A coal mine underground positioning method and system based on UWB

Abstract

The application provides a coal mine underground positioning method and system based on UWB, and the application forms a whole-process collaborative verification and dynamic adaptation mechanism by establishing a multi-dimensional multipath feature database, generating a standardized feature label, screening high-quality second base stations and dynamically adjusting the number of the high-quality second base stations, constructing a joint confidence model based on time delay-amplitude-phase to determine path accessibility, and eliminating invalid paths in combination with multi-base station consensus decision, so that the problems of disordered multipath data management, weak anti-interference ability of a single base station, high path determination misjudgment rate, low UWB positioning precision caused by invalid multipath persistent interference positioning calculation, and poor adaptability of the prior art in a complex multi-reflection environment in a coal mine are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of downhole positioning, in particular to a coal mine downhole positioning method and system based on UWB. BACKGROUND

[0002] Due to the strong reflection characteristics of metal materials on UWB signals, the signals are prone to multiple reflections, refractions and scattering during propagation, thereby forming a very complex multipath propagation environment. On the one hand, the ranging value will fluctuate violently and irregularly, and the fluctuation range often exceeds ±1 meter, resulting in a significant decrease in the positioning result accuracy based on distance measurement, which is difficult to meet the basic requirements of positioning accuracy in actual applications. On the other hand, when processing these multipath signals, the positioning engine often incorrectly determines the reflection path with strong energy as the direct path, further exacerbating the positioning deviation, and even giving positioning information completely inconsistent with the actual position. In the face of this technical problem, the existing solutions have the following shortcomings: conventional multipath suppression algorithms, such as methods relying on first-path detection, are greatly weakened or even completely ineffective in this kind of strong reflection environment, because the first-path signal may be obscured or interfered by the reflected signal; and attempts to improve the positioning effect by increasing the base station density are also restricted by the signal shielding problem caused by dense on-site devices and the strict intrinsic safety requirements in industrial scenarios, making it difficult to effectively implement in practice. SUMMARY

[0003] Based on the technical problems existing in the above background technology, the present application proposes a coal mine downhole positioning method and system based on UWB, and the solutions adopted include:

[0004] A coal mine downhole positioning method based on UWB, the method comprising:

[0005] S1: Each base station analyzes the tag signal and records the characteristic parameters of the multipath components, including signal arrival time, signal amplitude and signal phase, and generates a characteristic tag containing the characteristic parameters for each path, and establishes a local multipath characteristic database;

[0006] S2: The first base station receives the tag signal, and when the first base station detects multiple paths of the same tag signal, sends a data request to the nearby second base station to obtain the characteristic parameters of the multipath components of the same tag signal received by the second base station at the same time;

[0007] S3: Reachability determination of multiple paths of the first base station: through the cooperative verification of the second base station on whether there is a shorter time delay path, whether the signal amplitude attenuation conforms to the reflection characteristics, and whether the signal phase jump matches the dynamic reflection scene, the reachability determination of multiple paths is realized;

[0008] S4: According to the path reachability determination result fed back by the second base station, the proportion of base stations determined as unreachable paths is counted, and when the proportion of base stations exceeds a preset threshold, the corresponding path is excluded from the positioning calculation.

[0009] Preferably, the S1 includes specifically:

[0010] The multipath components of the same tag signal are sorted by the time stamp of reception to establish a time sequence index.

[0011] A unique path identifier is generated for each path.

[0012] Preferably, the S1 includes specifically:

[0013] The signal amplitude is converted into a normalized value.

[0014] The signal phase is subjected to cyclic redundancy check.

[0015] A feature vector containing the normalized value of the signal amplitude, the phase signal subjected to cyclic redundancy check, and the signal arrival time is generated.

[0016] Preferably, the S2 includes specifically:

[0017] The first base station is taken as the center to define a screening radius, and all base stations within the screening radius are preliminarily screened as candidate base stations.

[0018] Real-time link assessment is performed on the candidate base stations, and the assessment indicators include the signal-to-noise ratio, bit error rate, multipath delay spread, and clock synchronization deviation of each candidate base station; when the assessment indicators all meet the preset threshold of real-time link assessment, the candidate base station is screened as the second base station.

[0019] Preferably, the number of second base stations is dynamically adjusted according to the metal equipment density in the coal mine, and specifically includes:

[0020] The coal mine is divided into a complex scene with dense equipment and a simple scene with open space through the number of multipath components.

[0021] For the complex scene, the number of screened second base stations is increased.

[0022] For the simple scene, the number of screened second base stations is reduced.

[0023] If the number of screened second base stations does not meet the preset minimum number requirement, the screening radius is gradually expanded until the number of screened second base stations meets the preset minimum number requirement.

[0024] Preferably, the S3 includes specifically:

[0025] retrieve time delay parameters of the plurality of paths from a local multipath characteristic database of the first base station, the time delay parameter = signal arrival time - signal transmission time, and predict a theoretical time delay parameter based on a spatial position of the first base station and the tag signal;

[0026] if the time delay of the i-th path of the first base station is greater than the theoretical time delay parameter, traverse the time delay parameters of the second base stations, if the time delay of the j-th path of the second base station is less than the time delay of the i-th path of the first base station, mark the i-th path of the first base station as a suspected reflection path; if none of the second base stations has a path with a time delay less than the time delay of the i-th path of the first base station, mark the i-th path of the first base station as to be further verified;

[0027] count the number of paths of the second base stations whose time delays are less than the time delays of the paths of the first base station, and calculate a proportion of the total number of paths of the second base stations, and take the proportion as an input value in the time delay dimension.

[0028] Preferably, the to-be-further-verified specifically includes:

[0029] retrieve signal amplitude attenuation characteristics of the path to be further verified, and calculate a matching degree with a preset reflection propagation model, and generate a reflection probability score value based on the matching degree difference;

[0030] retrieve a phase change sequence of a signal cycle of the path to be further verified, identify a non-continuous jump feature, and generate a dynamic reflection probability score value according to the amplitude of the jump feature.

[0031] Preferably, the S3 specifically includes:

[0032] establish a dynamic constraint model related to the time delay parameter, the signal amplitude, and the signal phase;

[0033] generate a joint confidence score according to the weights;

[0034] when the joint confidence score exceeds a threshold value, determine that the path is unreachable.

[0035] Preferably, the S4 specifically includes:

[0036] the first base station collects independent reachability determination results of the same path by each second base station;

[0037] count the number of second base stations that determine that the path is unreachable, and calculate a proportion of the total number of second base stations participating in the determination;

[0038] when the proportion exceeds a preset threshold value, confirm that the path is a truly unreachable path, and permanently exclude this path from positioning calculation.

[0039] A coal mine underground positioning system based on UWB, the system comprises:

[0040] A multipath feature collection and filing system: each base station analyzes a tag signal and records characteristic parameters of multipath components, the characteristic parameters including signal arrival time, signal amplitude and signal phase, and generates a characteristic tag containing the characteristic parameters for each path, and establishes a local multipath feature database;

[0041] A cross-base station cooperative data interaction system: the first base station receives a tag signal, and when the first base station detects multiple paths of the same tag signal, sends a data request to a nearby second base station to obtain characteristic parameters of multipath components of the same tag signal received by the second base station at the same time;

[0042] A multi-dimensional path attribute verification system: the first base station performs reachability determination on multiple paths: through cooperative verification of the second base station on whether there is a shorter time delay path, whether the signal amplitude attenuation conforms to the reflection characteristics, and whether the signal phase jump matches the dynamic reflection scene, reachability determination on multiple paths is realized;

[0043] A path validity consensus decision system: according to the path reachability determination result fed back by the second base station, the proportion of base stations determined to be unreachable paths is counted, and when the proportion of base stations exceeds a preset threshold, the corresponding path is excluded from positioning calculation.

[0044] The present application has the following advantages: the present application establishes a multi-dimensional multipath feature database and generates a standardized characteristic tag, selects high-quality second base stations and dynamically adjusts the number of second base stations, constructs a joint confidence model based on time delay-amplitude-phase to determine path reachability, and excludes invalid paths through multi-base station consensus decision, forming a whole-process cooperative verification and dynamic adaptation mechanism, solving the problems of chaotic multipath data management in the prior art in a complex and multi-reflective environment in a coal mine, weak anti-interference ability of a single base station, high path determination misjudgment rate, and low UWB positioning precision and poor adaptability caused by invalid multipath continuous interference in positioning calculation. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 A coal mine underground positioning method based on UWB is described. DETAILED DESCRIPTION

[0046] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0047] An embodiment of the present application is a coal mine underground positioning method based on UWB, the method comprising:

[0048] S1: Each base station analyzes the tag signal, records the characteristic parameters of the multipath components, the characteristic parameters including signal arrival time, signal amplitude and signal phase, generates a characteristic tag containing the characteristic parameters for each path, and establishes a local multipath characteristic database;

[0049] S2: The first base station receives the tag signal, and when the first base station detects multiple paths of the same tag signal, sends a data request to a nearby second base station to obtain the characteristic parameters of the multipath components of the same tag signal received by the second base station at the same time;

[0050] S3: Reachability determination is performed on the multiple paths of the first base station: through the cooperative verification of the second base station on whether there is a shorter time delay path, whether the signal amplitude attenuation conforms to the reflection characteristics, and whether the signal phase jump matches the dynamic reflection scene, the reachability determination of the multiple paths is realized;

[0051] S4: According to the path reachability determination result fed back by the second base station, the proportion of base stations determined to be unreachable paths is counted, and when the proportion exceeds a preset threshold, the corresponding path is excluded from the positioning calculation.

[0052] The working principle and effect of the above technical solution are: through each base station analyzing the tag signal and recording the signal arrival time, amplitude, phase and other characteristic parameters of the multipath components, generating a characteristic tag and establishing a local multipath characteristic database, when the first base station detects multiple paths of the same tag signal, sends a data request to a nearby second base station to obtain the multipath characteristic parameters of the same tag signal received by the second base station at the same time, then through the cooperative verification of the second base station on whether there is a shorter time delay path, whether the signal amplitude attenuation conforms to the reflection characteristics and whether the signal phase jump matches the dynamic reflection scene, the reachability determination of the multiple paths of the first base station is performed, finally according to the determination result fed back by the second base station, the proportion of base stations determined to be unreachable paths is counted, when the proportion exceeds a preset threshold, the corresponding path is excluded from the positioning calculation, thereby realizing the positioning of the tag in the coal mine.

[0053] The method distinguishes between real direct paths and reflection interference paths, reduces the positioning error caused by the complex environment in the coal mine, and at the same time, through the consensus proportion of multiple base stations on the unreachability of the path and the setting of a dynamic threshold, avoids the loss of effective paths or the reservation of invalid paths caused by the misjudgment of a single base station, and improves the accuracy and reliability of the positioning result.

[0054] In an embodiment of the present application, the establishment of the local multipath characteristic database in S1 specifically includes:

[0055] The multipath components of the same tag signal are sorted according to the reception time stamp to establish a time sequence index;

[0056] A unique path identifier is generated for each path.

[0057] The working principle and effect of the above technical solution are that: after each base station analyzes the tag signal, the multipath components of the same tag signal are first sequentially arranged according to the receiving time stamp, so as to construct a time sequence index, so that the propagation time sequence relationship of the multipath components is clearly presented, and a unique path identifier is generated for each path, so as to realize accurate differentiation and marking of different paths.

[0058] By sequentially arranging the multipath components of the same tag signal according to the receiving time stamp to establish a time sequence index, the propagation time sequence relationship of the multipath components can be clearly presented, the time sequence confusion caused by disordered multipath signals is avoided, and the order of arrival of signals of different paths is quickly traced back, so as to provide an ordered data basis for analyzing the multipath propagation law; and a unique path identifier is generated for each path, so as to realize accurate differentiation and unique marking of different paths, and avoid confusion and misunderstanding between paths.

[0059] In an embodiment of the present application, the feature label generation mode of the S1 comprises:

[0060] Converting the signal amplitude into a normalized value;

[0061] Performing cyclic redundancy check on the signal phase;

[0062] Generating a feature vector containing the normalized value of the signal amplitude, the phase signal after cyclic redundancy check, and the signal arrival time.

[0063] The working principle and effect of the above technical solution are that: first, the received signal amplitude is normalized, the actual amplitude value is mapped to a fixed range (0-1), the amplitude value deviation caused by the difference in transmission power of different tags or the difference in propagation distance is eliminated, and the amplitude feature has a unified comparison reference; at the same time, cyclic redundancy check (CRC) is performed on the signal phase, the integrity of the phase data is detected by a preset check algorithm, the effective phase information that is not tampered by noise or interference is screened out, and the phase data with transmission error is eliminated; finally, the normalized amplitude value, the phase signal that passes the check, and the signal arrival time, which are three kinds of core feature parameters, are integrated to construct a feature vector containing multi-dimensional information, which is used as the unique feature label of each path.

[0064] The signal amplitude is converted into a normalized value, which can eliminate the amplitude value deviation caused by different tag transmission power differences or propagation distances, make the amplitude characteristics have a unified comparison reference, and avoid feature misjudgment caused by original amplitude value differences; the signal phase is subjected to cyclic redundancy check, which can effectively filter out effective phase information that is not tampered with by noise or interference, and eliminate phase data with transmission errors, thereby ensuring the reliability of the phase characteristics; the feature vector including the amplitude normalized value, the checked phase signal and the signal arrival time is generated, which can realize the standardization and multi-dimensional accurate description of the multipath component characteristics, provide consistent and reliable basic data for the establishment of a multipath feature database, facilitate subsequent rapid path identification and cross-path comparison, improve the accuracy and efficiency of multipath feature matching, and reduce positioning errors caused by inconsistent feature descriptions or invalid data.

[0065] In one embodiment of the application, the second base station S2 is screened by the following method:

[0066] A screening radius is defined with the first base station as the center, and all base stations within the screening radius are preliminarily screened as candidate base stations.

[0067] Real-time link evaluation is performed on the candidate base stations, and the evaluation indexes include the signal-to-noise ratio, bit error rate, multipath time delay spread and clock synchronization deviation of each candidate base station; when the evaluation indexes all meet the preset threshold values of the real-time link evaluation, the candidate base stations are screened as the second base station.

[0068] The working principle and effects of the above technical solution are as follows: first, a screening radius (50-100 meters) is defined with the first base station as the center, and all base stations within the radius are preliminarily screened as candidate base stations; then, real-time link evaluation is performed on the candidate base stations, and the evaluation indexes and preset threshold values include: the signal-to-noise ratio needs to be greater than or equal to 15 dB, the bit error rate needs to be less than or equal to 10 -6 ns, the multipath time delay spread needs to be less than or equal to 50 ns, and the clock synchronization deviation needs to be less than or equal to 10 ns; when the above evaluation indexes of the candidate base stations all meet the corresponding threshold values, the candidate base stations are screened as the second base station.

[0069] The screening radius is defined with the first base station as the center to preliminarily screen the candidate base stations, which quickly reduces the range and reduces the calculation amount of subsequent evaluation, while ensuring that the spatial distance between the candidate base stations and the first base station is within a reasonable range, avoiding the problem of excessive signal attenuation or cooperative delay caused by too far distance; real-time link evaluation is performed on the candidate base stations, including the signal-to-noise ratio, bit error rate, multipath time delay spread and clock synchronization deviation, and clear threshold values are set, which can improve the accuracy of screening the base stations with good signal quality, reliable data transmission, small multipath interference and consistent time reference as the second base station, and avoid cooperative positioning errors caused by insufficient base station performance

[0070] One embodiment of the present application, the number of second base stations is dynamically adjusted according to the metal equipment density in the coal mine, specifically comprising:

[0071] The coal mine is divided into equipment-intensive complex scene and space-open simple scene by the number of multipath components;

[0072] For complex scene, increase the number of second base station screening;

[0073] For simple scene, reduce the number of second base station screening;

[0074] If the number of screened second base stations does not reach the preset minimum number requirement, gradually expand the screening radius until the number of screened second base stations meets the preset minimum number requirement.

[0075] The working principle and effect of the above technical solution are: by counting the number of multipath components received in a unit of time to divide the scene, when the number of multipath components is ≥20 per second, it is determined as an equipment-intensive complex scene; when the number of multipath components is <10 per second, it is determined as a space-open simple scene; for complex scene, the number of second base station screening is preset to 5-8 to enhance the multi-base station cooperative anti-interference ability; for simple scene, the screening number is preset to 2-3 to reduce resource occupation; At the same time, the preset minimum number requirement is set to 2, if the number of initially screened second base stations does not reach the requirement, the screening radius is gradually expanded by 5 meters as a step (maximally expanded to twice the initial radius), until the number of screened second base stations meets the minimum requirement.

[0076] By dividing the complex scene and simple scene by the number of multipath components, and dynamically adjusting the number of second base stations, increasing the number of second base station screening in the equipment-intensive complex scene can enhance the multi-base station cooperative anti-interference ability, improve the adaptability to multi-reflection environment, and avoid the decline of positioning accuracy caused by insufficient number of base stations; reducing the number of second base stations in the space-open simple scene can reduce resource occupation and avoid unnecessary computing power and communication consumption; while ensuring positioning accuracy and reliability, resource optimization is realized, and the adaptability and efficiency of the coal mine positioning system in different scenes are improved.

[0077] One embodiment of the present application, the S3 specifically comprises:

[0078] Retrieve the delay parameters of multiple paths from the local multipath characteristic database of the first base station, the delay parameter = signal arrival time-signal transmission time, and predict the theoretical delay parameter based on the spatial position of the first base station and the tag signal;

[0079] If the time delay of the i-th path of the first base station is greater than the theoretical time delay parameter, the time delay parameter of the second base station is traversed, if the time delay of the j-th path of the second base station is less than the time delay of the i-th path of the first base station, the i-th path of the first base station is determined as a suspected reflection path; if the second base station does not have a path less than the time delay of the i-th path of the first base station, the i-th path of the first base station is determined as to be further verified;

[0080] The number of paths of the second base station whose time delay is less than that of the path of the first base station is counted, and the proportion of the total number of paths of the second base station is calculated, which is used as an input value in the time delay dimension.

[0081] The working principle and effect of the above technical solution are:

[0082] In one embodiment of the present application, the to-be-further-verified specifically includes:

[0083] The signal amplitude attenuation characteristics of the path to be further verified are retrieved, and a matching degree is calculated with a preset reflection propagation model, a reflection probability score value is generated based on the matching degree difference, the reflection probability score value is used as an input value in the signal amplitude dimension, and the reflection probability score value is obtained by the following formula:

[0084]

[0085] Wherein, D represents the reflection probability score value, A0 represents the theoretical amplitude value obtained by the preset reflection model, A1 represents the actual signal amplitude value of the path to be further verified, K represents the environmental correction coefficient, and K=1+0.02*P, wherein P represents the metal equipment density, and the theoretical amplitude value obtained by the preset reflection model is obtained by the following formula:

[0086] A0=A f -α×5log 10 (d)-n×L r

[0087] Wherein, A f represents the theoretical signal amplitude value calculated based on the free space propagation model, represents the amplitude attenuation characteristics of the signal when propagating in the ideal free space without shielding and reflection, alpha represents the roadway cross section correction coefficient (alpha=1.2±0.1, based on the measured value of UWB signal attenuation in different cross section roadways in the "Coal Mine Underground Wireless Communication Technical Specification"), d represents the path propagation distance, d= time delay parameter*light speed, n represents the number of single reflection losses (metal equipment reflection loss is 15±5dB) in the propagation process from the tag to the first base station, and L r represents the single reflection loss (metal equipment reflection loss is 15±5dB), and the theoretical signal amplitude value Af The phase change sequence of the signal period of the path to be further verified is obtained by the following formula:

[0088] A f = A-20log 10 (d)

[0089] The phase change sequence of the signal period of the path to be further verified is identified, the non-continuous jump feature is identified, the dynamic reflection probability score value is generated according to the amplitude of the jump feature, and the reflection probability score value is taken as the input value of the signal phase dimension, and the reflection probability score value is obtained by the following formula:

[0090]

[0091] Wherein, M represents the number of times that the phase jump amplitude exceeds the normal fluctuation range of the direct path in the continuous sampling period, and S represents the total number of sampling periods.

[0092] The working principle and effect of the above technical solution are: in the calculation formula of the above reflection probability score value, the basic law of free space propagation is combined with the unique roadway structure constraint and the strong reflection of metal equipment in the mine to form an actual reflection path amplitude model, alpha times 5log 10 (d) Quantify the additional attenuation of the roadway structure to the signal: the mine roadway is a closed rectangular space, and the signal will be additionally lost due to the absorption and scattering of the roadway wall (coal, rock), and the loss will increase logarithmically with the increase of distance, alpha is adapted to different section sizes (such as slower attenuation in large section roadway), so that the model can reflect the physical characteristics that "the narrower the roadway, the farther the distance, the more significant the attenuation"; -n x L r Quantify the cumulative loss of metal equipment reflection: there are a large number of metal equipment (hydraulic support, scraper, etc.) in the coal mine, and each metal reflection of the signal will produce a fixed loss, and the more the number of reflections, the greater the total loss.

[0093] The formula converts the unique narrow roadway section, dense metal equipment and other physical characteristics in the coal mine into quantifiable parameters, avoids the misjudgment of the reflection path caused by the general model ignoring the characteristics of the mine scene, solves the problem that the traditional single factor correction cannot cope with the complex multi-reflection environment in the mine, and reduces the demand for base station computing power through the simplified calculation logic without complex weights, and adapts to low-power devices in the mine; This design can accurately capture the attenuation characteristics and environmental fluctuations of multi-reflection superposition, improve the identification accuracy of the direct path in the equipment dense area, improve the positioning stability when the equipment moves, and speed up the identification speed of dynamic reflection.

[0094] In one embodiment of the present application, the implementation of S3 determines the reachability of multiple paths, specifically including:

[0095] A dynamic constraint model related to the delay parameter, signal amplitude and signal phase is established;

[0096] generating a joint confidence score according to the weights;

[0097] determining that the path is unreachable when the joint confidence score exceeds a threshold.

[0098] The working principle and effects of the above technical solution are as follows: firstly, a dynamic constraint model containing a time delay parameter, a signal amplitude, and a signal phase is established, wherein the time delay parameter constraint is that the deviation of the measured time delay from the theoretical propagation time delay needs to be ≤50ns, the signal amplitude constraint is that the relative deviation of the actual received amplitude from the model predicted amplitude needs to be ≤15%, and the signal phase constraint is that the phase jump amplitude of adjacent periods needs to be ≤π / 2; then, weights are assigned to the three constraint dimensions (the time delay parameter weight is 0.4, the signal amplitude weight is 0.3, and the signal phase weight is 0.3), the deviation values of each dimension are standardized (the smaller the deviation, the higher the score, and the range is 0-1), a joint confidence score (the total score range is 0-1) is generated by weighted summation; the joint confidence score threshold is set to 0.6, and when the calculated joint confidence score is ≤0.6, it is determined that the path is unreachable (i.e., it does not conform to the normal propagation rule, and it is an invalid multipath), otherwise it is determined to be a reachable path.

[0099] The physical propagation possibility of the path is verified from multiple dimensions to avoid misjudgment caused by single parameter determination; the constraint conditions of time delay deviation ≤50ns, amplitude relative deviation ≤15%, and phase jump ≤π / 2 frame the characteristic range of the normal propagation path, improve the rigor of the reachability determination; when the joint confidence score is ≤0.6, it is determined that the path is unreachable, which can effectively filter out invalid multipaths that do not conform to the propagation rule, reduce the interference of invalid paths on subsequent positioning calculation, and improve the reliability of the positioning result.

[0100] In an embodiment of the present application, the S4 specifically comprises:

[0101] The first base station collects independent reachability determination results of the same path by each second base station;

[0102] The number of second base stations that determine that the path is unreachable is counted, and the proportion of the number in the total number of second base stations participating in the determination is calculated;

[0103] When the proportion exceeds a preset threshold, it is confirmed that the path is a truly unreachable path, and the path is permanently excluded from the positioning calculation.

[0104] The working principle and effects of the above technical solution are as follows: the first base station first collects independent reachability determination results of each second base station for the same path; then, the number of second base stations determining that the path is unreachable is counted, and the proportion of the number in the total number of second base stations participating in determination is calculated; the preset threshold is set to 50%, when the calculated proportion exceeds 50%, it is confirmed that the path is a real unreachable path, and it is permanently excluded from the positioning calculation and is no longer used as a reference basis for subsequent positioning.

[0105] Avoids the misjudgment of a single base station caused by local environmental interference, ensures that the excluded path is a real unreachable path confirmed by a majority of base stations, reduces the continuous interference of invalid paths on positioning calculation, and at the same time, the permanent exclusion processing mode reduces the algorithm power consumption of repeated determination in subsequent calculation, and improves the operation efficiency of the positioning system.

[0106] One embodiment of the present application is a coal mine underground positioning system based on UWB, the system comprises:

[0107] A multipath feature acquisition and filing system: each base station analyzes the tag signal and records the characteristic parameters of the multipath component, the characteristic parameters include signal arrival time, signal amplitude and signal phase, and generates a characteristic tag containing characteristic parameters for each path, and establishes a local multipath feature database;

[0108] A cross-base station cooperative data interaction system: the first base station receives the tag signal, when the first base station detects multiple paths of the same tag signal, sends a data request to the nearby second base station, and obtains the characteristic parameters of the multipath component of the same tag signal received by the second base station at the same time;

[0109] A multi-dimensional path attribute verification system: the reachability of multiple paths of the first base station is determined: through the cooperative verification of the second base station on whether there is a shorter time delay path, whether the signal amplitude attenuation conforms to the reflection characteristics, and whether the detection signal phase jump matches the dynamic reflection scene, the reachability of multiple paths is determined;

[0110] A path validity consensus decision system: according to the path reachability determination result fed back by the second base station, the proportion of base stations determined as unreachable paths is counted, when the proportion of base stations exceeds the preset threshold, the corresponding path is excluded from the positioning calculation.

[0111] The working principle and effects of the above technical solution are as follows: the base stations analyze the tag signals and record the signal arrival time, amplitude, phase and other characteristic parameters of the multipath components to generate characteristic tags and establish a local multipath characteristic database; when the first base station detects that there are multiple paths for the same tag signal, it sends a data request to the nearby second base station to obtain the multipath characteristic parameters of the tag signal received by the second base station at the same time; then, through the cooperative verification of the second base station on whether there is a shorter time delay path, whether the signal amplitude attenuation conforms to the reflection characteristics, and whether the signal phase jump matches the dynamic reflection scene, the reachability of the multiple paths of the first base station is determined; finally, according to the determination result fed back by the second base station, the proportion of the base stations whose paths are determined to be unreachable is counted, and when the proportion exceeds a preset threshold, the corresponding path is excluded from the positioning calculation, thereby realizing the positioning of the tags in the coal mine underground.

[0112] The method distinguishes between real direct paths and reflected interference paths, reduces the positioning error caused by the complex environment in the coal mine underground, and at the same time, through the statistics of the consensus proportion of the path unreachability of multiple base stations and the setting of a dynamic threshold, avoids the loss of effective paths or the reservation of invalid paths caused by the misjudgment of a single base station, and improves the accuracy and reliability of the positioning result.

[0113] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A UWB-based positioning method in a coal mine, characterized in that, The method comprises: S1: each base station analyzes the tag signal, records the characteristic parameters of the multipath components, the characteristic parameters comprising signal arrival time, signal amplitude and signal phase, generates a characteristic tag containing the characteristic parameters for each path, and establishes a local multipath characteristic database; S2: the first base station receives the tag signal, and when the first base station detects multiple paths of the same tag signal, sends a data request to a nearby second base station, and obtains the characteristic parameters of the multipath components of the same tag signal received by the second base station at the same time; S3: reachability determination of multiple paths of the first base station: cooperative verification of whether there is a shorter time delay path by the second base station, whether the signal amplitude attenuation conforms to the reflection characteristics, whether the signal phase jump matches the dynamic reflection scene, and reachability determination of multiple paths is realized; S4: according to the path reachability determination result fed back by the second base station, the proportion of the base stations judged as unreachable paths is counted, and when the proportion exceeds a preset threshold, the corresponding path is excluded from the positioning calculation; The S3 specifically comprises: The time delay parameters of the multiple paths are called from the local multipath characteristic database of the first base station, the time delay parameter = signal arrival time - signal transmission time, and the theoretical time delay parameter is predicted based on the spatial position of the first base station and the tag signal; If the time delay of the i-th path of the first base station is greater than the theoretical time delay parameter, the time delay parameters of the second base station are traversed, if the time delay of the j-th path of the second base station is less than the time delay of the i-th path of the first base station, the i-th path of the first base station is judged as a suspected reflection path, and if the second base station does not have a path with a time delay less than that of the i-th path of the first base station, the i-th path of the first base station is judged as a path to be further verified; The number of paths of the second base station with a time delay less than that of the path of the first base station is counted, and the proportion of the total number of paths of the second base station is calculated, which is taken as the input value of the time delay dimension; The path to be further verified specifically comprises: The signal amplitude attenuation characteristics of the path to be further verified are called, and the matching degree is calculated with the preset reflection propagation model, the reflection probability score value is generated based on the matching degree difference, and the reflection probability score value is taken as the input value of the signal amplitude dimension; The phase change sequence of the signal cycle of the path to be further verified is called, the non-continuous jump characteristics are identified, the dynamic reflection probability score value is generated according to the amplitude of the jump characteristics, and the reflection probability score value is taken as the input value of the signal phase dimension; The S3 realizes the reachability determination of multiple paths, specifically comprising: A dynamic constraint model related to the time delay parameter, the signal amplitude and the signal phase is established; A joint confidence score is generated according to the weight; When the joint confidence score exceeds a threshold, it is determined that the path is unreachable; The S4 specifically comprises: The first base station collects the independent reachability determination results of each second base station on the same path; The number of second base stations judging the path as unreachable is counted, and the proportion of the total number of second base stations participating in the determination is calculated; When the proportion exceeds a preset threshold, it is confirmed that the path is a real unreachable path, and the path is permanently excluded from the positioning calculation.

2. The UWB-based positioning method for underground coal mine of claim 1, wherein, The S1 includes the following steps: The multipath components of the same tag signal are sorted by the time stamp to establish a time sequence index; A unique path identifier is generated for each path.

3. The UWB-based positioning method for underground coal mine of claim 1, wherein, The S1 includes the following steps: The signal amplitude is converted into a normalized value; The signal phase is subjected to a cyclic redundancy check; A feature vector is generated, which includes the normalized signal amplitude, the signal phase subjected to the cyclic redundancy check, and the signal arrival time.

4. The UWB-based positioning method for underground coal mine of claim 1, wherein, The S2 includes the following steps: A screening radius is set around the first base station, and all base stations within the screening radius are preliminarily screened as candidate base stations; Real-time link evaluation is performed on the candidate base stations, and the evaluation indexes include the signal-to-noise ratio, the bit error rate, the multipath time delay spread, and the clock synchronization deviation of each candidate base station; when the evaluation indexes all meet the preset threshold of the real-time link evaluation, the candidate base stations are screened as the second base stations.

5. The UWB-based positioning method for underground coal mine of claim 4, wherein, The number of the second base stations is dynamically adjusted according to the metal equipment density in the coal mine, and the adjustment includes the following steps: The coal mine is divided into a complex scene with dense equipment and a simple scene with open space according to the number of multipath components; For the complex scene, the number of screened second base stations is increased; For the simple scene, the number of screened second base stations is reduced; If the number of screened second base stations does not meet the preset minimum number requirement, the screening radius is gradually expanded until the number of screened second base stations meets the preset minimum number requirement.

6. A system for implementing the UWB-based underground coal mine positioning method according to claim 1, characterized in that, The system includes the following components: A multipath feature collection and filing system: each base station analyzes the tag signal and records the feature parameters of the multipath components, including the signal arrival time, the signal amplitude, and the signal phase, and generates a feature tag containing the feature parameters for each path, and establishes a local multipath feature database; A cross-base station cooperative data interaction system: the first base station receives the tag signal, and when the first base station detects multiple paths of the same tag signal, sends a data request to the nearby second base station to obtain the feature parameters of the multipath components of the same tag signal received by the second base station at the same time; A multi-dimensional path attribute verification system: the first base station performs reachability determination on multiple paths: through the cooperative verification of the second base station on whether there is a shorter time delay path, whether the signal amplitude attenuation conforms to the reflection characteristics, whether the detection signal phase jump matches the dynamic reflection scene, and the reachability determination of multiple paths is realized; A path validity consensus decision system: according to the path reachability determination results fed back by the second base station, the proportion of base stations determined as unreachable paths is counted, and when the proportion exceeds a preset threshold, the corresponding path is excluded from the positioning calculation.

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