Mine space based on uwb two-way positioning navigation method

Abstract

This application relates to a UWB-based bidirectional positioning and navigation method for underground mines, encompassing the following steps: S1 System deployment and parameter initialization; S2 Establishment of communication link between smart tags and base stations; S3 Execution of DS-TWR bidirectional ranging; S4 Base station-side position calculation and information feedback; S5 Local position calculation of smart tags; S6 Bidirectional verification and real-time updating of positioning results; S7 Navigation information generation and interactive adaptation. This invention, while ensuring no reduction in positioning accuracy, reduces the dependence of positioning results on the backend server, decreases data transmission volume and latency, and improves the system's stability and anti-interference capabilities in complex mine environments. This expands the application scope of UWB positioning technology in mine emergency rescue, autonomous navigation, equipment scheduling, and other scenarios, meeting the diversified needs of mine safety production for positioning technology.

Description

Technical Field

[0001] This invention relates to the field of underground positioning, navigation, and wireless communication technology, and particularly to a UWB-based bidirectional positioning and navigation method for mine spaces. It is applicable to personnel and equipment positioning and navigation scenarios in complex underground mine environments such as coal mines and metal mines. The aim is to optimize the UWB positioning signal interaction and positioning algorithm operation mechanism to achieve simultaneous acquisition of local autonomous positioning results from positioning tags and positioning results from base stations. This provides high-precision positioning technology support for scenarios such as mine safety management, emergency rescue, and equipment scheduling, and represents an extension of industrial wireless positioning and intelligent sensing technology in the mining field. Background Technology

[0002] Underground mines are characterized by dim lighting, confined spaces, and complex geological conditions. Precise positioning of personnel and equipment is a core technological requirement for ensuring safe mine production and improving emergency rescue efficiency. Ultra-wideband (UWB) technology, with its advantages of high temporal resolution, strong resistance to multipath interference, and high positioning accuracy, has become one of the mainstream technologies in mine positioning. Existing UWB-based mine positioning methods generally employ a technical approach combining two-way two-way ranging (DS-TWR) with a trilateration algorithm. The core principle is as follows: multiple positioning anchor points (base stations) with known coordinates are deployed in the mine space. The tag to be positioned performs DS-TWR ranging with at least three anchor points to obtain distance data between the tag and each anchor point. Subsequently, the anchor points upload the calculated distance values ​​to a backend server. Based on the known anchor point coordinates and multiple sets of distance data, the server uses a trilateration algorithm to converge and obtain the precise coordinates of the tag.

[0003] However, the aforementioned existing technologies have significant limitations: the positioning calculation process relies entirely on the backend server, enabling only the base station to know the tag's location, while the tag itself lacks autonomous positioning capabilities and cannot directly obtain its own location information. This deficiency severely limits the application scenarios of the positioning results. For example, in special scenarios such as local communication interruptions in mines, server failures, or emergency rescues, personnel or equipment carried by the tag cannot achieve autonomous navigation, path planning, or emergency avoidance based on their own location information. Furthermore, obtaining positioning results requires multiple data interactions between the server and the tag, increasing data transmission latency and system energy consumption, making it difficult to meet the high requirements for real-time and reliable positioning in the mining industry. Therefore, developing a UWB positioning method that enables bidirectional positioning information acquisition between the base station and the tag has become crucial to overcoming the bottlenecks of existing technologies. Summary of the Invention

[0004] This invention aims to solve the core technical problems of limited application scenarios, insufficient real-time performance, and poor reliability caused by the "one-way positioning" in existing UWB-based mine positioning methods. Specifically, existing technologies, through anchor point and tag ranging and server calculation of tag coordinates, only enable the base station to obtain the tag's location. The tag itself does not have local positioning capabilities and cannot directly output its own location information. This leads to positioning failure in extreme scenarios such as communication interruption and server failure, making it unable to support critical applications such as autonomous navigation and emergency avoidance. At the same time, centralized server calculation requires multiple data interactions, increasing transmission latency and system complexity, making it difficult to adapt to the real-time positioning requirements of complex mine environments.

[0005] To address the aforementioned problems, this invention provides a UWB-based bidirectional positioning and navigation method for mine spaces, comprising the following steps: S1 System Deployment and Parameter Initialization: Deploy UWB positioning base stations in the mine space, plan the base station spacing according to the mine space structure, and ensure that the smart tag at any location in the work area can receive signals from at least 3 base stations. Calibrate the three-dimensional coordinates of each base station and pre-store the coordinate information to the base station's local storage module and the backend server; initialize the configuration of the smart tag and preset the mine space constraint rules. S2 Smart Tag and Base Station Communication Link Establishment: The smart tag scans the surrounding UWB base station signals at a certain frequency and initiates a communication connection request carrying the tag's unique identifier; after receiving the request, the base station completes identity authentication, and after successful authentication, a stable two-way communication link is established; the smart tag performs signal strength detection and screening on the successfully connected base stations; S3 DS-TWR bidirectional ranging execution: The smart tag sequentially performs the DS-TWR bidirectional ranging process with each connected base station in a preset order. Distance measurement is achieved through two signal interactions, eliminating clock synchronization errors of UWB signals during propagation. During the ranging process, the base station and the smart tag calculate and store the distance value based on timestamp data. S4 Base Station Side Position Calculation and Information Feedback: Each base station uploads the measured distance value to the tag, its own precise coordinates, and the distance measurement timestamp to the backend server. The backend server verifies the validity of the uploaded data, and after summarizing at least 3 sets of valid data, it runs the trilateration algorithm to calculate the initial position of the tag. S5 Smart Tag Local Location Calculation: After receiving the base station coordinates and verification results from the backend server, the smart tag first checks the consistency between the locally recorded distance value and the base station distance value fed back by the backend server. If the deviation is ≤0.1m, the data is deemed valid, the built-in positioning calculation module is activated, and the pre-stored trilateration algorithm program is called. If the deviation is >0.1m, the ranging data of this measurement is discarded, and the next ranging cycle is waited for. S6 Positioning Result Two-Way Verification and Real-Time Update: The smart tag feeds back the locally calculated location information to the backend server. The backend server calls the location deviation calculation formula to calculate the error value. If the error is within the preset allowable range, the positioning is confirmed to be valid, and the tag location data on the server is updated to overwrite the historical data. If the error exceeds the allowable range, the positioning result is marked as abnormal, and a re-distance measurement command is triggered. S7 Navigation Information Generation and Interaction Adaptation: The smart tag receives the navigation target set by the user through its built-in input module, combines it with the real-time location calculated locally, and calls the navigation algorithm to generate personalized navigation information; the navigation information is displayed in real time through the tag's built-in LCD display module, and at the same time, it provides feedback to the user in the form of voice broadcast through the voice module.

[0006] To ensure that the tags are adapted to the communication and computing needs of the dim, dusty, and electromagnetically interference-prone environment of the mine, the initial configuration of the smart tags in step S1 includes setting the UWB communication frequency band, signal transmission power, and ranging period. The mine space constraint rules include the roadway boundaries and the coordinate range of prohibited areas.

[0007] To ensure the minimum number of base station connections required for positioning and to lay the foundation for subsequent two-way ranging, the signal strength detection and filtering method in step S2 is as follows: The detection metric is the Received Signal Strength Indicator (RSSI), ensuring that at least three base stations are maintained in a valid connection. If the initial number of connected base stations is less than three, the smart tag expands the scanning range and extends the scanning time until the connection requirements are met.

[0008] In order to calculate accurate distance values ​​and provide core data support for positioning calculations, the DS-TWR two-way ranging process in step S3 is as follows: ① The smart tag sends a ranging start signal to the base station at time T1; ② The base station receives the start signal at time T2, and after a 5ns delay, sends a response signal back to the tag at time T3; ③ The smart tag receives a response signal at time T4 and records the timestamps T1 and T4; ④ The base station sends a ranging confirmation signal to the tag at time T5. After receiving the confirmation signal at time T6, the tag sends back the final response. The base station synchronously records the timestamps T2, T3, and T5. ⑤ The base station uses its own recorded T2, T3, T5 and the T1, T4, T6 fed back by the smart tag to calculate the distance between the tag and the base station using the DS-TWR distance formula; the smart tag uses the same formula to calculate the distance value based on its locally recorded T1, T4, T6 and the T2, T3, T5 fed back by the base station, thus completing the bidirectional acquisition and recording of distance information.

[0009] To enable the base station to perceive the location of the smart tag and to provide benchmark data and verification basis for the local positioning of the smart tag, the weighted iterative trilateration algorithm in step S4 is as follows: ① Weighted equation for distance measurement: in,( , , ( ) is the precise 3D positioning coordinate of the smart tag, ( , , Let be the calibrated three-dimensional coordinates of the i-th UWB base station. The weighted ranging value between the smart tag and the i-th base station is... Let be the signal weighting coefficient of the i-th base station. Let be the positioning accuracy correction term for the i-th base station. The number of base stations participating in the positioning; ② Iterative formula for weighting coefficients: in, t For the number of iterations, The step size coefficient for weight iteration. Let be the ranging value between the smart tag and the i-th base station at the t-th iteration; ③ Least squares objective function: in, Let be the error weighting coefficient for the i-th base station; ④ Iteration termination condition: in, The least squares objective function value. The coordinates of the label are obtained in the t-th iteration. The convergence threshold of the objective function; During the solution process, the initial values ​​of the weighting coefficients for each base station are first determined based on the base station signal strength and communication delay. Combined with distance measurement values The initial weighted ranging values ​​are obtained; a least-squares objective function is constructed, and the nonlinear equations are linearized through Taylor series expansion to obtain the tag coordinates for the first iteration. Update the weight coefficients according to the iterative formula. Substitute the values ​​into the objective function to calculate the new function value. Repeat the above iterative process until the difference between the objective function values ​​of two adjacent iterations is less than the convergence threshold. Stop the iteration and output the final positioning coordinates.

[0010] To enable smart tags to perceive their own location in real time and expand the application scenarios of positioning technology, in step S5, during the local location calculation process of the smart tag, a trilateration algorithm is run to obtain the base station coordinates. （ 1 , 1 , 1 ； 2 , 2 , 2 ； 3 , 3 , 3 ） Local effective distance value （ 1 '、 2 '、 3 '） Substituting the equations from the trilateration algorithm in step S4, the local initial position is obtained. （ ', ', '） Subsequently, the calculation results were corrected based on the pre-set mine space constraint rules during initialization. （ ', ', '） If the position exceeds the constraint range, the coordinates are adjusted based on the nearest roadway boundary to ultimately calculate the precise three-dimensional position. The positioning accuracy is controlled within ±0.3m.

[0011] To ensure the real-time accuracy of the smart tag's location information while it is in motion, and to provide reliable data for the dynamic monitoring of mine workers / equipment, in step S6, after the re-ranging command is triggered, the smart tag and the base station execute the DS-TWR two-way ranging process in step S3 again, repeating steps S3-S5 until the positioning result error is ≤0.3m; the smart tag and the backend server repeat the above positioning process according to a preset cycle.

[0012] To support overall mine monitoring and emergency dispatch, and to fully leverage the application value of two-way positioning technology, in step S7, the navigation information includes the straight-line distance between the current location and the target location, the direction of travel, the remaining distance to the target, and obstacle avoidance reminders within the roadway.

[0013] In summary, compared with the prior art, the present invention has the following technical advantages and beneficial effects: (1) This invention optimizes the UWB positioning signal interaction process by adding a signal transmission link to build a two-way ranging data transmission channel between the base station and the tag, ensuring that the distance data between the anchor point and the tag can be obtained by the base station and the tag simultaneously. (2) This invention endows the tag with local computing capabilities. By building a computing module in the smart tag, it can run a trilateration algorithm locally to autonomously complete its own position calculation based on the obtained anchor point coordinates and distance data, so as to realize the synchronous knowledge of the positioning results between the tag and the base station. (3) Under the premise of ensuring that the positioning accuracy is not reduced, the present invention reduces the dependence of the positioning results on the back-end server, reduces the amount of data transmission and delay, improves the stability and anti-interference ability of the system in the complex environment of the mine, and expands the application scope of UWB positioning technology in mine emergency rescue, autonomous navigation, equipment scheduling and other scenarios, so as to meet the diversified needs of mine safety production for positioning technology. Attached Figure Description

[0014] Figure 1 This is a flowchart of the UWB-based bidirectional positioning and navigation method for mine space according to the present invention; Figure 2 This is a comparison chart of the positioning errors of the present invention and existing technologies under different mining environments; Figure 3 This is a comparison chart of the positioning effectiveness of the present invention and existing technologies as a function of the base station outage rate; Figure 4 This is a comparison chart of the travel deviation between the present invention and existing technologies in different navigation scenarios; Figure 5 This is a comparison chart of the dynamic response lag time of the present invention and the prior art as a function of moving speed. Detailed Implementation

[0015] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0016] like Figure 1 The method for two-way positioning and navigation in mine space based on UWB, as shown, includes the following steps: S1 System deployment and parameter initialization; S2 Establishment of communication link between smart tag and base station; S3 Execution of DS-TWR bidirectional ranging; S4 Base station side location calculation and information feedback; S5 Local location calculation of smart tag; S6 Bidirectional verification and real-time update of positioning results; S7 Navigation information generation and interactive adaptation.

[0017] The steps of this invention will be described in detail below.

[0018] S1 System Deployment and Parameter Initialization: The core objective of this step is to complete the hardware deployment and basic parameter configuration of the positioning system, providing accurate reference data for subsequent two-way ranging and positioning calculations. Among these, the accuracy of base station coordinate calibration directly determines the final positioning error and must be strictly controlled.

[0019] UWB positioning base stations (anchor points) are deployed in the mine space (key areas such as roadways and working faces). The spacing between base stations is planned according to the mine space structure (e.g., roadway width 4-6m, length 50-100m / segment, curvature radius ≥8m at turns) to ensure that smart tags at any location in the working area can receive signals from at least 3 base stations, and the three-dimensional coordinates of each base station are calibrated. , , The coordinate unit is meters (m), and the coordinate information is pre-stored in the local storage module of the base station and the backend server; the smart tag is initialized and configured, and the mine space constraint rules are preset; The initial configuration of smart tags includes setting parameters such as UWB communication frequency band, signal transmission power, and ranging period; and preset mine space constraint rules (such as roadway boundaries). ∈[0,2000]m、 ∈[0,400]m、 ∈[0,8]m, entry into the region coordinate range is prohibited. ∈[18,22]m、 ∈[18,22]m), ensuring that the label is adapted to the communication and computing needs of the dim, dusty, and electromagnetically interfered environment of the mine.

[0020] S2 smart tag establishes communication link with base station: The stability and signal quality of the communication link are prerequisites for ensuring ranging accuracy. This step eliminates interfering links through identity authentication and signal filtering to ensure the minimum number of base station connections required for positioning, laying the foundation for subsequent two-way ranging.

[0021] After the smart tag is activated, it scans the surrounding UWB base station signals at a frequency of 500ms / time and initiates a communication connection request carrying the tag's unique identifier (ID: 001-999). After receiving the request, the base station completes identity authentication. After successful authentication, a stable two-way communication link is established, and the link communication delay is controlled within ≤10ns. The smart tag performs signal strength detection (using Received Signal Strength Indicator (RSSI) in dBm) and filtering on successfully connected base stations, retaining links with RSSI ≥ -70dBm and communication latency fluctuation ≤ 2ns. This ensures that at least three base stations are maintained as valid connections, meeting the basic requirement of "three non-collinear anchor points" for trilateration. If the initial number of connected base stations is less than three, the tag expands its scanning range (from 120° to 180°) and extends the scanning time to 1 second until the connection requirements are met.

[0022] S3 DS-TWR bidirectional ranging execution: DS-TWR (Two-way Two-sided Ranging) technology achieves distance measurement through two signal interactions, which can effectively eliminate clock synchronization errors in the propagation process of UWB signals. This step obtains timestamp data through two-way signal interaction between the tag and the base station, and then calculates accurate distance values, providing core data support for positioning calculations.

[0023] The smart tag sequentially performs the DS-TWR bidirectional ranging process with each connected base station in a preset order (ascending order by base station ID). Distance measurement is achieved through two signal interactions, eliminating clock synchronization errors in the UWB signal propagation process. ① The smart tag sends a ranging start signal (the signal type is UWB pulse signal) to the base station at time T1. ② The base station receives the start signal at time T2, and after a 5ns delay, sends a response signal back to the tag at time T3; ③ The smart tag receives a response signal at time T4 and records the timestamps T1 and T4; ④ The base station sends a ranging confirmation signal to the tag at time T5. After receiving the confirmation signal at time T6, the tag sends back the final response. The base station synchronously records the timestamps T2, T3, and T5. The timestamp unit is nanoseconds (ns), which is provided by the high-precision crystal oscillator clock of the tag and the base station. ⑤ During the ranging process, the base station and the smart tag calculate and store the distance value based on the timestamp data: The base station uses its own recorded T2, T3, T5 and the T1, T4, T6 fed back by the smart tag to calculate the distance between the tag and the base station using the DS-TWR distance formula; The smart tag uses its locally recorded T1, T4, T6 and the T2, T3, T5 fed back by the base station to calculate the distance value autonomously using the same formula, thus completing the bidirectional acquisition and recording of distance information.

[0024] The DS-TWR two-way ranging optimization method is as follows: In the formula: The precise straight-line distance between the smart tag and the corresponding base station, in meters (m). The propagation speed of a UWB signal in a standard vacuum environment is 2.99792458 × 10⁻⁶. 8 m / s; The time when the smart tag sends the ranging start signal, in nanoseconds (ns). The time when the base station receives the ranging start signal, in nanoseconds (ns). The time it takes for a base station to send a response signal is measured in nanoseconds (ns). The time it takes for a smart tag to receive a response signal, measured in nanoseconds (ns). : UWB signal penetration loss correction factor, unitless, calculated based on the type and thickness of the roadway support material. Where μ is the attenuation coefficient of the support material (μ=0.05m for concrete). -1 Metal support μ=0.12m -1 Anchor spray support μ=0.03m -1 h is the thickness of the support material (unit: m); Signal attenuation coupling coefficient, dimensionless, ranging from 0.01 to 0.05, determined by the uniformity of the mine air medium; Distance attenuation coefficient, in meters. -1 The value ranges from 0.002 to 0.01. The initial estimated distance between the smart tag and the base station, in meters (m), is calculated from the initial RSSI signal strength using the following formula: ,in Tag transmit power (unit: dBm). The path loss (in dB) is at a reference distance (1m), and n is the path loss exponent. Temperature, humidity and air pressure coupling compensation term, unit is meters (m). Where t is the real-time temperature of the mine (unit: °C), RH is the real-time relative humidity (unit: %), P is the real-time air pressure (unit: kPa), a=0.002 m / ℃, b=0.001 m / %, c=0.0005 m / kPa; Dust scattering compensation term, unit is meter (m), calculation method is as follows: , where ρ is the mine dust concentration (unit: mg / m³), σ is the dust scattering coefficient (unit: m³ / mg), and τ is the signal propagation time correction factor (unitless). The multipath reflection interference compensation term for the tunnel wall, in meters (m), is calculated as follows: Where w is the tunnel width (m), θ is the signal incident angle (rad), and γ is the tunnel wall reflection attenuation coefficient (m). -1 ); Clock synchronization error compensation term, in meters (m), is determined by the frequency deviation between the tag and the base station crystal oscillator. , where Δf is the crystal oscillator frequency deviation (unit: Hz). The signal propagation time (in seconds).

[0025] S4 Base Station Side Location Calculation and Information Feedback: This step aggregates ranging data and coordinate information from multiple base stations through a backend server, calculates the initial position of the tag using a trilateration algorithm, and feeds back the core data to the smart tag. This not only enables the base station to perceive the position of the smart tag, but also provides benchmark data and verification basis for the local positioning of the smart tag.

[0026] Each base station will measure the distance value to the tag (e.g. , , ), its own precise coordinates (such as A 1 （ 1 , 1 , 1 ）、A 2 （ 2 , 2 , 2 ）、A 3 （ 3 , 3 , 3 ） The data, along with the ranging timestamp, is uploaded to the backend server at the same interval as the ranging interval (1 second / time). The backend server verifies the validity of the uploaded data (removing data whose distance values ​​exceed the base station's communication range (0-50m)). After aggregating at least three sets of valid data, the trilateration algorithm is run to calculate the tag's initial position. （ 0 , 0 , 0 ） ; The server will calculate the initial position of the label. （ 0 , 0 , 0 ） Precise coordinates of each base station involved in the positioning （ 1 , 1 , 1 ； 2 , 2 , 2 ； 3 , 3 , 3 ） The verification results of ranging data (such as data validity indicators: 1 for valid, 0 for invalid) are fed back to the smart tag through the UWB communication link, with the feedback delay controlled within ≤50ns, providing basic data support for the tag's local positioning.

[0027] The weighted iterative trilateration algorithm is as follows (based on a three-dimensional rectangular coordinate system and least squares iterative optimization): ① Weighted equation for distance measurement: in,( , , ) represents the precise three-dimensional positioning coordinates of the smart tag, in meters (m); ( , , ) represents the calibrated three-dimensional coordinates of the i-th UWB base station (anchor point), in meters (m); The weighted ranging value between the smart tag and the i-th base station is expressed in meters (m). Let be the signal weight coefficient of the i-th base station, which is dimensionless and whose initial value is determined jointly by communication quality and signal strength, as shown in the formula: ,in Let be the received signal strength of the i-th base station (in dBm). β is the communication delay fluctuation value (unit: ns), and β is the delay attenuation coefficient (unit: ns⁻¹). This is the positioning accuracy correction term for the i-th base station, expressed in square meters (m²), and is coupled with the positioning priority and environmental complexity of the mine area. ,in Based on the correction threshold (mining face) =0.001 m², transport roadway =0.003 m²), where γ is the environmental complexity coefficient. Let be the environmental complexity index of the coverage area of ​​the i-th base station; The number of base stations participating in the positioning process, without units. ≥3; ② Iterative formula for weighting coefficients: in, t The number of iterations, unitless, initial value. t =0; This is the step size coefficient for the weight iteration; it is dimensionless and ranges from 0.05 to 0.2. Let be the distance between the smart tag and the i-th base station at the t-th iteration, in meters (m). ③ Least squares objective function: in, Let be the error weighting coefficient of the i-th base station, which is dimensionless and related to . negative correlation ,in Let be the standard deviation of the ranging error of the i-th base station (unit: m); ④ Iteration termination condition: in, The value is the least squares objective function value, which is unitless. The coordinates of the label obtained in the t-th iteration are in meters (m). This is the convergence threshold for the objective function, dimensionless, and its value ranges from 10. -6 ~10 -4 .

[0028] During the solution process, the initial values ​​of the weighting coefficients for each base station are first determined based on the base station signal strength and communication delay. Combined with distance measurement values The initial weighted ranging values ​​are obtained; a least-squares objective function is constructed, and the nonlinear equations are linearized through Taylor series expansion to obtain the tag coordinates for the first iteration. Update the weight coefficients according to the iterative formula. Substitute the values ​​into the objective function to calculate the new function value. Repeat the above iterative process until the difference between the objective function values ​​of two adjacent iterations is less than the convergence threshold. The iteration is stopped and the final location coordinates are output. Throughout the iteration process, mine space constraints (such as roadway boundaries and the coordinate range of prohibited areas) are introduced to prune the intermediate results of the iteration, so as to avoid physical infeasible location solutions.

[0029] S5 Smart Tag Local Location Calculation: This step is the core of achieving two-way positioning. Through the built-in computing module of the smart tag, it uses the reference data fed back by the server and the ranging data stored locally to autonomously run the trilateration algorithm and correct the results by combining spatial constraint rules, so that the tag can perceive its own position in real time and expand the application scenarios of positioning technology.

[0030] After receiving the base station coordinates and verification results from the backend server, the smart tag first checks the distance value recorded locally. （ 1 '、 2 '、 3 '） Distance value between the base station and the backend server（ 1 、 2 、 3 ） A consistency check is performed. If the deviation is ≤0.1m, the data is deemed valid. The built-in positioning calculation module is activated, and the pre-stored trilateration algorithm program is called. If the deviation is >0.1m, the ranging data of this measurement is discarded, and the next ranging cycle is waited for. The smart tag runs a trilateration algorithm locally to determine the base station coordinates. （ 1 , 1 , 1 ； 2 , 2 , 2 ； 3 , 3 , 3 ） Local effective distance value （ 1 '、 2 '、 3 '） Substituting the equations from the trilateration algorithm in step S4, the local initial position is obtained. （ ', ', '） Then, the pre-set mine space constraint rules (such as roadway boundaries) are combined with the initialization. ∈[5,45]m、 The calculation results are corrected if ∈[3,30]m). （ ', ', '） If the coordinates exceed the constraint range, they will be adjusted based on the nearest roadway boundary (e.g., ' When =46m, correct to ' =45m), finally calculating its precise three-dimensional position. The positioning accuracy is controlled within ±0.3m.

[0031] S6 positioning results bidirectional verification and real-time update: By verifying the positioning results from both the base station side and the smart tag side, positioning accuracy can be further improved and abnormal data can be eliminated. At the same time, through periodic updates, the location information of the tags in motion can be ensured to be accurate in real time, providing reliable data for the dynamic monitoring of mine workers / equipment.

[0032] Smart tags will calculate the location information locally. Feedback is sent to the backend server, which uses the position deviation calculation formula to calculate the error value. If the error is within the preset allowable range (the positioning accuracy requirement in the mine is ±0.3m, i.e., error ≤0.3m), the positioning is confirmed to be valid, and the tag position data on the server is updated to overwrite the historical data. If the error exceeds the allowable range, the positioning result is marked as abnormal, triggering a re-distance measurement command. After the re-ranging command is triggered, the smart tag and the base station execute the DS-TWR two-way ranging process in step S3 again, repeating steps S3-S5 until the positioning result error is ≤0.3m. The smart tag and the server repeat the above positioning process at a preset cycle (1s / time). For tags in a moving state (moving speed ≤1.5m / s), the ranging cycle can be dynamically adjusted to 0.5s / time to ensure the real-time location update during movement and achieve continuous and accurate positioning in a moving state.

[0033] The optimization method for bidirectional verification of positioning results is as follows: In the formula: : The precise deviation between the local positioning result and the server positioning result, in meters (m). : The three-dimensional coordinates of the smart tag calculated locally, in meters (m); （ 0 , 0 , 0 ）The initial three-dimensional coordinates of the tag are obtained by the backend server through an iterative trilateration algorithm, in meters (m). α , β , γ : Three-dimensional coordinate axis weighting coefficient, unitless, dynamically adjusted based on mine spatial characteristics and positioning accuracy requirements; 、 、 : Three-dimensional coordinate deviation attenuation coefficient, unit is m -1 The value ranges from 0.1 to 0.5; : Dynamic error coupling correction coefficient, dimensionless, and related to the depth of tag movement state; v Tag movement speed, in meters per second (m / s); τ : Tag continuous positioning time, in seconds (s).

[0034] S7 Navigation Information Generation and Interaction Adaptation: Navigation information is generated based on the accurate local location information of smart tags, realizing the integration of positioning and navigation; at the same time, through real-time data interaction between tags and servers, it supports the overall monitoring and emergency dispatch of the mine, giving full play to the application value of two-way positioning technology.

[0035] The smart tag receives user-defined navigation targets (such as work point B (35.60, 6.10, 2.30)m, emergency escape route entrance C (40.20, 25.30, 2.30)m, and mine exit D (5.50, 15.20, 2.30)m) through its built-in input module, and combines this with the real-time location calculated locally. The system uses navigation algorithms to generate personalized navigation information, which includes: the straight-line distance between the current location and the target location (calculated using the distance formula between two points), the direction of travel (calculated based on the azimuth formula), the remaining distance to the target, and obstacle avoidance reminders in alleyways (obstacle coordinates are pre-stored locally on the tag). The navigation information is displayed in real time through the tag's built-in LCD display module, and is also fed back to the user via voice broadcast through the voice module at a frequency of 10 seconds per broadcast.

[0036] The smart tags upload their real-time location and navigation status (such as whether they have deviated from the route; the deviation criterion is a distance > 0.5m from the planned route) to the server every second. The backend system, based on a GIS mine map, visualizes all tag location information. Managers can use the backend system to achieve global monitoring and dispatch of mine workers or equipment (such as dispatching workers to designated work points). In case of emergencies (such as tunnel collapse, the coordinates of the collapsed area...), the system can also be used to monitor and dispatch mine workers or equipment globally (such as dispatching workers to designated work points). ∈[25,30]m、 When the value is in the range of [8,12]m, the system can quickly trace the location of all tags, send evacuation instructions to the tags in the danger zone, guide them to evacuate through the nearest safe passage, and improve the efficiency of emergency rescue.

[0037] The optimization method for navigation information generation is as follows: ① Actual path distance calculation (including multipath and turning loss correction): in, L : The actual path distance between the current location and the navigation target, in meters (m); : The three-dimensional coordinates of the navigation target, in meters (m); The real-time 3D position of the smart tag is in meters (m). : Number of turns in the roadway between the current location and the target location, without unit; : The turning angle at the i-th turn, in radians (rad); : Dust average concentration influence coefficient, unit is m³ / mg; : Average dust concentration between the current location and the target location, in mg / m³.

[0038] ② Precise azimuth calculation (including magnetic declination, metal interference, and terrain correction): : The precise azimuth angle between the direction of travel and true north, in degrees (°), with a range of 0° to 360°; (·): The arctangent function for the four quadrants, with the output value in radians (rad). Magnetic declination in the mining area, in radians (rad), is obtained from local magnetic survey data corrected for altitude. The calculation method is as follows: ,in denoted as the reference magnetic declination (in rad), and h as the mine elevation (in km). Altitude correction factor (unit: rad / km); Radius to angle coefficient, unitless; : Inclination angle of tunnel section, in radians (rad).

[0039] The following is combined Figure 2-5 The present invention is compared and explained with related methods in the prior art.

[0040] like Figure 2 As shown, the positioning errors of the present invention and the prior art are compared under different mining environments (normal environment: t=25℃, RH=60%, ρ=1mg / m³; high temperature and high humidity environment: t=35℃, RH=85%, ρ=1mg / m³; high dust environment: t=25℃, RH=60%, ρ=5mg / m³; strong electromagnetic interference environment: t=25℃, RH=60%, E=10V / m; complex mixed environment: t=35℃, RH=85%, ρ=5mg / m³, E=10V / m). The horizontal axis represents the mining environment type, and the vertical axis represents the positioning error (unit: m). The two broken lines represent the prior art (black, circle) and the present invention (gray, square), respectively. The comparison shows that the positioning error of the present invention is significantly lower than that of the prior art in all environments, especially in complex mixed environments, demonstrating the effectiveness of the multi-field coupling error compensation mechanism.

[0041] like Figure 3 As shown, the horizontal axis represents the base station outage rate (0%~30%, step size 5%), and the vertical axis represents the positioning efficiency (%). The two curves represent the present invention and the prior art, respectively. Because the prior art relies on calculations from a single base station, its efficiency drops rapidly as the base station outage rate increases. The present invention, through bidirectional positioning calculations and a dynamic link replenishment mechanism, maintains an efficiency of over 98% when the base station outage rate is ≤15%, and even when the outage rate reaches 30%, the efficiency still reaches 85%, significantly higher than the prior art (52%).

[0042] like Figure 4 As shown, the horizontal axis represents the navigation scenario (straight lane, single-turn lane, multi-turn lane, and slope lane), and the vertical axis represents the travel deviation (unit: m), representing the prior art and the present invention, respectively. The prior art does not consider factors such as turning losses and terrain slope, resulting in a travel deviation of 1.2~1.5m in multi-turn and slope lanes; the present invention incorporates the effects of turning losses and dust through the actual path distance formula, and supplements the magnetic declination and slope correction through the azimuth formula, achieving a travel deviation of ≤0.3m in all scenarios.

[0043] like Figure 5 The figure shows the dynamic response lag time as a function of moving speed, where the scatter points represent measured data and the fitted line represents the trend change. Existing technologies use a fixed 1-second ranging period, and the lag time increases linearly with speed (1.5 seconds lag at 2 m / s). This invention employs a dynamic ranging period adjustment mechanism, ensuring a lag time of ≤0.1 seconds at speeds ≤0.5 m / s, and still ≤0.2 seconds at speeds ≤2 m / s. The slope of the fitted line is significantly lower than that of existing technologies.

[0044] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape, principle and application direction of this application should be covered within the scope of protection of this application.

Claims

1. A UWB-based bidirectional positioning and navigation method for mine space, characterized in that, Includes the following steps: S1 System Deployment and Parameter Initialization: Deploy UWB positioning base stations in the mine space, plan the base station spacing according to the mine space structure, ensure that the smart tag at any location in the work area can receive signals from at least 3 base stations, calibrate the three-dimensional coordinates of each base station, and pre-store the coordinate information to the base station's local storage module and the backend server. Initialize and configure the smart tags, and preset the mine space constraint rules; S2 Smart Tag and Base Station Communication Link Establishment: The smart tag scans the surrounding UWB base station signals at a certain frequency and initiates a communication connection request carrying the tag's unique identifier; after receiving the request, the base station completes identity authentication, and after successful authentication, a stable two-way communication link is established; the smart tag performs signal strength detection and screening on the successfully connected base stations; S3 DS-TWR bidirectional ranging execution: The smart tag sequentially performs the DS-TWR bidirectional ranging process with each connected base station in a preset order, realizing distance measurement through two signal interactions and eliminating clock synchronization errors of UWB signals during propagation; During the ranging process, the base station and the smart tag calculate and store the distance value based on the timestamp data, respectively; S4 Base Station Side Position Calculation and Information Feedback: Each base station uploads the measured distance value to the tag, its own precise coordinates, and the distance measurement timestamp to the backend server. The backend server verifies the validity of the uploaded data, and after summarizing at least 3 sets of valid data, it runs the trilateration algorithm to calculate the initial position of the tag. S5 Smart Tag Local Location Calculation: After receiving the base station coordinates and verification results from the backend server, the smart tag first checks the consistency between the locally recorded distance value and the base station distance value fed back by the backend server. If the deviation is ≤0.1m, the data is deemed valid, the built-in positioning calculation module is activated, and the pre-stored trilateration algorithm program is called. If the deviation is >0.1m, the ranging data of this measurement is discarded, and the next ranging cycle is waited for. S6 Positioning Result Two-Way Verification and Real-Time Update: The smart tag feeds back the locally calculated location information to the backend server. The backend server calls the location deviation calculation formula to calculate the error value. If the error is within the preset allowable range, the positioning is confirmed to be valid, and the tag location data on the server is updated to overwrite the historical data. If the error exceeds the allowable range, the positioning result is marked as abnormal, and a re-distance measurement command is triggered. S7 Navigation Information Generation and Interaction Adaptation: The smart tag receives the navigation target set by the user through its built-in input module, combines it with the real-time location calculated locally, and calls the navigation algorithm to generate personalized navigation information; Navigation information is displayed in real time via the LCD display module built into the label, and is also provided to the user via voice broadcast through the voice module.

2. The UWB-based bidirectional positioning and navigation method for mine space according to claim 1, characterized in that, In step S1, the initial configuration of the smart tag includes setting the UWB communication frequency band, signal transmission power and ranging period, and the mine space constraint rules include the roadway boundary and the coordinate range of the prohibited area.

3. The UWB-based bidirectional positioning and navigation method for mine space according to claim 2, characterized in that, In step S2, the method for signal strength detection and filtering is as follows: The detection metric is the Received Signal Strength Indicator (RSSI), ensuring that at least three base stations are maintained in a valid connection. If the initial number of connected base stations is less than three, the smart tag expands the scanning range and extends the scanning time until the connection requirements are met.

4. The UWB-based bidirectional positioning and navigation method for mine space according to claim 3, characterized in that, In step S3, the DS-TWR two-way ranging procedure is as follows: ① The smart tag sends a ranging start signal to the base station at time T1; ② The base station receives the start signal at time T2, and after a 5ns delay, sends a response signal back to the tag at time T3; ③ The smart tag receives a response signal at time T4 and records the timestamps T1 and T4; ④ The base station sends a ranging confirmation signal to the tag at time T5. After receiving the confirmation signal at time T6, the tag sends back the final response. The base station synchronously records the timestamps T2, T3, and T5. ⑤ The base station uses its own recorded T2, T3, T5 and the T1, T4, T6 fed back by the smart tag to calculate the distance between the tag and the base station using the DS-TWR distance formula; the smart tag uses the same formula to calculate the distance value based on its locally recorded T1, T4, T6 and the T2, T3, T5 fed back by the base station, thus completing the bidirectional acquisition and recording of distance information.

5. The UWB-based bidirectional positioning and navigation method for mine space according to claim 4, characterized in that, In step S4, the weighted iterative trilateration algorithm is as follows: ① Weighted equation for distance measurement: in,( , , ( ) is the precise 3D positioning coordinate of the smart tag, ( , , Let be the calibrated three-dimensional coordinates of the i-th UWB base station. The weighted ranging value between the smart tag and the i-th base station. Let be the signal weighting coefficient of the i-th base station. Let be the positioning accuracy correction term for the i-th base station. The number of base stations participating in the positioning; ② Iterative formula for weighting coefficients: in, t For the number of iterations, The step size coefficient for weight iteration. Let be the ranging value between the smart tag and the i-th base station at the t-th iteration; ③ Least squares objective function: in, Let be the error weighting coefficient for the i-th base station; ④ Iteration termination condition: in, The value of the least squares objective function. The coordinates of the label are obtained in the t-th iteration. The convergence threshold of the objective function; During the solution process, the initial values ​​of the weighting coefficients for each base station are first determined based on the base station signal strength and communication delay. Combined with distance measurement values The initial weighted ranging values ​​are obtained; a least-squares objective function is constructed, and the nonlinear equations are linearized through Taylor series expansion to obtain the tag coordinates for the first iteration. Update the weight coefficients according to the iterative formula. Substitute the values ​​into the objective function to calculate the new function value. Repeat the above iterative process until the difference between the objective function values ​​of two adjacent iterations is less than the convergence threshold. Stop the iteration and output the final positioning coordinates.

6. The UWB-based bidirectional positioning and navigation method for mine space according to claim 5, characterized in that, In step S5, during the local location calculation of the smart tag, a trilateration algorithm is run to determine the base station coordinates. （ 1 , 1 , 1 ； 2 , 2 , 2 ； 3 , 3 , 3 ） Local effective distance value （ 1 '、 2 '、 3 '） Substituting the equations from the trilateration algorithm in step S4, the local initial position is obtained. （ ', ', '） Subsequently, the calculation results were corrected based on the pre-set mine space constraint rules during initialization. （ ', ', '） If the position exceeds the constraint range, the coordinates are adjusted based on the nearest roadway boundary to ultimately calculate the precise three-dimensional position. The positioning accuracy is controlled within ±0.3m.

7. The UWB-based bidirectional positioning and navigation method for mine space according to claim 6, characterized in that, In step S6, after the re-ranging command is triggered, the smart tag and the base station execute the DS-TWR two-way ranging process in step S3 again, repeating steps S3-S5 until the positioning result error is ≤0.3m; the smart tag and the back-end server repeat the above positioning process according to a preset cycle.

8. The UWB-based bidirectional positioning and navigation method for mine space according to claim 7, characterized in that, In step S7, the navigation information includes the straight-line distance between the current location and the target location, the direction of travel, the remaining distance to the target, and obstacle avoidance reminders in the alleyway.

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