UWB-based narrow channel switching positioning method and system

Abstract

The invention discloses a UWB-based narrow channel switching positioning method and system, and the method comprises the steps: employing a UWB communication technology, achieving the real-time distance calculation of a base station and a UWB tag module through employing an improved TWR distance measurement method, obtaining the real-time position of the UWB tag module through the distance information through employing a robust multi-base-station algorithm, and carrying out the switching positioning of a narrow channel. When the NLOS environment is serious, high-precision positioning, base station switching and fault abnormal base station elimination are completed; a base station number corresponds to a positioning sub-area number, an upper computer module stores a positioning system configuration table into a UWB tag module, the UWB tag module carries out ranging polling with a corresponding UWB base station module according to the positioning sub-area, and all resolving is completed by the UWB tag module; according to the method disclosed by the invention, only the UWB base station module is required to perform UWB information receiving and transmitting functions, so that the number of base stations can be infinitely expanded while the endurance

Description

Technical Field

[0001] The present invention relates to the technical field of mobile wireless communication and location-based services, and in particular to a narrow channel switching positioning method and system based on UWB. Background Art

[0002] With the continuous development of artificial intelligence and industrial Internet technologies, the positioning information of indoor people and objects has become very important, especially in severe NLOS environments such as narrow passages. At present, wireless technologies such as Bluetooth, WiFi, and RFID are mostly used to achieve position positioning, but these traditional positioning methods have poor positioning accuracy and cannot meet the requirements of high-precision positioning.

[0003] Ultra Wide Band (UWB) technology is a wireless carrier communication technology that does not use a sinusoidal carrier but uses nanosecond non-sinusoidal narrow pulses to transmit data, so it occupies a wide spectrum range. UWB technology has the advantages of low system complexity, low power spectrum density of transmitted signals, insensitivity to channel fading, low interception capability, and high positioning accuracy. However, conventional UWB positioning systems are positioning systems with a fixed number of base stations, with limited coverage, and the conventional three-side positioning algorithm used has a significant impact on positioning accuracy in environments with severe NLOS.

[0004] The existing UWB positioning systems have the following defects:

[0005] (1) In the process of positioning and solving, only the common three-sided positioning algorithm is used, without considering the impact of non-line-of-sight ranging error on the position information solution, and no visualization host computer is designed to facilitate real-time observation;

[0006] (2) It is only used to determine the area where the current tag is located, without switching base stations, and the obtained coordinates are one-dimensional, which is difficult to expand to two-dimensional positioning. The tag performs real-time position calculation, which increases the power consumption of the tag;

[0007] (3) When using the traditional three-sided positioning algorithm and not considering the NLOS situation, the positioning accuracy will decrease, and the base stations are divided into master and slave base stations, which increases the communication complexity. Summary of the invention

[0008] Purpose of the invention: In order to solve the problems of small positioning coverage, high base station energy consumption, poor positioning accuracy, abnormal fault conditions, etc. in the existing UWB positioning system, the present invention proposes a narrow channel switching positioning method and system based on UWB, which realizes accurate and high-stability positioning.

[0009] Technical solution: A narrow channel switching positioning method based on UWB, comprising the following steps:

[0010] Step 1: Divide the area to be positioned into multiple positioning sub-areas, each positioning sub-area has one and only one positioning sub-area number, deploy several UWB base station modules in the area to be positioned, each UWB base station module has one and only one base station ID number, so that two adjacent positioning sub-areas share two UWB base station modules; the union of all positioning sub-areas is the area to be positioned, and the area of ​​the intersection of all positioning sub-areas is an empty set; correspond each positioning sub-area number with the base station ID number of the UWB base station module it contains to form a positioning system configuration table; store the positioning system configuration table and the three-dimensional coordinates of each UWB base station module in the host computer module;

[0011] Step 2: Use the stationary UWB tag module to perform ranging polling on all UWB base station modules in the positioning area to obtain the real-time distance information of all UWB base station modules. The stationary UWB tag module packages all the obtained real-time distance information and the corresponding base station ID number and sends them to the host computer module;

[0012] Step 3: The host computer module performs positioning and solving according to all the real-time distance information and the three-dimensional coordinates of the UWB base station module corresponding to the base station ID number, obtains the coordinate information of the stationary UWB tag module, and determines the positioning sub-area number of the positioning sub-area where the stationary UWB tag module is currently located. The host computer module packages the positioning system configuration table, the three-dimensional coordinates of each UWB base station module, and the positioning sub-area number of the positioning sub-area where the stationary UWB tag module is currently located and sends them to the UWB tag module;

[0013] Step 4: When the UWB tag module moves in the positioning sub-area, the UWB tag module determines the base station ID number that needs to be polled for ranging according to the received positioning sub-area number by comparing the positioning system configuration table, and completes ranging with one UWB base station module at a time in sequence. After completing the ranging polling of all UWB base station modules in the positioning sub-area, the distance information of all UWB base station modules in the positioning sub-area is obtained; the distance information of the UWB base station module includes RSSI;

[0014] Step 5: The UWB tag module obtains the RSSI of all UWB base station modules in the positioning sub-area, compares the RSSI with the threshold, removes the distance information with RSSI lower than the threshold, and performs positioning calculation on the remaining distance information in combination with the three-dimensional coordinates of the corresponding UWB base station module to obtain the real-time location information of the UWB tag module;

[0015] Step 6: The UWB tag module performs filtering processing on the obtained real-time location information of the UWB tag module to obtain the real-time location of the tag;

[0016] Step 7: The UWB tag module uploads the real-time distance and real-time location information of the tag of this ranging polling to the upper computer module; at the same time, the UWB tag module determines whether the current positioning sub-area of ​​the UWB tag module is switched with the positioning sub-area of ​​the previous round of ranging polling according to the real-time location of the tag. If a switch occurs, the positioning system configuration table is checked to determine which UWB base station modules the UWB tag module needs to poll with in the next ranging cycle, and step 4 is executed; if no switch occurs, the next UWB base station module is ranged in sequence;

[0017] Step 8: The host computer module determines whether there is a missing UWB base station module by comparing the distance information of all UWB base station modules uploaded by the UWB tag module with the ID number. If so, a fault alarm is issued; the host computer module uses cluster analysis to determine whether there is an abnormal UWB base station module based on the distance information of all uploaded UWB base station modules; the host computer module only packages the base station ID number of the faulty missing UWB base station module and the base station ID number of the abnormal UWB base station module and sends them to the UWB tag module. The UWB tag module removes the base station ID number of the missing UWB base station module and the base station ID number of the abnormal UWB base station module in the next round of ranging.

[0018] The present invention also discloses a narrow channel switching positioning system based on UWB, comprising:

[0019] Several UWB base station modules are deployed inside the area to be located and used for ranging communication with the UWB tag modules;

[0020] The UWB tag module is used for moving in the positioning sub-area. The UWB tag module determines the base station ID number that needs to be polled for ranging according to the received positioning sub-area number by comparing the positioning system configuration table, and completes ranging with one UWB base station module at a time in sequence. After completing the ranging polling of all UWB base station modules in the positioning sub-area, the distance information of all UWB base station modules in the positioning sub-area is obtained; the distance information of the UWB base station module includes RSSI; and the UWB tag module is used to obtain the RSSI of all UWB base station modules in the positioning sub-area, compare the RSSI with a threshold, eliminate the distance information with RSSI lower than the threshold, and perform positioning and solution on the remaining distance information in combination with the three-dimensional coordinates of the corresponding UWB base station module to obtain the real-time position information of the UWB tag module. information; and the UWB tag module is used to filter the obtained real-time location information of the UWB tag module to obtain the real-time location of the tag; and the UWB tag module is used to upload the real-time distance of the current ranging polling and the real-time location information of the tag to the upper computer module; at the same time, the UWB tag module determines whether the current positioning sub-area of ​​the UWB tag module and the positioning sub-area of ​​the previous round of ranging polling are switched according to the real-time location of the tag. If switching occurs, the positioning system configuration table is checked to determine which UWB base station modules the UWB tag module needs to poll with in the next ranging cycle; if no switching occurs, the next UWB base station module is ranged in sequence; and the UWB tag module removes the base station ID number of the missing UWB base station module and the base station ID number of the abnormal UWB base station module in the next round of ranging;

[0021] The host computer module is used to store the positioning system configuration table and the three-dimensional coordinates of each UWB base station module, wherein the positioning system configuration table is composed of the correspondence between each positioning sub-area number and the base station ID number of the UWB base station module contained therein; and is used to perform positioning and solving according to all the original distance information obtained and the three-dimensional coordinates of the UWB base station module corresponding to the base station ID number, obtain the coordinate information of the stationary UWB tag module, and determine the positioning sub-area number of the positioning sub-area where the stationary UWB tag module is currently located, and the host computer module packages the positioning system configuration table, the three-dimensional coordinates of each UWB base station module and the positioning sub-area number of the positioning sub-area where the stationary UWB tag module is currently located and sends them to the UWB tag module; and is used to determine whether there is a missing UWB base station module according to the real-time distance of the current ranging polling, and if so, a fault alarm is issued; the host computer module uses cluster analysis according to the real-time distance of the current ranging polling to determine whether there is an abnormal UWB base station module; the host computer module only packages the base station ID number of the missing UWB base station module and the base station ID number of the abnormal UWB base station module and sends them to the UWB tag module;

[0022] Wherein, in the host computer module, all the original distance information and base station ID numbers are obtained by using a stationary UWB tag module to perform ranging polling on all UWB base station modules in the positioning area to obtain the original distance information of all UWB base station modules, and the stationary UWB tag module packages all the obtained original distance information and the corresponding base station ID numbers and sends them to the host computer module;

[0023] Among them, the positioning sub-area is obtained by dividing the area to be positioned, each positioning sub-area has one and only one positioning sub-area number, and several UWB base station modules are deployed in the area to be positioned. Each UWB base station module has one and only one base station ID number, so that two adjacent positioning sub-areas share two UWB base station modules; the union of all positioning sub-areas is the area to be positioned, and the area of ​​the intersection of all positioning sub-areas is an empty set.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0025] (1) In narrow channel positioning, the method of the present invention adopts UWB communication technology, uses the improved TWR ranging method to realize the real-time distance calculation between the base station and the UWB tag module, and uses the distance information to use the robust multi-base station algorithm to obtain the real-time position of the UWB tag module, and completes high-precision positioning, base station switching and faulty abnormal base station elimination when the NLOS environment is serious;

[0026] (2) The method of the present invention corresponds the base station number to the positioning sub-area number, and the host computer module stores the positioning system configuration table in the UWB tag module. The UWB tag module performs ranging polling with the corresponding UWB base station module according to the positioning sub-area, and all solutions are completed by the UWB tag module;

[0027] (3) In order to reduce the impact of NLOS, the present invention uses an RSSI-based robust multi-base station positioning algorithm, and the calculated location information of the UWB tag module is used as the input of the Hample filter. The Hample filter is used to eliminate abnormal mobile NLOS, and the filtered location information is used as the real-time location of the UWB tag module. By checking the positioning system configuration table, it is determined whether the next ranging polling needs to be switched, and if so, which UWB base station modules to poll;

[0028] (4) The host computer module of the present invention performs anomaly detection based on the distance measurement and location information of the UWB tag module using a K-Means clustering anomaly detection algorithm, detects whether a base station failure occurs, and sends the ID number of the faulty or abnormal base station to the UWB tag module; compared with the traditional positioning system, the method of the present invention effectively solves the problems of the conventional positioning system having a small positioning range in narrow channels, being greatly affected by the NLOS environment, and having poor positioning accuracy; at the same time, the method of the present invention only requires the UWB base station module to perform the UWB information receiving and sending functions, thereby improving the battery life and expanding the number of base stations indefinitely. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a structural block diagram of a narrow channel switching positioning system based on UWB proposed by the present invention;

[0030] Figure 2 This is a flow chart of the robust multi-base station positioning algorithm proposed by the present invention;

[0031] Figure 3 Schematic diagram of two possible situations of the robust positioning algorithm proposed by the present invention;

[0032] Figure 4 This is a communication diagram of the improved TWR bilateral two-way ranging algorithm proposed in the present invention;

[0033] Figure 5 A schematic diagram of the base station arrangement proposed by the present invention;

[0034] Figure 6 This is a flowchart of initializing the UWB tag module proposed by the present invention;

[0035] Figure 7 This is a flowchart of autonomous ranging, positioning and switching of the UWB tag module proposed in the present invention;

[0036] Figure 8 A schematic diagram of a base station before and after switching proposed by the present invention;

[0037] Fig. 9 This is a flowchart of troubleshooting abnormal faults of the host computer module proposed by the present invention;

[0038] Fig.10 This is a schematic diagram of the fault alarm of the host computer module proposed by the present invention. DETAILED DESCRIPTION

[0039] The technical solution of this embodiment is now further described in conjunction with the accompanying drawings.

[0040] Embodiment 1:

[0041] This embodiment proposes a narrow channel switching positioning method based on UWB. A narrow channel refers to a limited small space with a small scale, a long lateral distance and channel restrictions. The signal shielding in this environment will be more serious. Figure 1 As shown, the positioning method involves three modules: 2N UWB base station modules, a movable UWB tag module and a host computer module, which mainly includes the following steps:

[0042] Step 1: Distribute 2N UWB base station modules evenly and symmetrically on both sides of the narrow channel to form a rectangular total area. The narrow channel is divided into several positioning sub-areas. Each positioning sub-area is composed of 2M (N>M≥2) adjacent base stations. Each positioning sub-area does not overlap. The number of base stations in each positioning sub-area can be customized and adjacent positioning sub-areas share 2 repeated UWB base station modules to cover and meet positioning requirements. The movable UWB tag module is considered to be in the range when it moves in the positioning sub-area. Ensure that the union of all positioning sub-areas is the rectangular total area, and the area of ​​the intersection of the positioning sub-areas is an empty set.

[0043] The movable UWB tag module moves in each positioning sub-area; 2N UWB base station modules communicate with the movable UWB tag module using radio technology based on the IEEE 802.15.4a standard, and the movable UWB tag module completes wireless communication with the host computer module through the WIFI module.

[0044] Figure 5 An example of the UWB base station module mode is shown, dividing the narrow channel into three positioning sub-areas, positioning sub-area 1 includes four UWB base station modules, namely: UWB base station module 1, UWB base station module 2, UWB base station module 3 and UWB base station module 4; positioning sub-area 2 includes six UWB base station modules: UWB base station module 3, UWB base station module 4, UWB base station module 5, UWB base station module 6, UWB base station module 7 and UWB base station module 8; positioning sub-area 3 includes four UWB base station modules: UWB base station module 7, UWB base station module 8, UWB base station module 9 and UWB base station module 10, and each positioning sub-area shares 2 UWB base station modules.

[0045] The two-dimensional coordinates of each UWB base station module in the narrow channel are measured, and the host computer module corresponds each positioning sub-area number with the base station ID number of the UWB base station module it contains to form a positioning system configuration table; the positioning system configuration table and the two-dimensional coordinates of each UWB base station module in the narrow channel are saved to complete the host mechanism table and map construction operations. Since the UWB base station module only needs to complete TWR ranging with the UWB tag module, the endurance of the UWB base station module is increased, and the layout of multiple UWB base station modules can also increase the coverage of the positioning system.

[0046] Step 2: Power on the UWB base station module and UWB tag module to complete the initial settings of the UWB tag module. The specific operations include:

[0047] S2_1: The stationary UWB tag module performs ranging polling with 2N UWB base station modules. The UWB tag module calculates all distance information and packages all distance information with the corresponding base station ID number and sends it to the host computer module;

[0048] S2_2: The host computer module uses the positioning algorithm to solve the coordinate information of the stationary UWB tag module according to the distance information, the corresponding base station ID number and the two-dimensional coordinates of the UWB base station module, and obtains the positioning sub-area number where the stationary UWB tag module is currently located according to the coordinate information of the stationary UWB tag module and the positioning system configuration table, and packages the positioning system configuration table, the two-dimensional coordinates of the UWB base station module and the positioning sub-area number where the stationary UWB tag module is currently located and sends them to the UWB tag module;

[0049] S2_2: The UWB tag module receives the message sent by the host computer module, and obtains the ID number of the base station that needs to be polled for the next round of ranging by comparing it with the positioning system configuration table, completing the initial setting of the UWB tag module.

[0050] Figure 6 A flowchart showing the initial setup of the UWB tag module is shown. Figure 5 Taking the positioning system composed of as an example, after completing the base station coordinate initialization and the positioning sub-area division, the UWB tag module performs ranging polling with base stations 1-10, and the UWB tag module obtains all the distance information, and packages the distance information and the corresponding base station ID number to the host computer module. The host computer module uses the positioning algorithm to solve the coordinate information of the stationary UWB tag module, and queries the table to determine the current positioning sub-area number of the UWB tag module. The host computer module packages the table and the current positioning sub-area number of the UWB tag module and sends them to the UWB tag module. After receiving the above information, the UWB tag module queries the table to determine the base station ID and order for the next polling, and completes the initial setting of the tag.

[0051] The flowchart of the positioning algorithm mentioned in S2_2 is as follows Figure 2 As shown, it is determined based on the number of base stations involved in positioning, including:

[0052] (a) Multi-base station positioning algorithm based on pseudo-inverse: When the number of UWB base station modules involved in positioning is ≥ 4, a multi-base station positioning algorithm is used, based on the pseudo-inverse least squares algorithm. Since the state matrix is ​​overdetermined, the pseudo-inverse method is used, and the result obtained is the least squares best estimate;

[0053] (b) Three-side positioning algorithm based on inverse matrix: When the number of UWB base station modules involved in positioning = 3, the multi-base station positioning algorithm is used. Since the state equation is positive definite, the algorithm is based on the least squares method of the inverse matrix. The obtained least squares solution is the optimal solution after linear fitting.

[0054] For the multi-base station positioning algorithm based on pseudo-inverse and the three-side positioning algorithm based on inverse matrix, the following steps are roughly included:

[0055] Assume that the real-time position of the UWB tag module to be tested is (x, y, z), and the position coordinates of 2M base stations are known to be (x i ,y i ,z i ), the distance between the tag module and each base station is d i , then the following system of equations can be constructed:

[0056]

[0057] Subtract the first n-1 equations from the last one and express them in matrix form to get AX=B:

[0058]

[0059]

[0060] Define the error vector as:

[0061] δ=AX-B

[0062] When the sum of squared errors is minimized, X is the position coordinate of the desired label module.

[0063] Construct the function f(x):

[0064] f(x)=AX-B) T (AX-B)

[0065] Let the derivative of f(x) be 0, when A T When A is non-singular, we can solve:

[0066] X=(A T A) -1 A T b

[0067] Among them, A T A is the pseudo-inverse of the matrix being sought. + / Inverse Matrix A -1 , the host computer can use the singular value decomposition method to find the pseudo-inverse A + / Inverse Matrix A -1 , making the algorithm more stable.

[0068] (c) Robust positioning algorithm based on map information: When the number of UWB base station modules involved in positioning is 2, the robust positioning algorithm is used. The state matrix is ​​underdetermined, and the distance between the two base stations will result in two fuzzy solutions. It is necessary to judge based on map information or the Euclidean distance from the previous moment:

[0069] When only two base stations are involved in positioning, due to the lack of basic information, two possible coordinate points (x 11 ,y 11 )、(x 22 ,y 22 ), according to the different positions of the coordinate points, it can be divided into the following two cases:

[0070] Case 1: Based on map information; after the label module calculates the location coordinates, it can be judged based on the map information, where (x 11 ,y 11 ) is displayed outside the narrow channel range, then exclude it, then select (x 22 ,y 22 ) as the tag coordinates obtained by the robust multi-base station positioning algorithm;

[0071] Case 2: Based on the Euclidean distance; where (x0, y0) is the coordinate of the label module at the previous moment, assuming that (x 11 ,y 11 )、(x 22 ,y 22 ) are within the range, and it is impossible to judge whether they are within the channel range, then calculate (x0, y0) based on the coordinates (x0, y0) of the tag module at the previous moment. 11 ,y 11 )、(x 22 ,y 22 ) and (x0, y0) have Euclidean distances d1 and d2. If d1>d2, then choose (x 22 ,y 22 ) as the tag coordinates obtained by the robust multi-base station positioning algorithm;

[0072]

[0073]

[0074] Figure 3 The diagram below shows two cases of robust positioning algorithm: the right diagram shows the judgment based on map information, (x 11 ,y 11 ) is out of range, excluded, (x 22 ,y 22 ) is the tag coordinates obtained by the robust multi-base station positioning algorithm. The left picture shows the judgment based on the Euclidean distance with the location information at the previous moment, and selects (x 22 ,y22) are the tag coordinates obtained by the robust multi-base station positioning algorithm.

[0075] The multi-base station algorithm of this embodiment is a pseudo-inverse algorithm based on least squares. Compared with the traditional three-sided positioning algorithm, the least squares solution obtained can provide more accurate location information. The robust algorithm can obtain relatively correct location information when a base station fails and only two base stations are involved in the positioning solution. The robust multi-base station positioning algorithm increases the robustness and positioning accuracy of the positioning system.

[0076] Step 3: The UWB tag module enters the formal workflow. The distance calculation, position calculation, switching judgment and communication with the host computer module are all completed independently by the UWB tag module. The UWB module only needs to complete TWR (Two-Way-Ranging) bilateral two-way ranging polling with the UWB tag module.

[0077] like Figure 7 As shown, the formal workflow of the UWB tag module is divided into the following steps:

[0078] S3_1: When the UWB tag module moves in a certain positioning sub-area, it queries the positioning system configuration table according to the current positioning sub-area number to obtain which base station ID numbers need to perform TWR (Two-Way-Ranging) bilateral two-way ranging based on TOA (Time Of Arrive). The UWB tag module performs ranging communication with one UWB base station module at a time in a fixed order.

[0079] Figure 4 The general process of the TWR (Two-Way-Ranging) bilateral two-way ranging round based on TOA (Time Of Arrive) is shown. This embodiment adopts the TWR (Two-Way-Ranging) bilateral two-way ranging round based on TOA (Time Of Arrive). The difference from the conventional TWR ranging method is that before the ranging starts, the UWB tag module broadcasts a Broadcast message, and the ID number of the base station that needs to establish communication this time is packaged in the Broadcast message. The UWB base station module receives and analyzes the Broadcast message. The function of the Broadcast message is to establish a one-to-one connection between the UWB tag module and the UWB base station module that needs to establish communication, and complete the tag-base station one-to-one registration. If the base station ID number packaged in the Broadcast message is the same as the base station ID number of the UWB base station module itself, a TWR ranging communication is performed, that is, the Poll message, Response message and Final message are used to perform ranging polling.

[0080] See Table 1 for data frame description:

[0081] Table 1 Data frame description

[0082] Number of bytes Field Content Functional Description 1-2 Data frame header Flag to judge the start of data transmission 3 Packet Type Determine whether it is a base station or a tag data packet 4-5 PAN ID Determine sender or receiver 6-7 Destination Address Positioning base station ID 8-9 Source Address Positioning tag ID 10 load Check digit 11-100 Timestamp Timestamp and RSSI of base station or tag

[0083] TWR ranging includes three messages: Poll, Response, and Final to complete a one-to-one ranging. In particular, if the UWB tag module does not receive the Poll message sent by the UWB base station module within 3ms, the UWB base station module is considered to have failed and the ranging communication with the next UWB base station module is switched.

[0084] The UWB base station module sends a Poll message to the UWB tag module. The UWB base station module records the Poll message sending timestamp T1 and immediately enters the waiting state after sending. round1 The UWB tag module waits for the Response message sent by the UWB tag module within the time; the UWB tag module waits for receiving the Poll message. If the message is received and the frame header is determined to be a Poll message, the UWB tag module records the Poll message receiving timestamp T2;

[0085] The UWB tag module sends a Response message to the UWB base station module. After receiving the Poll message, the UWB tag module waits for T reply1 The UWB tag module records the timestamp T3 of the Response message and immediately waits for the message to be received. round2 The UWB base station module waits for the Final message sent by the UWB base station module within T round1 The UWB base station module receives and identifies the correct Response message within T4. If the UWB base station module does not receive and identify the correct Response message within T round1 If a Response message is received within the time limit, it is considered as a timeout, the current ranging polling is terminated and the next ranging polling is started again;

[0086] The UWB base station module sends a Final message to the UWB tag module. The Final message includes: RSSI, the timestamp recorded by the base station (T1, T4, T5) and the current UWB base station ID number. After receiving the Response message, the UWB base station module waits for T reply2 The UWB base station module records the Final message sending timestamp T5. If the UWB tag module is within T round2 The UWB base station module receives and identifies the correct Final message within T6. If the UWB tag module does not receive and identify the correct Final message within T7, the UWB base station module records the Final message reception timestamp T6. round2If a Final message is received within the time limit, it is considered as a timeout, the current ranging polling is terminated and the next ranging polling is started again;

[0087] The UWB tag module receives the Final message and combines the three timestamps T2, T3, and T6 of receiving the Poll message, sending the Response message, and receiving the Final message to calculate the distance information and complete the distance measurement. The specific formula is as follows:

[0088] T round1 =T4-T1

[0089] T round2 =T6-T3

[0090] T reply1 =T3-T2

[0091] T reply2 =T5-T4

[0092] Wherein, T1, T2, T3, T4, T5, and T6 timestamps represent the time when the UWB base station module Poll message is sent, the time when the UWB tag module Poll message is received, the time when the UWB tag module Response message is sent, the time when the UWB base station module Response message is received, the time when the UWB base station module Final message is sent, and the time when the UWB tag module Final message is received; T round1 Indicates the effective time period for the UWB base station module to wait for receiving the Response message after sending the Poll message. round2 Indicates the effective time period for the UWB tag module to wait for receiving the Final message after sending the Response message. reply1 Indicates the fixed time that the UWB tag module waits to send a Response message after receiving a Poll message, T reply2 Indicates the fixed time that the UWB base station module waits to send a Final message after receiving a Response message;

[0093] The TOA is calculated using the following process:

[0094]

[0095]

[0096]

[0097] Get the flight time T prop Calculation formula:

[0098]

[0099] The flight time is multiplied by the speed of light constant c to obtain the distance value, completing the entire distance measurement process:

[0100] Distance = T prop ×c

[0101] RSSI reflects the signal strength of the DWM1000 module during the current communication process. The DWM1000 module is a UWB transceiver module designed based on the DW1000 chip of Decawave. It is the core module for the communication between the tag and the base station. The signal strength can reflect the strength of the NLOS environment in the current environment to a certain extent. The RSSI is calculated by the DWM1000 module. Specifically, the calculatePower(float base, floatN, uint8_t pulseFrequency) and dwGetReceivePower(void). The calculatePower function is an auxiliary function that can calculate the received power. It is used to combine the signal propagation model (for example, based on the free space loss model) to evaluate the received power. It cooperates with the dwGetReceivePower function to verify whether the received power meets expectations, optimize parameter settings, and calculate the theoretical power value in combination with the input parameters. It is usually used to compare or correct with the actual power. The dwGetReceivePower function is used to obtain the signal power value received by the DWM100 module, and calculate the received signal power in combination with parameters such as signal strength and total received signal energy, which is used to evaluate the quality of the received signal. Through the calculation of the two functions, the RSSI information is stored in the Final message sent by the UWB base station module to the UWB tag module. The UWB tag module receives the Final message and performs a solution, and can synchronously obtain the signal strength of the current ranging polling.

[0102] S3_2: After completing the ranging polling of the UWB base station module in the positioning sub-area, the UWB tag module compares the calculated RSSI with the threshold, removes the distance information with RSSI lower than the threshold, selects the remaining distance information and combines it with the corresponding three-dimensional coordinates of the UWB base station module to use the robust multi-base station positioning algorithm for position analysis, and obtains the current position information of the UWB tag module in the current ranging polling;

[0103] In this step, the UWB tag module uses the RSSI sent by the UWB base station module to actively remove outliers according to the threshold, and uses the remaining distance information that has not been removed as the input of the robust multi-base station positioning algorithm. The UWB tag module uses RSSI to dynamically remove outliers to remove base station distance information that is more seriously affected by the dynamic NLOS environment during the current ranging polling, thereby increasing the positioning accuracy in narrow spaces. The robust multi-base station positioning algorithm based on RSSI outlier removal increases the robustness and positioning accuracy of the positioning system.

[0104] S3_3: The location information of the mobile UWB tag module is used as the input of the Hample filter, and online filtering is completed in the UWB tag module. The window length and threshold multiple of the filter can be set according to requirements. The smaller the length and the lower the threshold, the more sensitive the filter is to abnormal values. The filter replaces the detected abnormal values ​​with the median of the data in the window, and uses the filtered location information as the final real-time location information of the mobile UWB tag module to avoid NLOS and signal loss or jump problems that are easily caused by switching;

[0105] In this step, the UWB tag module uses the Hample filter to filter the calculated location information, removes outliers in the location information and replaces them reasonably, avoiding the coordinate jump problem caused by the superposition of coordinate error, ranging error and other factors when the tag switches areas, further increasing the robustness of the positioning system.

[0106] S3_4: The UWB tag module uploads the real-time distance obtained by the current ranging polling and the real-time location information of the UWB tag module calculated based on the distance and the base station coordinates to the host computer module.

[0107] At the same time, the UWB tag module determines the current positioning sub-area of ​​the UWB tag module according to the real-time position information of the final mobile UWB tag module and the positioning system configuration table; and determines whether the current positioning sub-area is switched with the positioning sub-area in the previous round:

[0108] If no handover occurs, the base station for the next polling does not change;

[0109] If a handover occurs, a table is looked up to determine which UWB base station modules need to be polled in the next ranging cycle.

[0110] In this step, the UWB tag module queries the positioning system configuration table based on the filtered location information to complete the autonomous switching of the positioning sub-area. The switching mechanism of the UWB tag module satisfies the seamless positioning when the positioning sub-area changes, and can also increase the scalability of the positioning system, greatly increasing the coverage of the positioning system without increasing the positioning delay.

[0111] Figure 8 This is a schematic diagram before and after the base station switching. It can be found that the tag module switches from area 1 to area 2. Therefore, the corresponding polling base stations need to be switched from 1, 2, 3, 4 to 3, 4, 5, 6 in sequence to complete a positioning base station switch.

[0112] Step 4: The host computer module saves the real-time distance obtained by the ranging polling uploaded by the UWB tag and the real-time location information of the UWB tag module calculated based on the distance and the base station coordinates, and performs fault detection to determine whether a base station failure has occurred and issue an alarm; the abnormal base station is judged based on the K-Means clustering anomaly detection algorithm to complete the abnormal elimination of the dynamic NLOS of the UWB tag module during the movement. The host computer module then displays the real-time coordinates and motion trajectory according to the real-time location information of the final mobile UWB tag module, as shown in the figure. Fig. 9 As shown, the specific steps are as follows:

[0113] S4_1: The host computer receives the real-time distance obtained by the current ranging polling sent by the UWB tag module and the real-time location information of the UWB tag module calculated based on the distance and the base station coordinates, and completes the data storage;

[0114] S4_2: The host computer completes the real-time display of the three-dimensional map according to the real-time position information of the UWB tag module obtained by the calculation, and displays the real-time motion trajectory of the UWB tag module or reproduces the historical motion trajectory;

[0115] S4_3: The host computer receives the real-time distance information obtained by the current ranging polling sent by the UWB tag module, and performs fault detection according to the base station ID number corresponding to the positioning sub-area where the UWB tag module is currently located in the positioning system configuration table, that is, checks whether the number of distance information received is consistent with the number of UWB base station modules corresponding to the positioning sub-area where the UWB tag module is currently located in the positioning system configuration table. The missing one is the UWB base station module that has failed, checks the ID number of the failed base station, and issues a fault alarm in the host computer module; completing fault detection facilitates the management of a large-scale positioning system;

[0116] S4_4: The tag uses a three-side positioning algorithm based on three base stations to calculate the location information, The location information is used as the input of the K-means clustering algorithm, and the cluster center is obtained after several iterations. The data set whose distance from the cluster center exceeds the specified threshold is regarded as an abnormal data set. The Q UWB base station modules whose corresponding base station ID numbers participating in positioning appear more than the threshold L are extracted from the output abnormal data set and removed. The abnormal base station ID is regarded as an abnormal UWB base station module with poor dynamic NLOS during the movement of the UWB tag module.

[0117] S4_5: The host computer module sends the base station ID number of the abnormal UWB base station module and the base station ID number of the faulty UWB base station module to the UWB tag module to complete the fault troubleshooting. The UWB tag module removes the above base station ID number from the polling in the next ranging polling, which can reduce the positioning error caused by the abnormal NLOS environment from the root. Fig.10 This is a schematic diagram of the host computer fault alarm. When the UWB tag module is in the positioning sub-area 2, when performing ranging polling with UWB base station module 3, UWB base station module 4, UWB base station module 5, and UWB base station module 6, UWB base station module 5 fails. After the host computer module detects the fault, it issues a fault alarm and stops the ranging process with UWB base station module 5 in the next ranging polling.

[0118] The host computer module involved in this embodiment not only meets the functions of conventional data storage and real-time display of motion trajectory, but also detects possible base station failures and abnormal conditions that may be caused by NLOS environment based on the original data obtained by the host computer, and detects whether a base station failure has occurred by comparing the table information; uses the K-Means clustering-based anomaly detection algorithm to calculate the ID number of the base station seriously affected by NLOS according to the threshold comparison of the abnormal data set, and informs the UWB tag module of the ID number of the faulty and abnormal base station. The host computer fault and anomaly detection algorithm relies on the powerful computing power of the host computer to more accurately calculate the unstable base station, which serves as the basis for the positioning solution of the UWB tag module, and can further improve the robustness and positioning accuracy of the positioning system in a narrow NLOS environment.

[0119] In summary, in this embodiment, the UWB tag module performs ranging polling on the UWB base station module corresponding to the positioning sub-area, and uses the RSSI-based robust multi-base station algorithm to calculate the real-time position information of the UWB tag module. After passing through the Hample filter, the filtered data is used as the real-time position, and the positioning system configuration table is compared to decide whether to switch the polling base station. The above-mentioned ranging, positioning, and switching are all solved and decided in the UWB tag module. The host computer module uses the K-Means clustering anomaly detection algorithm to eliminate base stations with serious dynamic NLOS influence, completes anomaly elimination, and can also check whether the UWB base station module fails and completes the alarm; the method provided in this embodiment can increase the number of base stations indefinitely to increase the positioning range without increasing the positioning delay, improve the endurance of the positioning system, reduce the impact of the narrow channel NLOS environment to improve the positioning accuracy, use the robust positioning algorithm to increase the robustness of the positioning system, and check the base station failure in real time to facilitate the management of the positioning system.

Claims

1. A narrow channel switching positioning method based on UWB, characterized by: The following steps are involved: Step 1: Divide the area to be positioned into multiple positioning sub-areas, each positioning sub-area has one and only one positioning sub-area number, deploy several UWB base station modules in the area to be positioned, each UWB base station module has one and only one base station ID number, so that two adjacent positioning sub-areas share two UWB base station modules; the union of all positioning sub-areas is the area to be positioned, and the area of ​​the intersection of all positioning sub-areas is an empty set; correspond each positioning sub-area number with the base station ID number of the UWB base station module it contains to form a positioning system configuration table; store the positioning system configuration table and the three-dimensional coordinates of each UWB base station module in the host computer module; Step 2: Use the stationary UWB tag module to perform ranging polling on all UWB base station modules in the positioning area to obtain the real-time distance information of all UWB base station modules. The stationary UWB tag module packages all the obtained real-time distance information and the corresponding base station ID number and sends them to the host computer module; Step 3: The host computer module performs positioning and solving according to all the real-time distance information and the three-dimensional coordinates of the UWB base station module corresponding to the base station ID number, obtains the coordinate information of the stationary UWB tag module, and determines the positioning sub-area number of the positioning sub-area where the stationary UWB tag module is currently located. The host computer module packages the positioning system configuration table, the three-dimensional coordinates of each UWB base station module, and the positioning sub-area number of the positioning sub-area where the stationary UWB tag module is currently located and sends them to the UWB tag module; Step 4: When the UWB tag module moves in the positioning sub-area, the UWB tag module determines the base station ID number that needs to be polled for ranging according to the received positioning sub-area number by comparing the positioning system configuration table, and completes ranging with one UWB base station module at a time in sequence. After completing the ranging polling of all UWB base station modules in the positioning sub-area, the distance information of all UWB base station modules in the positioning sub-area is obtained; the distance information of the UWB base station module includes RSSI; Step 5: The UWB tag module obtains the RSSI of all UWB base station modules in the positioning sub-area, compares the RSSI with the threshold, removes the distance information with RSSI lower than the threshold, and performs positioning calculation on the remaining distance information in combination with the three-dimensional coordinates of the corresponding UWB base station module to obtain the real-time location information of the UWB tag module; Step 6: The UWB tag module performs filtering processing on the obtained real-time location information of the UWB tag module to obtain the real-time location of the tag; Step 7: The UWB tag module uploads the real-time distance and real-time location information of the tag of this ranging polling to the upper computer module; at the same time, the UWB tag module determines whether the current positioning sub-area of ​​the UWB tag module is switched with the positioning sub-area of ​​the previous round of ranging polling according to the real-time location of the tag. If a switch occurs, the positioning system configuration table is checked to determine which UWB base station modules the UWB tag module needs to poll with in the next ranging cycle, and step 4 is executed; if no switch occurs, the next UWB base station module is ranged in sequence; Step 8: The host computer module determines whether there is a missing UWB base station module by comparing the distance information of all UWB base station modules uploaded by the UWB tag module with the ID number. If so, a fault alarm is issued; the host computer module uses cluster analysis to determine whether there is an abnormal UWB base station module based on the distance information of all uploaded UWB base station modules; the host computer module only packages the base station ID number of the faulty missing UWB base station module and the base station ID number of the abnormal UWB base station module and sends them to the UWB tag module. The UWB tag module removes the base station ID number of the missing UWB base station module and the base station ID number of the abnormal UWB base station module in the next round of ranging.

2. The narrow channel switching positioning method based on UWB according to claim 1 is characterized in that: The positioning solution in step 3 and step 5 includes the following operations: When the number of UWB base station modules involved in positioning is ≥3, the positioning solution includes the following steps: Assume that the coordinate information of the UWB tag module is (x, y, z), and the three-dimensional coordinates of each UWB base station module are known to be (x i ,y i , z i ), the real-time distance information between the UWB tag module and each UWB base station module is d i , then the following system of equations can be constructed: Subtract the first n-1 equations from the last one and express them in matrix form to get AX=B: Define the error vector as: δ=AX-B When the error square sum is the smallest, X is the coordinate information of the desired UWB tag module; Construct the function f(x): f(x)=(AX-B) T (AX-B) Let the derivative of f(x) be 0, when A T When A is non-singular, we can solve: X=(A T A) -1 A T b Among them, A T A is the pseudo-inverse of the matrix being sought. + / Inverse Matrix A -1 ; Use the singular value decomposition method to find the pseudo-inverse A + / Inverse Matrix A -1 , get the coordinate information of the UWB tag module.

3. The narrow channel switching positioning method based on UWB according to claim 2 is characterized in that: When the number of UWB base station modules involved in positioning is 2, the positioning solution includes the following steps: The coordinate information of the two UWB base station modules is combined with the corresponding real-time distance, and two fuzzy coordinates are obtained according to the three-sided positioning algorithm: (x 11 ,y 11 ) and (x 22 ,y 22 ), according to the two fuzzy coordinate information, it is divided into the following two cases: Case 1: One of the fuzzy coordinates (x 11 ,y 11 ) is outside the area to be located, and another fuzzy coordinate (x 22 ,y 22 ) In the area to be located, select the fuzzy coordinates (x 22 ,y 22 ) as the real-time location information of the UWB tag module; Case 2: Assuming that the coordinate information of the UWB tag module at the last moment is (x0, y0), it is known that the two fuzzy coordinates are both in the area to be positioned. According to the coordinate information (x0, y0) of the UWB tag module at the last moment, calculate (x 11 ,y 11 )、(x 22 ,y 22 ) and (x0, y0), the fuzzy coordinates corresponding to the shorter distance between d1 and d2 are selected as the real-time location information of the UWB tag module.

4. The narrow channel switching positioning method based on UWB according to claim 1 is characterized in that: In step 4, the specific operations of completing ranging with one UWB base station module at a time in sequence include: Before the ranging begins, the UWB tag module broadcasts a Broadcast message, which contains the ID number of the base station with which communication needs to be established. Each UWB base station module receives and parses the Broadcast message, and only performs a TWR ranging communication when the base station ID number packaged in the Broadcast message is the same as its own base station ID number. The TWR ranging communication includes: using Poll message, Response message and Final message to complete a one-to-one ranging; including: The UWB base station module sends a Poll message to the UWB tag module. The UWB base station module records the Poll message sending timestamp T1 and immediately enters the waiting state after sending. round1 The UWB tag module waits for the Response message sent by the UWB tag module within the time; the UWB tag module waits for receiving the Poll message. If the message is received and the frame header is determined to be a Poll message, the UWB tag module records the Poll message receiving timestamp T2; The UWB tag module sends a Response message to the UWB base station module. After receiving the Poll message, the UWB tag module waits for T reply1 After T3, the UWB tag module records the timestamp of the Response message and immediately waits for the message to be received. round2 The UWB base station module waits for the Final message sent by the UWB base station module within T round1 The UWB base station module receives and identifies the correct Response message within T4. If the UWB base station module does not receive and identify the correct Response message within T round1 If a Response message is received within the time limit, it is considered as a timeout, the current ranging polling is terminated and the next ranging polling is started again; The UWB base station module sends a Final message to the UWB tag module. The Final message includes: RSSI, the timestamp recorded by the base station (T1, T4, T5) and the current UWB base station ID number. After receiving the Response message, the UWB base station module waits for T reply2 The UWB base station module records the Final message sending timestamp T5. If the UWB tag module is within T round2 The UWB base station module receives and identifies the correct Final message within T6. If the UWB tag module does not receive and identify the correct Final message within T7, the UWB base station module records the Final message reception timestamp T6. round2 If a Final message is received within the time limit, it is considered as a timeout, the current ranging polling is terminated and the next ranging polling is started again; The UWB tag module receives the Final message and combines the three timestamps T2, T3, and T6 of receiving the Poll message, sending the Response message, and receiving the Final message to calculate the distance information and complete the ranging; it is expressed as: T round1 =T4-T1 <h2 style=";text-align:left;direction:ltr">T<h2 style=";text-align:left;direction:ltr"> round2 <h2 style=";text-align:left;direction:ltr"> (T6-T3) <h2 style=";text-align:left;direction:ltr">T<h2 style=";text-align:left;direction:ltr"> reply1 <h2 style=";text-align:left;direction:ltr"> (T3-T2) T reply2 =T5-T4 Wherein, T1, T2, T3, T4, T5, and T6 timestamps represent the time when the UWB base station module Poll message is sent, the time when the UWB tag module Poll message is received, the time when the UWB tag module Response message is sent, the time when the UWB base station module Response message is received, the time when the UWB base station module Final message is sent, and the time when the UWB tag module Final message is received; T round1 Indicates the effective time period for the UWB base station module to wait for receiving the Response message after sending the Poll message. round2 Indicates the effective time period for the UWB tag module to wait for receiving the Final message after sending the Response message. reply1 Indicates the fixed time that the UWB tag module waits to send a Response message after receiving a Poll message, T reply2 Indicates the fixed time that the UWB base station module waits to send a Final message after receiving a Response message; The TOA is calculated using the following process: Get the flight time T prop Calculation formula: The flight time is multiplied by the speed of light constant c to obtain the distance value, completing the entire distance measurement process: Distance = T prop ×c.

5. The narrow channel switching positioning method based on UWB according to claim 1 is characterized in that: In step 6, the UWB tag module performs filtering processing on the obtained real-time location information of the UWB tag module to obtain the real-time location of the tag. The specific operations include: The UWB tag module uses the obtained real-time location information of the UWB tag module as the input of the Hample filter. By setting the window length and threshold multiple of the Hample filter, the outliers in the real-time location information of the UWB tag module are detected. Only when there are outliers, the median of the data in the window is used to replace the outliers, and the filtered location information is used as the real-time location of the tag.

6. A narrow channel switching positioning system based on UWB, characterized by: include: Several UWB base station modules are deployed inside the area to be located and used for ranging communication with the UWB tag modules; The UWB tag module is used for moving in the positioning sub-area. The UWB tag module determines the base station ID number that needs to be polled for ranging according to the received positioning sub-area number by comparing the positioning system configuration table, and completes ranging with one UWB base station module at a time in sequence. After completing the ranging polling of all UWB base station modules in the positioning sub-area, the distance information of all UWB base station modules in the positioning sub-area is obtained; the distance information of the UWB base station module includes RSSI; and the UWB tag module is used to obtain the RSSI of all UWB base station modules in the positioning sub-area, compare the RSSI with a threshold, eliminate the distance information with RSSI lower than the threshold, and combine the remaining distance information with the three corresponding UWB base station modules. dimensional coordinates to perform positioning and solving, and obtain the real-time position information of the UWB tag module; and the UWB tag module is used to filter the obtained real-time position information of the UWB tag module to obtain the real-time position of the tag; and the UWB tag module is used to upload the real-time distance of the current ranging polling and the real-time position information of the tag to the upper computer module; at the same time, the UWB tag module determines whether the current positioning sub-area of ​​the UWB tag module and the positioning sub-area of ​​the previous round of ranging polling are switched according to the real-time position of the tag. If switching occurs, the positioning system configuration table is checked to determine which UWB base station modules the UWB tag module needs to poll with in the next ranging cycle; if switching does not occur, the next UWB base station module is ranged in sequence; And the UWB tag module removes the base station ID number of the missing UWB base station module and the base station ID number of the abnormal UWB base station module in the next round of ranging; The host computer module is used to store the positioning system configuration table and the three-dimensional coordinates of each UWB base station module, wherein the positioning system configuration table is composed of the correspondence between each positioning sub-area number and the base station ID number of the UWB base station module contained therein; and is used to perform positioning and solving according to all the original distance information obtained and the three-dimensional coordinates of the UWB base station module corresponding to the base station ID number, obtain the coordinate information of the stationary UWB tag module, and determine the positioning sub-area number of the positioning sub-area where the stationary UWB tag module is currently located, and the host computer module packages the positioning system configuration table, the three-dimensional coordinates of each UWB base station module and the positioning sub-area number of the positioning sub-area where the stationary UWB tag module is currently located and sends them to the UWB tag module; and is used to determine whether there is a missing UWB base station module according to the real-time distance of the current ranging polling, and if so, a fault alarm is issued; the host computer module uses cluster analysis according to the real-time distance of the current ranging polling to determine whether there is an abnormal UWB base station module; the host computer module only packages the base station ID number of the missing UWB base station module and the base station ID number of the abnormal UWB base station module and sends them to the UWB tag module; Wherein, in the host computer module, all the original distance information and base station ID numbers are obtained by using a stationary UWB tag module to perform ranging polling on all UWB base station modules in the positioning area to obtain the original distance information of all UWB base station modules, and the stationary UWB tag module packages all the obtained original distance information and the corresponding base station ID numbers and sends them to the host computer module; Among them, the positioning sub-area is obtained by dividing the area to be positioned, each positioning sub-area has one and only one positioning sub-area number, and several UWB base station modules are deployed in the area to be positioned. Each UWB base station module has one and only one base station ID number, so that two adjacent positioning sub-areas share two UWB base station modules; the union of all positioning sub-areas is the area to be positioned, and the area of ​​the intersection of all positioning sub-areas is an empty set.

7. The narrow channel switching positioning system based on UWB according to claim 6 is characterized in that: In the UWB tag module, positioning and solving include: When the number of UWB base station modules involved in positioning is ≥3, the positioning solution includes the following steps: Assume that the coordinate information of the UWB tag module is (x, y, z), and the three-dimensional coordinates of each UWB base station module are known to be (x i ,y i ,z i ), the original distance information between the UWB tag module and each UWB base station module is d i , then the following system of equations can be constructed: Subtract the first n-1 equations from the last one and express them in matrix form to get AX=B: Define the error vector as: δ=AX-B When the error square sum is the smallest, X is the coordinate information of the desired UWB tag module; Construct the function f(x): f(x)=(AX-B) T (AX-B) Let the derivative of f(x) be 0, when A T When A is non-singular, we can solve: X=(A T A) -1 A T b Among them, A T A is the pseudo-inverse of the matrix being sought. + / Inverse Matrix A -1 ; Use the singular value decomposition method to find the pseudo-inverse A + / Inverse Matrix A -1 , get the coordinate information of the UWB tag module.

8. The narrow channel switching positioning system based on UWB according to claim 7 is characterized in that: In the UWB tag module, when the number of UWB base station modules participating in positioning is 2, the positioning solution includes the following steps: The coordinate information of the two UWB base station modules is combined with the corresponding real-time distance, and two fuzzy coordinates are obtained according to the three-sided positioning algorithm: (x 11 ,y 11 ) and (x 22 ,y 22 ), according to the two fuzzy coordinate information, it is divided into the following two cases: Case 1: One of the fuzzy coordinates (x 11 ,y 11 ) is outside the area to be located, and another fuzzy coordinate (x 22 ,y 22 ) In the area to be located, select the fuzzy coordinates (x 22 ,y 22 ) as the real-time location information of the UWB tag module; Case 2: Assuming that the coordinate information of the UWB tag module at the last moment is (x0, y0), it is known that the two fuzzy coordinates are both in the area to be positioned. According to the coordinate information (x0, y0) of the UWB tag module at the last moment, calculate (x 11 ,y 11 )、(x 22 ,y 22 ) and (x0, y0), the fuzzy coordinates corresponding to the shorter distance between d1 and d2 are selected as the real-time location information of the UWB tag module.

9. The narrow channel switching positioning system based on UWB according to claim 6, characterized in that: In the UWB tag module, the distance measurement is completed with one UWB base station module at a time in sequence, and the specific operations include: Before the ranging begins, the UWB tag module broadcasts a Broadcast message, which contains the ID number of the base station with which communication needs to be established. Each UWB base station module receives and parses the Broadcast message, and only performs a TWR ranging communication when the base station ID number packaged in the Broadcast message is the same as its own base station ID number. The TWR ranging communication includes: using Poll message, Response message and Final message to complete a one-to-one ranging; including: The UWB base station module sends a Poll message to the UWB tag module. The UWB base station module records the Poll message sending timestamp T1 and immediately enters the waiting state after sending. round1 The UWB tag module waits for the Response message sent by the UWB tag module within the time; the UWB tag module waits for receiving the Poll message. If the message is received and the frame header is determined to be a Poll message, the UWB tag module records the Poll message receiving timestamp T2; The UWB tag module sends a Response message to the UWB base station module. After receiving the Poll message, the UWB tag module waits for T reply1 After T3, the UWB tag module records the timestamp of the Response message and immediately waits for the message to be received. round2 The UWB base station module waits for the Final message sent by the UWB base station module within T round1 The UWB base station module receives and identifies the correct Response message within T4. If the UWB base station module does not receive and identify the correct Response message within T round1 If a Response message is received within the time limit, it is considered as a timeout, the current ranging polling is terminated and the next ranging polling is started again; The UWB base station module sends a Final message to the UWB tag module. The Final message includes: RSSI, the timestamp recorded by the base station (T1, T4, T5) and the current UWB base station ID number. After receiving the Response message, the UWB base station module waits for T reply2 The UWB base station module records the Final message sending timestamp T5. If the UWB tag module is within T round2 The UWB base station module receives and identifies the correct Final message within T6. If the UWB tag module does not receive and identify the correct Final message within T7, the UWB base station module records the Final message reception timestamp T6. round2 If a Final message is received within the time limit, it is considered as a timeout, the current ranging polling is terminated and the next ranging polling is started again; The UWB tag module receives the Final message and combines the three timestamps T2, T3, and T6 of receiving the Poll message, sending the Response message, and receiving the Final message to calculate the distance information and complete the ranging; it is expressed as: T round1 =T4-T1 <h2 style=";text-align:left;direction:ltr">T<h2 style=";text-align:left;direction:ltr"> round2 <h2 style=";text-align:left;direction:ltr"> (T6-T3) <h2 style=";text-align:left;direction:ltr">T<h2 style=";text-align:left;direction:ltr"> reply1 <h2 style=";text-align:left;direction:ltr"> (T3-T2) T reply2 =T5-T4 Wherein, T1, T2, T3, T4, T5, and T6 timestamps represent the time when the UWB base station module Poll message is sent, the time when the UWB tag module Poll message is received, the time when the UWB tag module Response message is sent, the time when the UWB base station module Response message is received, the time when the UWB base station module Final message is sent, and the time when the UWB tag module Final message is received; T round1 Indicates the effective time period for the UWB base station module to wait for receiving the Response message after sending the Poll message. round2 Indicates the effective time period for the UWB tag module to wait for receiving the Final message after sending the Response message. reply1 Indicates the fixed time that the UWB tag module waits to send a Response message after receiving a Poll message, T reply2 Indicates the fixed time that the UWB base station module waits to send a Final message after receiving a Response message; The TOA is calculated using the following process: Get the flight time T prop Calculation formula: The flight time is multiplied by the speed of light constant c to obtain the distance value, completing the entire distance measurement process: Distance = T prop ×c.

10. The narrow channel switching positioning system based on UWB according to claim 6, characterized in that: The UWB tag module is used to filter the obtained real-time location information of the UWB tag module to obtain the real-time location of the tag. The specific operations include: The UWB tag module uses the obtained real-time location information of the UWB tag module as the input of the Hample filter. By setting the window length and threshold multiple of the Hample filter, the outliers in the real-time location information of the UWB tag module are detected. Only when there are outliers, the median of the data in the window is used to replace the outliers, and the filtered location information is used as the real-time location of the tag.

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