A Three-Dimensional Network Optimization Method for UWB Base Stations Based on a Closed Space Model

Abstract

This invention discloses a method for optimizing the 3D network topology of UWB base stations based on a closed space model, comprising the following steps: UWB base station attribute input: responsible for acquiring UWB base station equipment information, including the base station antenna height, effective coverage distance of the base station signal, and important parameters of angle measurement error; Digital model input and recognition of the positioning scene: by reading the 3D digital model of the closed space (OBJ format), automatically reading relevant information from the model and extracting the positioning area boundary, base station deployment range, and terrain data; identifying the scene type, determining the positioning method, and constructing the optimal mathematical model for the deployment of multiple UWB base stations and multiple single UWB base stations. This invention, by reading indoor 3D model information, selects multiple UWB base stations for deployment in open environments and single UWB base stations for deployment in narrow environments, optimizing the UWB base station network topology within the limited detection distance range of the base stations, effectively optimizing the network structure and improving UWB positioning accuracy.

Description

Technical Field

[0001] This invention relates to the field of wireless positioning and navigation in enclosed spaces, and in particular to a method for optimizing the three-dimensional network topology of UWB base stations based on an enclosed space model. Background Technology

[0002] Currently, navigation and positioning in enclosed spaces such as indoors or underground has become a research hotspot. Ultra-wideband (UWB) has become the primary positioning method due to its advantages such as insensitivity to channel fading, low interception capability, and high positioning accuracy. UWB positioning algorithms are gradually maturing. However, due to the limited operating range of UWB base stations and the complex structure of enclosed spaces, it is necessary to optimize the network layout of UWB base stations to ensure positioning efficiency and save costs. Some scholars have designed corresponding network optimization rules for regular indoor scenarios, but these are based on multiple ranging UWB base stations and two-dimensional plane base station network optimization in open areas. The positioning area and base station deployment are placed on the same plane, which is a two-dimensional network layout and does not consider the three-dimensional positioning effect of complex three-dimensional structures in enclosed spaces. Furthermore, research on deployment optimization for novel UWB single-base station positioning modes based on ranging and angle measurement, as well as for narrow and elongated scenarios, has not yet been conducted. Existing methods are based on digital models of enclosed spaces for three-dimensional network optimization, overcoming the problem of ill-conditioned multi-UWB base station networks and solving the problem of single-UWB base station deployment in narrow spaces. This approach moves from empirical network deployment to precise network deployment, improving positioning accuracy and saving manpower and financial costs. Summary of the Invention

[0003] The purpose of this invention is to provide a three-dimensional network optimization method for UWB base stations based on a closed space model, thereby solving the aforementioned problems existing in the prior art.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for optimizing the three-dimensional network topology of UWB base stations based on a closed space model includes the following steps:

[0006] S1, UWB base station attribute input: Responsible for obtaining UWB base station equipment information, including the base station antenna height, the effective coverage distance of the base station signal, and important parameters of angle measurement error, so as to realize the instantiation of ranging UWB base station and ranging and angle measuring UWB base station;

[0007] S2. Location Scene Digital Model Input and Recognition: By reading the 3D digital model of the enclosed space in OBJ format, the system automatically reads relevant information from the model and extracts the location area boundary, base station deployment range, and terrain data; Model Component Recognition: The system reads and recognizes the entity information of the interior walls, ceiling, floor, and columns of the read indoor 3D model.

[0008] S3. Identify the scene type and determine the positioning method. If the actual scene is an open environment, the ranging UWB multi-base station positioning mode is adopted, which has high accuracy. If the actual scene is a narrow scene, the ranging and angle measuring UWB single-base station positioning mode is adopted.

[0009] S4. Construct an optimal mathematical model for the deployment of multiple UWB base stations;

[0010] S5. Construct an optimal mathematical model for the deployment of multiple UWB single base stations.

[0011] Furthermore, the specific method of step S4 includes:

[0012] After obtaining the reference coordinates of the location service area through the digital model, the reference coordinates of the service area are transformed into a local coordinate system;

[0013] The transformation formula between the local coordinate system and the reference coordinate system is as follows:

[0014]

[0015] In the above formula, (X l ,Y l (X) represents the local coordinates of a ground grid point. g ,Y g (X) represents the reference coordinates of the ground grid points. o ,Y o () represents the reference coordinates of the origin of the local coordinate system. This is the rotation angle between the local coordinate system and the reference coordinate system.

[0016] Furthermore, the specific method of step S4 includes:

[0017] The location service area is divided into N equal-sized two-dimensional grids W by selecting gridded sampling points. i =xy, i=1,2…N, the label position is located on a two-dimensional grid point; the grid size of the positioning area is defined according to different requirements.

[0018] Furthermore, the specific method of step S4 also includes:

[0019] The deployment area for UWB base stations is selected and divided into a three-dimensional grid of equal size. i =xyz, i=1,2…N, the UWB base station is located on the three-dimensional grid points; the grid size of the base station deployment area is defined according to different requirements.

[0020] Furthermore, the specific method of step S4 also includes:

[0021] The evaluation index is the DOP (Depth of Precision) of the spatial location. Multi-station UWB deployments under different network configurations have different positioning accuracies for the same three-dimensional spatial positioning target.

[0022] The optimal mesh layout is obtained by comparing the minimum DOP under different mesh shapes. The definition of DOP is:

[0023] DOP = σ p / σ m

[0024] In the above formula, σ p For the user's location error, σ m For measurement error;

[0025] The relationships between the Position Dilution of Precision (PDOP), Horizontal Dilution of Precision (HDOP), and Vertical Dilution of Precision (VDOP) are as follows:

[0026] PDOP 2 =VDOP 2 +HDOP 2

[0027] The distance observation equation between the UWB base station and the tag can be expressed as:

[0028]

[0029] In the above formula, D(r,t) is the distance between the base station and the tag; (x t ,y t ,z t (x) represents the coordinates of the UWB base station; t ,y t ,z t () represents the label coordinates;

[0030] The above observation equation is obtained by expanding the approximate coordinates (x0, y0, z0) into a Taylor series using the approximate coordinates as the median. The three-axis deviations between the true and approximate coordinates of the label are (△x, △y, △z).

[0031]

[0032] Ignoring components of second order and above, the bias component is:

[0033]

[0034] In the above formula, This is an approximate distance calculated using base station coordinates and approximate tag coordinates;

[0035] The base station observation equation can be transformed into a matrix expression as follows:

[0036] Δd=HΔX

[0037] The observation matrix H in the observation equation is:

[0038]

[0039] In the above formula, Let x, y, and z represent the direction cosines of the UWB base station in the x, y, and z directions, respectively; from this, the error covariance matrix can be calculated:

[0040]

[0041] In the above formula, Q ij Let represent the covariance between the i-th and j-th observations. The formula for calculating the plane precision factor is as follows:

[0042]

[0043] The formula for calculating the vertical accuracy factor is:

[0044]

[0045] The formula for calculating the position accuracy factor is:

[0046]

[0047] Currently, commonly used UWB base stations and tags employ bidirectional communication for distance measurement, thus eliminating the need to consider synchronization issues between them. Based on this, the distance between the UWB base station and the tag can be obtained as follows:

[0048]

[0049] In the above formula, Where is the distance between the UWB base station and the positioning tag, c is the speed of light, t is the signal propagation time, and ε is the error term, including other errors such as multipath propagation, which is approximately on the order of centimeters.

[0050] Furthermore, the specific method of step S4 also includes:

[0051] Due to the limitations of UWB base station transmit power, each base station has a distance constraint on its signal coverage range, namely:

[0052]

[0053] In the above formula, L is the maximum signal reception distance within the coverage area of ​​the UWB base station;

[0054] When all UWB base stations are aligned in a straight line, an ill-conditioned network is formed. Deploying UWB base stations in a straight line is not suitable for 3D positioning. It is necessary to calculate the area of ​​a triangle using Heron's formula to determine whether the base stations are aligned in a straight line, thereby constraining the deployment of UWB base stations.

[0055]

[0056]

[0057] In the above formula, a, b, and c are the three side lengths of the triangle, p is half the perimeter of the triangle, and S is the area of ​​the triangle.

[0058] In indoor environments, the area where base stations can be deployed is subject to spatial constraints, namely:

[0059] X min ≤X n ≤X max ,Y min ≤Y n ≤Y max Z min ≤Z n ≤Z max .

[0060] Furthermore, the optimal mathematical model for deploying multiple UWB base stations is as follows:

[0061]

[0062] Furthermore, the specific method for constructing the optimal mathematical model for multi-UWB single base station deployment is as follows:

[0063] Single-station positioning technology based on angle and distance measurement obtains the elevation angle α and horizontal angle β using a UWB array via a combined amplitude-phase angle measurement method. Then, the distance d between the base station and the target node is calculated using a two-way distance measurement method. Assuming the base station coordinates are (x... S ,y S ,z S The actual position of the label T is (x T ,y T ,z T The coordinates T' calculated from the label observations can be expressed as:

[0064]

[0065] The positioning error can be obtained by subtracting the actual position from the position calculated from the observed values.

[0066]

[0067] Therefore, the measurement error of a single UWB base station is:

[0068]

[0069] Furthermore, the mathematical model for the optimal design of a single UWB base station deployment is as follows:

[0070]

[0071] In the above formula, N represents the number of grid points in the location service area, and Φ represents the three-dimensional positioning error of a single UWB base station in the location service area.

[0072] The beneficial effects of this invention are:

[0073] This invention reads indoor 3D model information and automatically identifies open and narrow environments based on the read 3D model, identifying the base station deployment area and the positioning service area. For open environments, multi-site UWB deployment is selected, while for narrow environments, single-site UWB deployment is selected. Based on different base station detection distance limits, UWB base station network optimization is performed only within the area of ​​the base station detection distance limit, effectively optimizing the network structure and improving UWB positioning accuracy. In open environments, the optimized UWB base station network structure shows a certain improvement in the average PDOP value within the positioning area compared to networks deployed based solely on experience, and the average positioning accuracy of the selected target points is significantly improved. In narrow environments, multi-site UWB networks generally exhibit ill-formed structures due to environmental limitations; therefore, this invention uses single-site UWB for optimized network deployment in narrow environments. This invention optimizes the network structure of both multi-site and single-site UWB, improving positioning accuracy in the positioning area while ensuring minimal cost. Attached Figure Description

[0074] Figure 1 This is a flowchart illustrating the multi-station or single-station UWB positioning network optimization method provided by the present invention.

[0075] Figure 2 This is an indoor three-dimensional scene diagram of a specific embodiment of the present invention;

[0076] Figure 3 This is a schematic diagram of another specific embodiment of the present invention;

[0077] Figure 4 This is a diagram showing the distribution of accuracy factors in the indoor positioning area under the optimized mesh pattern of the present invention.

[0078] Figure 5 This is another embodiment of the accuracy factor distribution results of the indoor positioning area under the optimized mesh pattern of the present invention;

[0079] Figure 6This is another embodiment of the accuracy factor distribution result of the indoor positioning area under the optimized mesh pattern of the present invention, as shown in the figure.

[0080] Figure 7 This is a flowchart of a three-dimensional network optimization method for UWB base stations based on a closed space model according to the present invention. Detailed Implementation

[0081] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0082] Reference Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 The method for optimizing the three-dimensional network topology of UWB base stations based on a closed space model, as shown, includes the following steps:

[0083] S1, UWB Base Station Attribute Input: Responsible for obtaining UWB base station equipment information, including the base station's antenna height, the effective coverage distance of the base station signal, and important parameters of angle measurement error, thereby realizing the instantiation of ranging UWB base stations and ranging and angle-measuring UWB base stations.

[0084] In this embodiment, the basic data input is responsible for acquiring base station equipment information, including important parameters such as antenna height and model. When deploying the base station, antenna height needs to be fully considered, and the maximum coverage area of ​​the base station signal needs to be obtained based on the model. Meanwhile, the 3D model information reading unit is mainly used to extract data such as the selected positioning area boundary, base station deployment range, and indoor terrain.

[0085] The basic data input part of this invention is achieved by reading 3D models in .OBJ format, automatically reading relevant information from the model and classifying and storing it.

[0086] S2. Location Scene Digital Model Input and Recognition: By reading the three-dimensional digital model of the enclosed space in OBJ format, the system automatically reads relevant information from the model and extracts the location area boundary, base station deployment range, and terrain data; Model Component Recognition: The system reads and recognizes the entity information of the interior walls, ceiling, floor, and columns of the read indoor three-dimensional model.

[0087] In this embodiment, Table 1 provides information on the relevant OBJ format digital model files.

[0088] Table 1: Basic prefixes for OBJ format digital model files

[0089]

[0090] S3. Identify the scene type and determine the positioning method. If the actual scene is an open environment, the ranging UWB multi-base station positioning mode is adopted, which has high accuracy. If the actual scene is a narrow and elongated scene, the ranging and angle-measuring UWB single-base station positioning mode is adopted. This overcomes the pathological network problem of multi-base stations.

[0091] S4. Construct an optimal mathematical model for the deployment of multiple UWB base stations.

[0092] S5. Construct an optimal mathematical model for the deployment of multiple UWB single base stations.

[0093] This invention addresses the complexity of enclosed spaces such as indoor and underground environments by optimizing the deployment of multi-range UWB base stations in open areas and single-range and angle-measuring UWB base stations in narrow and elongated areas based on digital models of actual scenarios. This achieves precise location determination of UWB base stations and improves the overall positioning effect.

[0094] Furthermore, the specific method of step S4 includes:

[0095] After obtaining the reference coordinates of the location service area through the digital model, the reference coordinates of the service area are transformed into a local coordinate system;

[0096] The transformation formula between the local coordinate system and the reference coordinate system is as follows:

[0097]

[0098] In the above formula, (X l ,Y l (X) represents the local coordinates of a ground grid point. g ,Y g (X) represents the reference coordinates of the ground grid points. o ,Y o () represents the reference coordinates of the origin of the local coordinate system. This is the rotation angle between the local coordinate system and the reference coordinate system.

[0099] In this embodiment, the three-dimensional model is used to define the service area grid. After obtaining the reference coordinates of the service area through the three-dimensional model, the reference coordinates of the service area are first transformed into a local coordinate system to facilitate the division of the three-dimensional and two-dimensional planar grids. During this process, a grid is established with the southwest corner point of the first-floor lobby service area (e.g.,...) as the reference coordinate system. Figure 3 (a) is a local coordinate system with the lower left corner as the origin, where the north direction is defined as the x-axis and the east direction as the y-axis, and the unit length adopts the meter (m) in the International System of Units.

[0100] Furthermore, the specific method of step S4 includes:

[0101] The location service area is divided into N equal-sized two-dimensional grids W by selecting gridded sampling points. i =xy, i=1,2…N, the label position is located on a two-dimensional grid point; the grid size of the positioning area is defined according to different requirements.

[0102] In this embodiment, after obtaining the local coordinates of the service area, since PDOP can measure the positioning accuracy of any point within the service area, the positioning area is divided into N equal-sized two-dimensional grids W. i =xy, i=1,2…N, and the base station deployment area is divided into a three-dimensional grid of the same size, E i =xyz, i=1,2…N, where the UWB base station location and tag location are located on 3D grid points and 2D grid points respectively. The grid point locations can be obtained using a 3D model. For example... Figure 3 As shown in Figure a, the ground service area is divided into a 0.5m × 0.5m two-dimensional planar grid, totaling 625 two-dimensional planar grid points, as follows. Figure 3 As shown in Figure b, the space 2m above the ground service area in the vertical direction is divided into a 3m×3m×1m three-dimensional grid, with a total of 50 three-dimensional grid points.

[0103] Furthermore, the specific method of step S4 also includes:

[0104] The deployment area for UWB base stations is selected and divided into a three-dimensional grid of equal size. i =xyz, i = 1, 2…N, the UWB base station location is located on a three-dimensional grid; the grid size of the base station deployment area is defined according to different requirements. The grid size of the base station deployment area and the positioning area are defined according to different accuracy requirements.

[0105] Furthermore, the specific method of step S4 also includes:

[0106] The Depth of Precision (DOP) is an evaluation metric for multi-site UWB deployments under different network topologies, indicating varying positioning accuracy for the same 3D spatial target. DOP reflects positioning accuracy, and the DOP value reflects the performance of multi-site UWB under different network topologies. A smaller DOP value indicates a relatively uniform geometric distribution of base stations and better performance; conversely, a larger DOP value indicates a poorer geometric layout of base stations.

[0107] The base station type is defined, and the read indoor 3D model is identified. In typical open indoor environments, multi-station UWB positioning offers high accuracy. However, in narrow environments, multi-station UWB suffers from ill-defined network patterns, necessitating the use of single-station UWB. Therefore, multi-station UWB and single-station UWB networks are deployed for open and narrow environments, respectively.

[0108] In this embodiment, multi-station UWB deployments under different network topologies achieve varying positioning accuracies for the same three-dimensional spatial target. DOP represents the error magnification factor.

[0109] The optimal mesh layout is obtained by comparing the minimum DOP under different mesh shapes. The definition of DOP is:

[0110] DOP = σ p / σ m

[0111] In the above formula, σ p For the user's location error, σ m For measurement error;

[0112] The relationships between the Position Dilution of Precision (PDOP), Horizontal Dilution of Precision (HDOP), and Vertical Dilution of Precision (VDOP) are as follows:

[0113] PDOP 2 =VDOP 2 +HDOP 2

[0114] The PDOP value reflects the performance of multi-site UWB under different network topologies. Therefore, the optimal network topology of base stations can be studied by observing changes in the PDOP value. A smaller PDOP value indicates a relatively uniform geometric distribution of base stations and better performance; conversely, a larger PDOP value indicates a poorer geometric layout of base stations. In UWB indoor positioning systems, a uniform distribution of UWB base stations is beneficial for positioning calculation.

[0115] The distance observation equation between the UWB base station and the tag can be expressed as:

[0116]

[0117] In the above formula, D(r,t) is the distance between the base station and the tag; (x t ,y t ,z t (x) represents the coordinates of the UWB base station; t ,y t ,z t () represents the label coordinates.

[0118] The above observation equation is obtained by expanding the approximate coordinates (x0, y0, z0) into a Taylor series using the approximate coordinates as the median. The three-axis deviations between the true and approximate coordinates of the label are (△x, △y, △z).

[0119]

[0120] Ignoring components of second order and above, the bias component is:

[0121]

[0122] In the above formula, This is an approximate distance calculated using base station coordinates and approximate tag coordinates;

[0123] The base station observation equation can be transformed into a matrix expression as follows:

[0124] Δd=HΔX

[0125] The observation matrix H in the observation equation is:

[0126]

[0127] In the above formula, Let x, y, and z represent the direction cosines of the UWB base station in the x, y, and z directions, respectively; from this, the error covariance matrix can be calculated:

[0128]

[0129] In the above formula, Q ij Let represent the covariance between the i-th and j-th observations. The formula for calculating the plane precision factor is as follows:

[0130]

[0131] The formula for calculating the vertical accuracy factor is:

[0132]

[0133] The formula for calculating the position accuracy factor is:

[0134]

[0135] Currently, commonly used UWB base stations and tags employ bidirectional communication for distance measurement, thus eliminating the need to consider synchronization issues between them. Based on this, the distance between the UWB base station and the tag can be obtained as follows:

[0136]

[0137] In the above formula, Where is the distance between the UWB base station and the positioning tag, c is the speed of light, t is the signal propagation time, and ε is the error term, including other errors such as multipath propagation, which is approximately on the order of centimeters.

[0138] Furthermore, the specific method of step S4 also includes:

[0139] Due to the limitations of UWB base station transmit power, each base station has a distance constraint on its signal coverage range, namely:

[0140]

[0141] In the above formula, L is the maximum signal reception distance within the coverage area of ​​the UWB base station.

[0142] When all UWB base stations are aligned in a straight line, an ill-conditioned network is formed, making a linear deployment of UWB base stations unsuitable for 3D positioning. To address this issue, the area of ​​a triangle is calculated using Heron's formula to determine if the base stations are aligned, thus constraining the placement of UWB base stations.

[0143] When all UWB base stations are aligned in a straight line, the accuracy factor calculation for 3D positioning within the service area will fail due to the linear network. This is because a linear distribution of UWB base stations creates an ill-conditioned network. In this case, the matrix approaches singularity, making the normal equations invertible and thus preventing the calculation of the location accuracy factor. This indicates that deploying UWB base stations in a straight line is unsuitable for 3D positioning. To address this issue, the area of ​​a triangle can be calculated using Heron's formula to determine if the base stations are aligned in a straight line, thereby constraining the deployment of UWB base stations.

[0144]

[0145] In the above formula, a, b, and c are the three side lengths of the triangle, p is half the perimeter of the triangle, and S is the area of ​​the triangle.

[0146] In indoor environments, the area where base stations can be deployed is subject to spatial constraints, namely:

[0147] X min ≤X n ≤X max ,Y min ≤Y n ≤Y max Z min ≤Z n ≤Z max .

[0148] Furthermore, the optimal mathematical model for deploying multiple UWB base stations is as follows:

[0149]

[0150] In optimized network configurations, the overall PDOP value within the base station network area is relatively small. However, in the external area of ​​the base station network, the average PDOP value increases with the distance between the tag location and the base station. The PDOP value reaches its maximum at the four corners of the service area. For rectangular network configurations, the PDOP value is larger in the central area, exhibiting a cross-shaped distribution. The PDOP value is also relatively large at the midpoints of the four sides of the service area.

[0151] Furthermore, the specific method for constructing the optimal mathematical model for multi-UWB single base station deployment is as follows:

[0152] Since a single UWB base station only requires one base station to achieve positioning, the PDOP value cannot be used to evaluate positioning performance. Instead, the positioning error of a single UWB base station is used to evaluate the base station deployment performance in three-dimensional space by combining the ranging error and the angle measurement error.

[0153] Single-station positioning technology based on angle and distance measurement obtains the elevation angle α and horizontal angle β using a UWB array via a combined amplitude-phase angle measurement method. Then, the distance d between the base station and the target node is calculated using a two-way distance measurement method. Assuming the base station coordinates are (x... S ,y S ,z S The actual position of the label T is (x T ,y T ,z T The coordinates T' calculated from the label observations can be expressed as:

[0154]

[0155] The positioning error can be obtained by subtracting the actual position from the position calculated from the observed values.

[0156]

[0157] Therefore, the measurement error of a single UWB base station is:

[0158]

[0159] Furthermore, the mathematical model for the optimal design of a single UWB base station deployment is as follows:

[0160]

[0161] In the above formula, N represents the number of grid points in the location service area, and Φ represents the three-dimensional positioning error of a single UWB base station in the location service area.

[0162] In this embodiment, based on the UWB single base station, the optimal deployment location is determined to be a straight line along the y=2.5m direction, with a 0.5m grid size deployed horizontally. Simulation experiments and analysis were conducted, and the average positioning error within the positioning area under the optimized UWB single base station network in a narrow environment was 0.1688m.

[0163] The propagation model is determined based on the selected base station type and deployment method, defining the various required or optional parameters.

[0164] Execute the selected propagation model, perform the actual calculations, and return the results.

[0165] The display shows the base station locations, positioning area accuracy factors, and positioning error distribution maps used to generate the optimal network shape.

[0166] The output of this invention automatically generates a corresponding results folder, including base station coordinates, position accuracy factor values ​​of each grid point in the positioning area, positioning error, etc.

[0167] By adopting the above-disclosed technical solution of this invention, the following beneficial effects are obtained:

[0168] This invention is divided into four modules: basic data input, optimized layout, data processing, and scene display. The basic data input module reads information such as vertex coordinates, materials, and triangular faces of components in the 3D model. The optimized layout module determines the optimal layout scheme by designing variables, setting objective functions, and establishing constraints. The data processing module uses the 3D model information obtained from the basic data input module to automatically identify the positioning area and the base station deployment area and divide it into a grid. The positioning area is divided into a two-dimensional planar grid, and the base station deployment area is divided into a three-dimensional solid grid. The positioning base station uses a traversal optimization module to iteratively traverse the points of the three-dimensional solid grid to calculate the positioning area, obtain all possible layout schemes, and select the optimal layout scheme by calculating the position accuracy factor value or positioning error evaluation index. The scene display can display the positioning accuracy distribution map of the generated optimal layout scheme and the 3D scene including the positioning base station.

[0169] This invention employs multi-station and single-station UWB network optimization algorithms, which can be widely applied to point-to-point and point-to-multipoint indoor positioning signal wireless propagation related calculations, and can accurately simulate whether the base station and the sampling point can receive the signal.

[0170] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1.A method for three-dimensional mesh optimization of UWB base stations based on a closed space model, characterized in that, Comprise the following steps: S1, UWB base station attribute input: responsible for obtaining UWB base station device information, including the antenna height of the base station, the effective coverage distance of the base station signal, the angle measurement error important parameter, so as to realize the instantiation of the ranging UWB base station and the ranging and angle measurement UWB base station; S2, positioning scene digital model input and identification: by reading the three-dimensional digital model of the closed space, OBJ format is realized, the related information in the model is automatically read and the positioning area boundary, base station layout range and terrain data are extracted;The identification of model components reads and identifies the wall, ceiling, floor and column entity information in the read indoor three-dimensional model; S3, identify scene type and determine positioning mode, if the actual scene is open environment, then adopt the ranging UWB multi-base station positioning mode, which has high precision;If the actual scene is a narrow scene, then adopt the ranging and angle measurement UWB single base station positioning mode; S4, construct the optimal mathematical model of multi-UWB base station layout; S5, construct the optimal mathematical model of multi-UWB single base station layout; The specific method of step S4 comprises: After obtaining the reference coordinates of the positioning service area through the three-dimensional digital model, the reference coordinates of the service area are converted into a local coordinate system; The conversion formula of the local coordinate system and the reference coordinate system is: ； In the above formula, (X l ,Y l ) is the local coordinate of the ground grid point, (X g ,Y g ) is the reference coordinate of the ground grid point, (X o ,Y o ) is the reference coordinate of the origin of the local coordinate system, and φ is the rotation angle between the local coordinate system and the reference coordinate system. The specific method of step S4 comprises: The positioning service area is gridded and sampling points are selected, and the positioning area is divided into N two-dimensional grids W of the same size i = (X i , Y i ), i = 1, 2…N, and the tag position is located on the two-dimensional grid point; the grid size of the positioning area is defined according to different requirements; The specific method of step S4 further comprises: The UWB base station can be arranged in an area selected from a three-dimensional grid of the same size, E i = (X i , Y i , Z i ), i = 1, 2…N, and the position of the UWB base station is located on the three-dimensional grid point; the grid size of the base station arrangement area is defined according to different requirements; The specific method of step S4 further comprises: The DOP of the evaluation index space position accuracy factor, the multi-station UWB has different positioning accuracy for the same three-dimensional space positioning target under different network shapes; The optimal layout network shape is obtained by comparing the minimum value of DOP under different network shapes, and the definition of DOP is as follows: DOP = σ p / σ m In the above equation, σ p is the user position error, σ m is the measurement error; The relationship between the space position accuracy factor (Position Dilution of Precision PDOP), the plane accuracy factor (Horizonal Dilution of Precision, HDOP) and the vertical accuracy factor (Vertical Dilution of Precision, VDOP) is as follows: PDOP 2 = VDOP 2 + HDOP 2 The distance observation equation between the UWB base station and the tag can be expressed as: ； In the above formula, D(r, t) is a distance value between the base station and the tag; (x r ,y r ,z r ) is a UWB base station coordinate; (x t ,y t ,z t ) is a tag coordinate; The above observation equation is the Taylor series expansion with the approximate coordinates (x0, y0, z0) as the median, and the three-axis deviation of the real coordinates and the approximate coordinates of the tag is (△x, △y, △z), then ； Neglecting the components above the second order, the deviation component is: ； In the above formula, is a distance approximation calculated using base station coordinates and tag approximate coordinates; is a distance between the UWB base station and the positioning tag; The base station observation equation is converted into matrix expression as follows: Δd=HΔX The observation matrix H in the observation equation is: ； In the above formula, respectively represent the direction cosine of the UWB base station in the x, y, z three directions; thus the error covariance matrix can be obtained: ； In the above formula, Q ij The covariance of the ith observation and the jth observation is represented by Qij, and the calculation formula of the plane precision factor is as follows: ； The calculation formula of the vertical accuracy factor is: ； The calculation formula of the position accuracy factor is: ； The UWB base station and the tag adopt two-way communication for ranging, so it is not necessary to consider the synchronization problem between the UWB base station and the tag;Based on this, the distance between the UWB base station and the tag can be obtained as follows: ； In the above formula, is the distance between the UWB base station and the positioning tag, c is the speed of light, t is the time of signal propagation, ε i is an error term, including multipath error; The specific method of step S4 further comprises: The constraint condition, due to the limitation of the transmission power of the UWB base station, each base station has a distance constraint of signal coverage range, that is: ； In the above formula, L is the maximum distance of signal reception within the coverage range of the UWB base station. When all UWB base stations are in the same straight line, a sick net shape is formed, and the UWB base stations are not suitable for three-dimensional positioning in the form of a straight line; the position of the base station whether in the same straight line is judged by calculating the area of the triangle through the Heron formula, so as to constrain the layout position of the UWB base station: ； In the above formula, a, b, c are the lengths of the three sides of the triangle, p is half the perimeter of the triangle, and S is the area of the triangle; In the indoor environment, the space constraint exists in the base station layout area, and the constraint is: X min ≤ X n ≤ X max Y min ≤ Y n ≤ Y max Z min ≤ Z n ≤ Z max ; The optimal mathematical model of the multi-UWB base station layout is: ； The specific method for constructing the optimal mathematical model of the multi-UWB single base station layout is: The single station positioning technology based on angle measurement and distance measurement is to obtain the pitch angle a and the horizontal angle b by the amplitude-phase joint angle measurement method through the UWB array, and then obtain the distance d between the base station and the node to be measured by the two-way distance measurement method. Assuming that the coordinates of the base station are (x S ,y S ,z S ), the real position of the tag T is (x T ,y T ,z T ), and the tag observation value solving coordinate T' can be expressed as: ； The positioning error can be obtained by subtracting the true position from the position obtained by solving the observation value: ； Further, the measurement error of the UWB single base station is: ； The optimal mathematical model of the multi-UWB single base station layout is: ； In the above formula, N represents the number of grid points in the positioning service area, and Φ represents the three-dimensional positioning error of the UWB single base station in the grid point in the positioning service area. It also includes: a propagation model for determining the propagation model according to the selected base station type and the layout mode of the base station, and defining various necessary or optional parameters required by it; An execution module for selecting the propagation model to perform actual calculation and return the results thereof; A display module for displaying the base station position of the generated optimal net shape, the positioning area accuracy factor and the positioning error distribution map; An output module for automatically generating a corresponding result folder, including base station coordinates, positioning area grid point position accuracy factor values and positioning errors.

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