracy. In addition, the traditional acoustic wave positioning system usually requires multiple receivers to work together to calculate the position, and the hardware equipment is relatively complex. For this reason, it is urgent to provide a low-cost acoustic wave positioning device and method for the digital twin system of coal mine auxiliary transportation to effectively realize the high-precision positioning requirements in the complex environment underground. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides an acoustic wave positioning device and method for a coal mine auxiliary transportation digital twin system. The device has low investment cost and can realize rapid and accurate positioning of auxiliary transportation equipment in complex mine or tunnel environments. This method can not only realize rapid and accurate positioning of auxiliary transportation equipment in complex coal mine environments, but also improve the safety and efficiency of mine operations through real-time feedback and visual monitoring.

[0005] In order to achieve the above-mentioned object, the present invention provides an acoustic wave positioning device for a coal mine auxiliary transportation digital twin system, including an acoustic wave transmitter, a controller, an acoustic wave receiver and an edge computing node;

[0006] The sound wave transmitter is two loudspeakers, which are installed on the side wall of the lane in the operation area of ​​the auxiliary transportation equipment at a set distance, and are used to continuously emit sound wave signals and generate an interference sound field composed of superimposed different frequency components;

[0007] The controller is connected to the sound wave transmitter and is used to control the action of the sound wave transmitter;

[0008] The sound wave receiver is an omnidirectional microphone, which is installed on the auxiliary transportation equipment and is used to receive the sound wave signal and send the sound wave signal to the edge computing node;

[0009] The edge computing node is installed on the auxiliary transportation equipment and connected to the sound wave receiver, so as to analyze and process the sound wave signal and obtain the location information of the auxiliary transportation equipment based on the processed sound wave signal.

[0010] In order to facilitate the real-time display of the obtained location information of the auxiliary transportation equipment, a display is also included, which is connected to the edge computing node and is used to display the location information sent by the edge computing node in real time.

[0011] In the present invention, two speakers are installed at intervals on the sidewalls of the tunnel in the transport area, and the two speakers are used to generate an interference sound field superimposed by different frequency components. At the same time, an omnidirectional microphone and an edge computing node are installed on the auxiliary transport equipment, and the omnidirectional microphone receives the unique RSS distribution formed by the change of position. In this way, the edge computing node can realize the rapid and accurate positioning of the auxiliary transport equipment based on the RSS data at a low cost. The device has a low investment cost and can realize the rapid and accurate positioning of the auxiliary transport equipment in a complex mine or tunnel environment.

[0012] The present invention also provides an acoustic wave positioning method for a coal mine auxiliary transportation digital twin system, which adopts an acoustic wave positioning device for a coal mine auxiliary transportation digital twin system, and is characterized in that it includes the following steps:

[0013] Step 1: Install the sonar positioning device;

[0014] Install two speakers at a set distance on the side wall of the lane in the auxiliary transportation equipment operation area, and ensure that the sound wave signals emitted by the two speakers can cover the auxiliary equipment operation area; install edge computing nodes and sound wave receivers on the auxiliary transportation equipment, and establish a communication connection between the edge computing nodes and the sound wave receivers;

[0015] Step 2: Asymmetric sound field construction;

[0016] S21: Select the OFDM signal as the transmission signal of the two speakers, and use the ZC sequence to modulate the signal in the frequency domain to generate an interference sound field composed of superposition of different frequency components;

[0017] S22: Phase modulate the OFDM signal; set a unique initial phase difference for each subcarrier so that the interference sound field generated by each subcarrier pair is translated to different degrees in the x-axis direction to break the symmetry of the overall sound field and ensure that the RSS features at different positions have sufficient differences;

[0018] S23: Perform frequency response equalization processing on the signal to ensure the stability of the interference sound field; first calculate the compensation factor set H(n) according to formula (1), and then adjust the gain according to the compensation factor set H(n) to match the target frequency response; then, extend the OFDM baseband signal to the required frame length through frequency domain interpolation to generate a time domain signal, and generate a target sound field signal through inverse Fourier transform to ensure that the interference sound field has good spatial diversity and position differentiation ability, so as to generate a stable interference sound field with high RSS spatial uniqueness in the target area;

[0019]

[0020] Where n = 0, 1, ..., N ZC -1;Q target (n) is the target flat frequency response curve, Q(n) is the frequency response curve of the loudspeaker;

[0021] Step 3: Offline RSS collection;

[0022] Preset multiple candidate positioning points in the auxiliary transport operation area, use the acoustic wave receiver to collect RSS data at the multiple candidate positioning points in turn, and record the RSS data of each candidate positioning point;

[0023] Step 4: Generate gradient fingerprint image;

[0024] S41: After receiving the RSS data, the acoustic wave receiver demodulates to extract the interference intensity information of each subcarrier; when N sampling points are obtained after t time, and the frame length is set to N a When , the N sampling points are reconstructed into a size of The matrix Γ of

[0025]

[0026] S42: Performing a fast Fourier transform on each column of the matrix Γ to convert the time domain signal into frequency domain information; obtaining the interference intensity of each frequency component by extracting the frequency point corresponding to the preset frequency in the frequency domain signal; constructing a multidimensional RSS fingerprint vector according to the received interference intensity;

[0027] S43: constructing a gradient fingerprint image based on the multi-dimensional RSS fingerprint vector; on a two-dimensional plane, using the frequency index as the horizontal coordinate and the interference signal intensity as the vertical coordinate, plotting the points corresponding to each frequency component, and connecting these points in sequence to form a gradient fingerprint image;

[0028] Step 5: Establish a fingerprint library in the positioning area; divide the target area into discrete location spaces Form a candidate point grid, where N l is the number of candidate points; for each candidate point l σ (x σ ,y σ ), where 1≤σ≤N l , collect N f The interference strength of the subcarrier pairs is calculated and the RSS fingerprint vector is constructed. Among them, r σ,j Indicates that the jth subcarrier pair is at position l σ The interference intensity is taken as the subcarrier index j, and the interference intensity r σ,j As the ordinate, construct a gradient fingerprint image g for each position σ ={ <j,r σ,j >}, and finally form the fingerprint image library of the entire position space L

[0029] Step 6: Real-time fingerprint matching;

[0030] S61: Online RSS collection: When the auxiliary transportation equipment is running, the two speakers are synchronously controlled to send signals. At the same time, the microphone is used to receive RSS data in real time, and the real-time received RSS data is converted into a real-time fingerprint vector according to formula (3) to obtain the RSS vector R of the current point to be located. test ;

[0031] R test =[r test,1 ,r test,2 ,…,r test,n ] (3);

[0032] S62: Convert the real-time fingerprint vector into the corresponding gradient fingerprint image g to be matched test ;

[0033] S63: Perform fingerprint matching using a fingerprint image matching algorithm based on discrete Frechet distance; obtain a gradient fingerprint image g based on the fingerprint image library G according to formula (4) test Frechet distance D F ; For each candidate point l in the fingerprint database σ ∈L fingerprint image g σ, according to formula (5), calculate its gradient fingerprint image g to be matched test The similarity d F (g test ,g σ ), select the candidate point corresponding to the fingerprint image with the smallest similarity as the target position l * , and output the target position l * As location information of auxiliary transportation equipment;

[0034]

[0035] In the formula, g i is a candidate fingerprint image, which comes from the fingerprint image library G; α(t) and β(t) are two increasing mapping functions; ∥·∥ is the Euclidean distance;

[0036] Step 7: Digital twin integration;

[0037] S71: Establish a communication connection between the edge computing node and the digital twin system;

[0038] S71: Data transmission and virtualization stage; after the edge computing node obtains the location data of the auxiliary transportation equipment in real time, it transmits the location data to the digital twin system through the wireless communication network. The digital twin system generates a virtual model of the auxiliary transportation equipment based on the real-time location data, and dynamically displays the virtual model in the pre-built three-dimensional model of the mine environment. At the same time, it is displayed in real time through the display screen to dynamically reflect the location and operating status of the auxiliary transportation equipment in the mine.

[0039] S72: Real-time monitoring and optimization stage; through the digital twin system, the status, location and trajectory of the auxiliary transportation equipment are monitored in real time, and virtual modeling and precise tracking of the operating status of the auxiliary transportation equipment are achieved, providing data support for production scheduling optimization and equipment health management.

[0040] As a preferred embodiment, in S71 of step seven, the digital twin system continuously updates the position of the virtual model of the auxiliary transportation equipment according to a set time interval to ensure that the position of the virtual model of the auxiliary transportation equipment is highly consistent with the actual limit position of the auxiliary transportation equipment.

[0041] As a preferred embodiment, in step 2 S21, the length N is obtained by formula (6) ZC The ZC sequence zc[n];

[0042]

[0043] In the formula, u and q are sequence parameters, and u and N ZC Being mutually prime ensures that the ZC sequence has good autocorrelation characteristics, and i is the imaginary unit.

[0044] Furthermore, in order to remind relevant managers in time through alarms when abnormalities occur, so that relevant managers can take correct response measures in a timely and effective manner, in step seven S72, when the digital twin system detects that the position of the auxiliary transportation equipment is abnormal or the positioning data is abnormal, it sends a warning message to the display screen, and at the same time, controls the alarm device connected to it to make an audible and visual alarm.

[0045] In the present invention, two loudspeakers are first controlled to generate coherent sound waves, forming an interference sound field with alternating strengths and weaknesses in space. At the same time, OFDM signals are selected as the transmission signals of the two loudspeakers located on the tunnel wall, and the baseband signals are phase modulated and frequency-response balanced, which can generate a stable asymmetric interference sound field with high RSS spatial diversity in the target area. In this way, it can be ensured that in a complex mine tunnel environment, when the auxiliary transportation equipment is in different positions, the intensity of the signal received by the microphone deployed thereon can form a unique RSS distribution with the change of position, thereby providing a reliable basis for the subsequent positioning process. The construction of the RSS fingerprint library in advance in the offline process is conducive to the rapid and accurate matching of the target position of the auxiliary transportation equipment through the Frechet distance algorithm when the RSS data is obtained in real time in the subsequent process. By combining the fingerprint library with the matching algorithm of the Frechet distance, accurate position estimation can be achieved, and centimeter-level positioning accuracy can still be provided even in a complex mine or tunnel environment. After obtaining the real-time position data, a virtual model of the auxiliary transportation equipment is constructed through the digital twin system, and displayed in real time in the pre-built three-dimensional module of the mine environment. In this way, the real-time position information of the auxiliary transportation equipment in the coal mine can be synchronized with the virtual model using the digital twin system, thereby achieving accurate correspondence between the physical equipment and the virtual environment. In the digital twin system, the position of the virtual auxiliary transportation equipment changes synchronously with the physical auxiliary transportation equipment. The system will adjust the position, direction and movement trajectory of the auxiliary transportation equipment in the virtual environment in real time, which can facilitate relevant personnel to monitor the operating status, current position and travel path of the auxiliary transportation equipment in real time on the visual interface, and can provide technical support for production scheduling optimization and equipment health management.

[0046] This method overcomes the limitations of existing coal mine positioning technology. It can not only quickly and accurately realize the positioning of auxiliary transportation equipment in complex coal mine environments, but also improve the safety and efficiency of mine operations through real-time feedback and visual monitoring. It helps managers to accurately control the operating status of coal mine auxiliary transportation equipment, significantly reduce the failure rate, and improve the safety factor of operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the arrangement of the positioning device in the present invention;

[0048] Figure 2 is a flow chart of the positioning method in the present invention;

[0049] Figure 3 In the present invention, a Schematic diagram of fingerprint image at the position;

[0050] Figure 4 In the present invention, b Schematic diagram of fingerprint image at the location. DETAILED DESCRIPTION

[0051] The present invention will be further described below in conjunction with the accompanying drawings.

[0052] like Figure 1 As shown, the present invention provides an acoustic wave positioning device for a coal mine auxiliary transportation digital twin system, including an acoustic wave transmitter, a controller, an acoustic wave receiver and an edge computing node;

[0053] The sound wave transmitter is two loudspeakers, which are installed on the side wall of the lane in the operation area of ​​the auxiliary transportation equipment at a set distance, and are used to continuously emit sound wave signals and generate an interference sound field composed of superimposed different frequency components;

[0054] The controller is connected to the sound wave transmitter and is used to control the action of the sound wave transmitter;

[0055] The sound wave receiver is an omnidirectional microphone, which is installed on the auxiliary transportation equipment and is used to receive the sound wave signal and send the sound wave signal to the edge computing node;

[0056] The edge computing node is installed on the auxiliary transportation equipment and connected to the sound wave receiver, so as to analyze and process the sound wave signal and obtain the location information of the auxiliary transportation equipment based on the processed sound wave signal.

[0057] In order to facilitate the real-time display of the obtained location information of the auxiliary transportation equipment, a display is also included, which is connected to the edge computing node and is used to display the location information sent by the edge computing node in real time.

[0058] In the present invention, two speakers are installed at intervals on the sidewalls of the tunnel in the transport area, and the two speakers are used to generate an interference sound field superimposed by different frequency components. At the same time, an omnidirectional microphone and an edge computing node are installed on the auxiliary transport equipment, and the omnidirectional microphone receives the unique RSS distribution formed by the change of position. In this way, the edge computing node can realize the rapid and accurate positioning of the auxiliary transport equipment based on the RSS data at a low cost. The device has a low investment cost and can realize the rapid and accurate positioning of the auxiliary transport equipment in a complex mine or tunnel environment.

[0059] like Figures 2 to 4As shown, the present invention also provides a sonic positioning method for a coal mine auxiliary transportation digital twin system, using a sonic positioning device for a coal mine auxiliary transportation digital twin system, characterized in that it includes the following steps:

[0060] Step 1: Install the sonar positioning device;

[0061] Install two speakers at a set distance on the side wall of the lane in the auxiliary transportation equipment operation area, and ensure that the sound wave signals emitted by the two speakers can cover the auxiliary equipment operation area; install edge computing nodes and sound wave receivers on the auxiliary transportation equipment, and establish a communication connection between the edge computing nodes and the sound wave receivers;

[0062] Step 2: Asymmetric sound field construction;

[0063] Signal interference principle: Two waves overlap in space, causing some areas to vibrate stronger and some areas to vibrate weaker. The phenomenon of a stable distribution of strengths and weaknesses in space is called wave interference. The necessary condition for two waves to interfere is that the two waves have the same frequency and a constant phase difference. Figure 2 As shown, loudspeaker #1 (-d / 2,0,0) and loudspeaker #2 (d / 2,0,0) are placed on the tunnel wall at an interval of d, emitting coherent signals with a frequency of f and a constant initial phase difference. The distance between the tunnel wall and one side of the auxiliary transport equipment is D, and the microphone deployed on the auxiliary transport equipment moves with the auxiliary transport equipment in the x-axis direction. When the microphone P is at a certain position (x,0,D), its distance to loudspeaker #1 and loudspeaker #2 are r1 and r2 respectively, then the combined amplitude of point P is the superposition of the amplitudes of the two sound sources at this position. When the path difference Δr is an even multiple of half the wavelength, the constructive interference amplitude at point P is enhanced, and bright stripes appear; when the path difference Δr is an odd multiple of half the wavelength, the destructive interference amplitude at point P is weakened, and dark stripes appear, that is:

[0064] When , point P is the center of the k-level bright fringe;

[0065] When , point P is the center of the k-level dark fringe.

[0066] in,

[0067] The equation satisfied by the k-level bright fringe is:

[0068] Arranged:

[0069] For the y=0 line, the coordinates of the center of the kth level bright fringe are (x Lk ,0,D), the coordinates of the center of the k-th dark pattern are (x Dk ,0,D), then

[0070] Since d>>kλ, D>>d, the above formula can be approximated as The distance between two adjacent bright (dark) stripes is Where c is the propagation speed of sound waves in the air. It can be seen that the interference fringe spacing Δx decreases with the increase of frequency f and sound source spacing d, and increases with the increase of the distance D from the sound source to the target plane.

[0071] The specific process of constructing an asymmetric sound field is as follows:

[0072] S21: Select the OFDM signal as the transmission signal of the two speakers, and use the ZC sequence to modulate the signal in the frequency domain to generate an interference sound field composed of superposition of different frequency components;

[0073] Since OFDM signals allow multiple frequency signals to be transmitted simultaneously, the transmitted signals of the two speakers will generate an interference sound field composed of superposition of different frequency components;

[0074] S22: In order to avoid the reduction of positioning accuracy due to the symmetry of the interference sound field, the OFDM signal is phase modulated; when the initial phases of the two subcarriers are the same, the interference sound field generated is symmetric about the x-axis, which will cause spatial blur and reduce the RSS positioning accuracy. When a non-zero initial phase difference is modulated for each subcarrier pair, the sound field shifts on the x-axis, and the initial phase difference is different, and the subcarrier pair has different translation amounts. A unique initial phase difference is set for each subcarrier so that the interference sound field generated by each subcarrier pair shifts to varying degrees in the x-axis direction to break the symmetry of the overall sound field and ensure that the RSS features at different positions are sufficiently different. This effectively reduces confusion in fingerprint matching and greatly improves matching accuracy.

[0075] S23: Since the loudspeaker has different responses to signals of different frequencies, the accuracy of the interference sound field may be affected. Therefore, the signal is subjected to frequency response equalization processing to ensure the stability of the interference sound field. First, the compensation factor set H(n) is calculated according to formula (1), and then the gain is adjusted according to the compensation factor set H(n) to match the target frequency response. Then, the OFDM baseband signal is extended to the required frame length by frequency domain interpolation to generate a time domain signal, and the target sound field signal is generated by inverse Fourier transform to ensure that the interference sound field has good spatial diversity and position differentiation ability, so as to generate a stable interference sound field with high RSS spatial uniqueness in the target area.

[0076]

[0077] Where n = 0, 1, ..., N ZC -1;Q target(n) is the target flat frequency response curve, Q(n) is the frequency response curve of the loudspeaker;

[0078] After frequency response equalization and phase modulation, the interference sound field has good spatial diversity and position distinction capabilities.

[0079] Step 3: Offline RSS collection;

[0080] Preset multiple candidate positioning points in the auxiliary transport operation area, use the acoustic wave receiver to collect RSS data at the multiple candidate positioning points in turn, and record the RSS data of each candidate positioning point;

[0081] Step 4: Generate gradient fingerprint image;

[0082] S41: After receiving the RSS data, the acoustic wave receiver performs demodulation to extract the interference intensity information of each subcarrier; specifically, when N sampling points are obtained after t time, and the frame length is set to N a When , the N sampling points are reconstructed into a size of The matrix Γ of

[0083]

[0084] S42: Each column of the matrix Γ represents a frame of received time domain signal, and its length is N a ,In order to analyze the frequency components of each frame signal, a fast Fourier transform is performed on each column of the matrix Γ to convert the time domain signal into frequency domain information; the interference intensity of each frequency component is obtained by extracting the frequency points corresponding to the preset frequency in the frequency domain signal; a multidimensional RSS fingerprint vector is constructed according to the received interference intensity;

[0085] S43: In order to make full use of the gradient changes within the vector, a gradient fingerprint image is constructed based on the multi-dimensional RSS fingerprint vector;

[0086] Subcarriers with different frequencies and initial phase differences will form a superposition of interference fringes with different periods and offsets. And because the peaks and troughs of the interference fringes are complex and intertwined, the interference signal intensity of each frequency component changes frequently in relative spatial position, thereby forming a significant gradient change. In order to intuitively present this change, the present invention converts the multidimensional RSS fingerprint vector into a two-dimensional gradient fingerprint image. Specifically, on a two-dimensional plane, the frequency index is used as the horizontal coordinate and the interference signal intensity is used as the vertical coordinate to draw the points corresponding to each frequency component, and connect these points in sequence to form a gradient fingerprint image; the rise or fall of the lines in the fingerprint image directly reflects the degree of change in the signal intensity between adjacent frequencies. Although the change in transmission power will affect the interference intensity of each frequency component, the relative intensity relationship between frequency components is relatively stable. As a form of spatial relative characteristics, the gradient fingerprint image mainly focuses on the relative changes within the fingerprint, so it is more capable of resisting time fluctuations.

[0087] Step 5: Establish a fingerprint library in the positioning area; divide the target area into discrete location spaces Form a candidate point grid, where N l is the number of candidate points; for each candidate point l σ (x σ ,y σ ), where 1≤σ≤N l , collect N f The interference strength of the subcarrier pairs is calculated and the RSS fingerprint vector is constructed. Among them, r σ,j Indicates that the jth subcarrier pair is at position l σ The interference intensity is taken as the subcarrier index j, and the interference intensity r σ,j As the ordinate, construct a gradient fingerprint image g for each position σ ={ <j,r σ,j >}, and finally form the fingerprint image library of the entire position space L

[0088] Step 6: Real-time fingerprint matching;

[0089] S61: Online RSS collection: When the auxiliary transportation equipment is running, the two speakers are synchronously controlled to send signals. At the same time, the microphone is used to receive RSS data in real time, and the real-time received RSS data is converted into a real-time fingerprint vector according to formula (3) to obtain the RSS vector R of the current point to be located. test ;

[0090] R test =[r test,1 ,r test ,2,…,r test,n ] (3);

[0091] S62: Convert the real-time fingerprint vector into the corresponding gradient fingerprint image g to be matched test ;

[0092] S63: Perform fingerprint matching using a fingerprint image matching algorithm based on discrete Frechet distance;

[0093] Fingerprint image is different from traditional RSS fingerprint, which reflects the spatial characteristics of relative changes within the vector. Although Euclidean distance is widely used in the similarity measurement of traditional RSS fingerprints, it is insensitive to the relative changes within the vector. Therefore, the present invention proposes a fingerprint image matching algorithm based on discrete Frechet distance. Frechet distance is usually used to measure the similarity of two curves, taking into account the shape and order of the curves, and can capture the relative changes of fingerprint vectors. The Frechet distance can be likened to the "dog walking distance": a person and a dog walk along two curves respectively and cannot go back, and the shortest leash length is the Frechet distance.

[0094] Based on the fingerprint image library G, the gradient fingerprint image g is obtained according to formula (4): test Frechet distance D F ; For each candidate point l in the fingerprint database σ ∈L fingerprint image g σ , according to formula (5), calculate its gradient fingerprint image g to be matched test The similarity d F (g test ,g σ ), select the candidate point corresponding to the fingerprint image with the smallest similarity as the target position l * , and output the target position l * As location information of auxiliary transportation equipment;

[0095]

[0096] In the formula, g i is a candidate fingerprint image, which comes from the fingerprint image library G; α(t) and β(t) are two increasing mapping functions; ∥·∥ is the Euclidean distance;

[0097] Step 7: Digital twin integration; The core of the digital twin system is to synchronize the real-time location information of coal mine auxiliary transportation equipment with the virtual model, so as to achieve accurate correspondence between physical equipment and virtual environment.

[0098] S71: Establish a communication connection between the edge computing node and the digital twin system;

[0099] S71: Data transmission and virtualization stage; after the edge computing node obtains the location data of the auxiliary transportation equipment in real time, it transmits the location data to the digital twin system through the wireless communication network. The digital twin system generates a virtual model of the auxiliary transportation equipment based on the real-time location data, and dynamically displays the virtual model in the pre-built three-dimensional model of the mine environment. At the same time, it is displayed in real time through the display screen to dynamically reflect the location and operating status of the auxiliary transportation equipment in the mine.

[0100] S72: Real-time monitoring and optimization stage; through the digital twin system, the status, location and trajectory of the auxiliary transportation equipment are monitored in real time, and virtual modeling and precise tracking of the operating status of the auxiliary transportation equipment are achieved, providing data support for production scheduling optimization and equipment health management.

[0101] As a preferred embodiment, in S71 of step seven, the digital twin system continuously updates the position of the virtual model of the auxiliary transportation equipment according to a set time interval to ensure that the position of the virtual model of the auxiliary transportation equipment is highly consistent with the actual limit position of the auxiliary transportation equipment.

[0102] As a preferred embodiment, in step 2 S21, the length N is obtained by formula (6) ZC The ZC sequence zc[n];

[0103]

[0104] In the formula, u and q are sequence parameters, and u and N ZC Being mutually prime ensures that the ZC sequence has good autocorrelation characteristics, and i is the imaginary unit.

[0105] In the present invention, two loudspeakers are first controlled to generate coherent sound waves, forming an interference sound field with alternating strengths and weaknesses in space. At the same time, OFDM signals are selected as the transmission signals of the two loudspeakers located on the tunnel wall, and the baseband signals are phase modulated and frequency-response balanced, which can generate a stable asymmetric interference sound field with high RSS spatial diversity in the target area. In this way, it can be ensured that in a complex mine tunnel environment, when the auxiliary transportation equipment is in different positions, the intensity of the signal received by the microphone deployed thereon can form a unique RSS distribution with the change of position, thereby providing a reliable basis for the subsequent positioning process. The construction of the RSS fingerprint library in advance in the offline process is conducive to the rapid and accurate matching of the target position of the auxiliary transportation equipment through the Frechet distance algorithm when the RSS data is obtained in real time in the subsequent process. By combining the fingerprint library with the matching algorithm of the Frechet distance, accurate position estimation can be achieved, and centimeter-level positioning accuracy can still be provided even in a complex mine or tunnel environment. After obtaining the real-time position data, a virtual model of the auxiliary transportation equipment is constructed through the digital twin system, and displayed in real time in the pre-built three-dimensional module of the mine environment. In this way, the real-time position information of the auxiliary transportation equipment in the coal mine can be synchronized with the virtual model using the digital twin system, thereby achieving accurate correspondence between the physical equipment and the virtual environment. In the digital twin system, the position of the virtual auxiliary transportation equipment changes synchronously with the physical auxiliary transportation equipment. The system will adjust the position, direction and movement trajectory of the auxiliary transportation equipment in the virtual environment in real time, which can facilitate relevant personnel to monitor the operating status, current position and travel path of the auxiliary transportation equipment in real time on the visual interface, and can provide technical support for production scheduling optimization and equipment health management.

[0106] This method overcomes the limitations of existing coal mine positioning technology. It can not only quickly and accurately realize the positioning of auxiliary transportation equipment in complex coal mine environments, but also improve the safety and efficiency of mine operations through real-time feedback and visual monitoring. It helps managers to accurately control the operating status of coal mine auxiliary transportation equipment, significantly reduce the failure rate, and improve the safety factor of operations.

Claims

1. An acoustic wave positioning device for a coal mine auxiliary transportation digital twin system, comprising an acoustic wave transmitter, characterized in that: It also includes a controller, an acoustic wave receiver, and an edge computing node; The sound wave transmitter is two loudspeakers, which are installed on the side wall of the lane in the operation area of ​​the auxiliary transportation equipment at a set distance, and are used to continuously emit sound wave signals and generate an interference sound field composed of superimposed different frequency components; The controller is connected to the sound wave transmitter and is used to control the action of the sound wave transmitter; The sound wave receiver is an omnidirectional microphone, which is installed on the auxiliary transportation equipment and is used to receive the sound wave signal and send the sound wave signal to the edge computing node; The edge computing node is installed on the auxiliary transportation equipment and connected to the sound wave receiver, so as to analyze and process the sound wave signal and obtain the location information of the auxiliary transportation equipment based on the processed sound wave signal.

2. The acoustic wave positioning device for the coal mine auxiliary transportation digital twin system according to claim 1 is characterized in that: It also includes a display, which is connected to the edge computing node and is used to display the location information sent by the edge computing node in real time.

3. A sonic positioning method for a coal mine auxiliary transportation digital twin system, using a sonic positioning device for a coal mine auxiliary transportation digital twin system as claimed in any one of claims 1 or 2, characterized in that: The following steps are involved: Step 1: Install the sonar positioning device; Install two speakers at a set distance on the side wall of the lane in the auxiliary transportation equipment operation area, and ensure that the sound wave signals emitted by the two speakers can cover the auxiliary equipment operation area; install edge computing nodes and sound wave receivers on the auxiliary transportation equipment, and establish a communication connection between the edge computing nodes and the sound wave receivers; Step 2: Asymmetric sound field construction; S21: Select the OFDM signal as the transmission signal of the two speakers, and use the ZC sequence to modulate the signal in the frequency domain to generate an interference sound field composed of superposition of different frequency components; S22: Phase modulate the OFDM signal; set a unique initial phase difference for each subcarrier so that the interference sound field generated by each subcarrier pair is translated to different degrees in the x-axis direction to break the symmetry of the overall sound field and ensure that the RSS features at different positions have sufficient differences; S23: Perform frequency response equalization processing on the signal to ensure the stability of the interference sound field; first calculate the compensation factor set H(n) according to formula (1), and then adjust the gain according to the compensation factor set H(n) to match the target frequency response; then, extend the OFDM baseband signal to the required frame length through frequency domain interpolation to generate a time domain signal, and generate a target sound field signal through inverse Fourier transform to ensure that the interference sound field has good spatial diversity and position differentiation ability, so as to generate a stable interference sound field with high RSS spatial uniqueness in the target area; Where n = 0, 1, ..., N ZC -1;Q target (n) is the target flat frequency response curve, Q(n) is the frequency response curve of the loudspeaker; Step 3: Offline RSS collection; Preset multiple candidate positioning points in the auxiliary transport operation area, use acoustic wave receivers to collect RSS data at the multiple candidate positioning points in turn, and record the RSS data of each candidate positioning point; Step 4: Generate gradient fingerprint image; S41: After receiving the RSS data, the acoustic wave receiver demodulates to extract the interference intensity information of each subcarrier; when N sampling points are obtained after t time, and the frame length is set to N a When , the N sampling points are reconstructed into a size of The matrix Γ of S42: Performing a fast Fourier transform on each column of the matrix Γ to convert the time domain signal into frequency domain information; obtaining the interference intensity of each frequency component by extracting the frequency point corresponding to the preset frequency in the frequency domain signal; constructing a multidimensional RSS fingerprint vector according to the received interference intensity; S43: constructing a gradient fingerprint image based on the multi-dimensional RSS fingerprint vector; on a two-dimensional plane, using the frequency index as the horizontal coordinate and the interference signal intensity as the vertical coordinate, plotting the points corresponding to each frequency component, and connecting these points in sequence to form a gradient fingerprint image; Step 5: Establish a fingerprint library in the positioning area; divide the target area into discrete location spaces Form a candidate point grid, where N l is the number of candidate points; for each candidate point l σ (x σ ,y σ ), where 1≤σ≤N l , collect N f The interference strength of the subcarrier pairs is calculated and the RSS fingerprint vector is constructed. Among them, r σ,j Indicates that the jth subcarrier pair is at position l σ The interference intensity is taken as the subcarrier index j, and the interference intensity r σ,j As the ordinate, construct a gradient fingerprint image g for each position σ ={ <j,r σ,j >}, and finally form the fingerprint image library of the entire position space L Step 6: Real-time fingerprint matching; S61: Online RSS collection: When the auxiliary transportation equipment is running, the two speakers are synchronously controlled to send signals. At the same time, the microphone is used to receive RSS data in real time, and the real-time received RSS data is converted into a real-time fingerprint vector according to formula (3) to obtain the RSS vector R of the current point to be located. test ; R test ＝[r test,1 ,r test ,2,…,r test,n ] (3)； S62: Convert the real-time fingerprint vector into the corresponding gradient fingerprint image g to be matched test ; S63: Perform fingerprint matching using a fingerprint image matching algorithm based on discrete Frechet distance; obtain a gradient fingerprint image g based on the fingerprint image library G according to formula (4) test Frechet distance D F ; For each candidate point l in the fingerprint database σ ∈L fingerprint image g σ , according to formula (5), calculate its gradient fingerprint image g to be matched test The similarity d F (g test ,g σ ), select the candidate point corresponding to the fingerprint image with the smallest similarity as the target position l * , and output the target position l * As location information of auxiliary transportation equipment; In the formula, g i is a candidate fingerprint image, which comes from the fingerprint image library G; α(t) and β(t) are two increasing mapping functions; ∥·∥ is the Euclidean distance; Step 7: Digital twin integration; S71: Establish a communication connection between the edge computing node and the digital twin system; S71: Data transmission and virtualization stage; after the edge computing node obtains the location data of the auxiliary transportation equipment in real time, it transmits the location data to the digital twin system through the wireless communication network. The digital twin system generates a virtual model of the auxiliary transportation equipment based on the real-time location data, and dynamically displays the virtual model in the pre-built three-dimensional model of the mine environment. At the same time, it is displayed in real time through the display screen to dynamically reflect the location and operating status of the auxiliary transportation equipment in the mine. S72: Real-time monitoring and optimization stage; through the digital twin system, the status, location and trajectory of the auxiliary transportation equipment are monitored in real time, and virtual modeling and precise tracking of the operating status of the auxiliary transportation equipment are achieved, providing data support for production scheduling optimization and equipment health management.

4. The acoustic wave positioning method for the coal mine auxiliary transportation digital twin system according to claim 3 is characterized in that: In step seven S71, the digital twin system continuously updates the position of the virtual model of the auxiliary transportation equipment according to a set time interval to ensure that the position of the virtual model of the auxiliary transportation equipment is highly consistent with the actual limit position of the auxiliary transportation equipment.

5. The acoustic wave positioning method for the digital twin system of coal mine auxiliary transportation according to claim 4 is characterized in that: In step 2 S21, the length N is obtained by formula (6) ZC The ZC sequence zc[n]; In the formula, u and q are sequence parameters, and u and N ZC Being mutually prime ensures that the ZC sequence has good autocorrelation characteristics, and i is the imaginary unit.

6. The acoustic wave positioning method for the digital twin system of coal mine auxiliary transportation according to claim 4 is characterized in that: In step seven S72, when the digital twin system detects that the position of the auxiliary transportation equipment is abnormal or the positioning data is abnormal, it sends a warning message to the display screen and, at the same time, controls the alarm device connected to it to give an audible and visual alarm.

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