A UWB high-precision positioning method and system

Abstract

The application discloses a UWB high-precision positioning method and system, comprising the following steps: obtaining the one-way radio electromagnetic wave transmission time difference obtained by communication between each base station and a tag in a current single ranging stage, the coordinate information of each base station and the antenna delay compensation curve obtained by pre-solution communication between each base station and the tag; calculating the distance between each base station and the tag according to the obtained data; and determining the real-time position coordinates of the tag according to the calculated distance between each base station and the tag. Advantages: the ranging source data precision between the base station and the tag is improved, and finally the UWB positioning precision is improved.

Description

Technical Field

[0001] This invention relates to a UWB high-precision positioning method and system, belonging to the field of UWB wireless positioning technology. Background Technology

[0002] Currently, indoor positioning technologies include GPS, BeiDou, Bluetooth, Wi-Fi, ZigBee, and UWB (Ultra-Wideband) wireless network technologies. Among these, UWB positioning boasts high accuracy, reaching centimeter-level precision, making it suitable for high-precision positioning scenarios. The mainstream UWB positioning algorithms are based on TOA (Time of Arrival) or TDOA (Time Difference of Arrival). The TDOA algorithm requires only one communication between the base station and tag per ranging round, offering the advantage of supporting a large tag capacity. However, it suffers from high requirements for time synchronization accuracy between base stations. In practice, system errors such as varying line lengths and limited clock synchronization accuracy make perfect base station synchronization difficult to achieve. Furthermore, the calculated data relies on the time difference of arrival, and small errors are easily amplified, leading to decreased accuracy. Overall, the technology has a high barrier to entry, resulting in relatively limited applications. In contrast, the TOA algorithm requires the tag to sequentially measure distances with multiple base stations for each positioning cycle. While the tag capacity is lower, its algorithm principle is simpler, utilizing message exchange between the base station and tag, eliminating the need for time synchronization between base stations. This makes it more widely used in practical engineering. In addition, all algorithms have systematic errors, including antenna delay, such as antenna delay error in ranging between UWB devices and non-line-of-sight error introduced by the packaging shell (collectively referred to as "antenna delay error"), which result in low accuracy of the final positioning coordinate solution. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a UWB high-precision positioning method and system, which improves positioning accuracy by improving the accuracy of UWB positioning source data.

[0004] To solve the above-mentioned technical problems, the present invention provides a UWB high-precision positioning method, comprising:

[0005] The system obtains the one-way radio electromagnetic wave transmission time difference, coordinate information of each base station, and antenna delay compensation curves for communication between each base station and the tag during the current single ranging phase.

[0006] The distance between each base station and the tag is calculated based on the obtained one-way radio electromagnetic wave transmission time difference and antenna delay compensation curve;

[0007] The real-time location coordinates of the tag are determined based on the calculated distance between each base station and the tag, and the coordinate information of each base station.

[0008] Furthermore, the process of obtaining the one-way radio electromagnetic wave transmission time difference obtained by the current single ranging phase of each base station and the tag communication includes:

[0009] The TOA algorithm is used to perform a single ranging between the tag and the base station. The single ranging between the tag and the base station is achieved through several interactive messages between the tag and the base station, and the length of each interactive message remains unchanged.

[0010] For each interaction message, the base station or tag records the corresponding timestamp;

[0011] Calculate the one-way radio electromagnetic wave transmission time difference based on the time stamps of all records.

[0012] Furthermore, when the tag sends a message to the base station, the tag will transmit the recorded timestamp delayed by 1 frame to the base station.

[0013] Furthermore, the process of solving the antenna delay compensation curve for communication between each base station and the tag includes:

[0014] Static line-of-sight tests were conducted between each base station and tag at different typical distance values ​​to obtain multiple sets of wireless transmission time difference and line-of-sight distance value pairs under different line-of-sight distances. Antenna delay error compensation curves for each base station and tag were then fitted.

[0015] Furthermore, the process of determining the real-time location coordinates of the tag based on the calculated distance between each base station and the tag includes:

[0016] The delay error of each base station is determined based on the antenna delay error compensation curve of each base station and the one-way radio electromagnetic wave transmission time difference dltT.

[0017] The distance between each base station and the tag is obtained by subtracting the delay error corresponding to the base station from the one-way radio electromagnetic wave transmission time difference dltT of each base station, multiplying it by the time resolution tick, and then multiplying it by the electromagnetic wave transmission speed.

[0018] The real-time location coordinates of the tags are solved using the least squares method based on the distance between each base station and the tag, as well as the coordinate information of each base station.

[0019] A UWB high-precision positioning system includes: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include instructions for performing any of the methods described.

[0020] The beneficial effects achieved by this invention are as follows:

[0021] By utilizing precise time stamps transmitted with a one-frame delay for each round of messages and fitting different curves to compensate for antenna delay errors based on the differences between different base stations, the system error is reduced by combining the two methods. This improves the source ranging accuracy between the base station and the tag, and ultimately improves the tag positioning coordinates obtained by the least squares method. Attached Figure Description

[0022] Figure 1 A flowchart of a method for improving UWB positioning accuracy provided by the present invention;

[0023] Figure 2 The diagram illustrates the three-time message exchange and time stamping process using the TWR interaction method in the TOA algorithm provided by this invention. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0025] Implementation Case:

[0026] Suppose there is a positioning test system consisting of 1 tag and 3 base stations, and the real-time location of the tag needs to be determined.

[0027] First, design a unified length communication frame format. For example, the following table shows a communication frame length format consisting of 20 bytes. The frame category can be simply 1, 2, 3, 4 to distinguish the sequential interaction messages between the base station and the tag in each round of ranging.

[0028]

[0029] Secondly, for a single ranging operation between a tag and a base station, a three-way message exchange (TWR) method can be used, such as... Figure 2 The three communication interactions are as follows: the tag initiates ranging frame 1 (Round 1) to the base station; the base station immediately replies with frame 2 (Round 2) after receiving frame 1 from the tag; and the tag immediately sends frame 3 (Round 3) after receiving frame 2 from the base station. The timestamp fields 1, 2, and 3 of frames Round 2 and Round 3 are always filled with 0. The timestamps read from the UWB chip during the interaction process are:

[0030] In the first interaction, the tag sends Round 1. After receiving Round 1, the base station records the reception time stamp t. R1_rx ;

[0031] In the second interaction, the base station replies with Round 2. After receiving Round 2, the tag records the time stamp t.R1_tx and t R2_rx ;

[0032] In the third interaction, the tag sends Round 3. After receiving Round 3, the base station records the time stamp t. R2_tx and t R3_rx Simultaneously, the tag detects successful transmission and records the time stamp t of Round 3. R3_tx .

[0033] The above three interactions constitute the first round of two-point ranging between the tag and the base station.

[0034] In the fourth interaction, the tag initiates the second round of ranging, Round 1, and fills the time stamp 1, time stamp 2, and time stamp 3 fields of the second round Round 1 frame with the t recorded by the tag in the previous round. R1_tx t R2_rx t R3_tx After the base station receives the second Round 1 message, the base station records the second round ranging time stamp t. R1_rx Simultaneously, it parses the three timestamps sent by the tag in Round 1, and combines them with the t recorded by the base station itself. R1_rx t R2_tx t R3_rx The time difference dltT between the base station and the tag is calculated using the following formula based on the six time scales.

[0035] dltT1=t R2_rx -t R1_tx

[0036] dltT2=t R2_tx -t R1_rx

[0037] dltT3=t R3_rx -t R2_tx

[0038] dltT4=t R3_tx -t R2_rx

[0039] dltT=(dltT1*dltT3–dltT2*dltT4) / (dltT1+dltT2+dltT3+dltT4)

[0040] The fifth and sixth interactions thereafter repeat the logic of the second and third interactions, with each round of ranging repeating every three interactions. The ranging interactions between other base stations and tags are similar.

[0041] Secondly, before the system is fully set up for formal positioning, using one base station and a tag, static line-of-sight tests are conducted at different typical distance values ​​(e.g., 1 meter, 2 meters, 3 meters…, 20 meters). Each distance point is tested 1000 times, yielding 1000 dltT values ​​at each distance. The average value is taken to obtain 20 pairs of (dltT, distance) values. The distance is converted into the corresponding number of transmission ticks, denoted as dltTs. dltT-dltTs represents the delay error. A scatter plot is plotted (horizontal axis: dltT, vertical axis: dltT-dltTs). The shape of the scatter plot is observed, and either a logarithmic curve, a polynomial curve, or a least-squares straight line is used, or a combination of these curves is used to fit the antenna delay compensation curve. Furthermore, considering the individual differences between different base stations, a similar antenna delay compensation curve can be calculated for each base station and tag for greater accuracy.

[0042] Finally, the relevant parameters of the obtained antenna delay compensation curve and the base station coordinates are pre-configured into the host computer program. During positioning, each base station sends the current dltT obtained from communicating with the tag to the host computer via the network. The host computer, based on the received dltT and base station number, subtracts the delay error by multiplying by the unit tick time resolution, and then multiplies by the electromagnetic wave transmission speed, i.e., the speed of light, to obtain the precise distance between each base station and the tag. The formula is as follows. Finally, the least squares method is used to solve for the real-time position coordinates of the tag.

[0043] S=(dltT–f(dltT))*T tick *c

[0044] In the formula, S represents the distance between the base station and the tag, f(x) represents the error fitting curve function between the base station and the tag, and T tick This represents the time resolution corresponding to a single tick, and c represents the speed of electromagnetic wave propagation, i.e., the speed of light.

[0045] Accordingly, the present invention also provides a UWB high-precision positioning system, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include instructions for performing any of the methods described herein.

[0046] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0047] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0048] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0049] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0050] 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 technical principles 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 UWB high-precision positioning method, characterized in that, include: The system obtains the one-way radio electromagnetic wave transmission time difference, coordinate information of each base station, and antenna delay compensation curves for communication between each base station and the tag during the current single ranging phase. The distance between each base station and the tag is calculated based on the obtained one-way radio electromagnetic wave transmission time difference and antenna delay compensation curve; The real-time location coordinates of the tag are determined based on the calculated distance between each base station and the tag, and the coordinate information of each base station. The process of solving the antenna delay compensation curve for communication between each base station and the tag includes: Static line-of-sight tests were conducted between each base station and tag at different typical distance values ​​to obtain multiple sets of wireless transmission time difference and line-of-sight distance value pairs under different line-of-sight distances. Antenna delay error compensation curves for each base station and tag were then fitted.

2. The UWB high-precision positioning method according to claim 1, characterized in that, The process of obtaining the one-way radio electromagnetic wave transmission time difference obtained by each base station in the current single ranging phase and tag communication includes: The TOA algorithm is used to perform a single ranging between the tag and the base station. The single ranging between the tag and the base station is achieved through several interactive messages between the tag and the base station, and the length of each interactive message remains unchanged. For each interaction message, the base station or tag records the corresponding timestamp; Calculate the one-way radio electromagnetic wave transmission time difference based on the time stamps of all records.

3. The UWB high-precision positioning method according to claim 2, characterized in that, When the tag sends a message to the base station, the tag will transmit the recorded timestamp delayed by 1 frame to the base station.

4. The UWB high-precision positioning method according to claim 1, characterized in that, The process of determining the real-time location coordinates of the tag based on the calculated distance between each base station and the tag includes: Based on the antenna delay error compensation curves of each base station and the one-way radio electromagnetic wave transmission time difference dltT Determine the delay error corresponding to each base station; Utilizing the time difference in one-way radio electromagnetic wave transmission between each base station dltT After deducting the delay error corresponding to the base station, multiply by the time resolution. tick Then multiply by the electromagnetic wave transmission speed to get the distance between each base station and the tag; The real-time location coordinates of the tags are solved using the least squares method based on the distance between each base station and the tag, as well as the coordinate information of each base station.

5. A UWB high-precision positioning system, characterized in that, include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for performing any of the methods according to claims 1 to 4.

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