Analysis and improvement method, system and storage medium for UWB ranging error

Abstract

The present invention provides a method, system and storage medium for analyzing and improving UWB ranging errors. In the method, a first ranging device and a second ranging device perform n rounds of ranging signal interaction, each round of ranging signal interaction starts with the first ranging device sending a message to the second ranging device, and ends with the first ranging device receiving a message replied by the second ranging device, and the time points of the first ranging device and the second ranging device sending and receiving messages are recorded respectively, and then the clock drift rate ratio is calculated based on the recorded time points, and the result of each round of ranging in the n rounds of signal interaction is calculated in sequence based on the clock drift rate ratio, and the final ranging result is calculated based on the result of the n rounds of ranging. Compared with the traditional bilateral dual-range algorithm, the present invention can effectively reduce the error generated in the ranging process, thereby improving the accuracy of positioning.

Description

Technical Field

[0001] The present invention relates to the field of UWB ranging technology, and in particular to a method, system and storage medium for analyzing and improving UWB ranging errors. Background Art

[0002] In the ranging and positioning algorithms based on Ultra Wide Band (UWB), they are mainly divided into Time Difference of Arrival (TDOA) and Time of Arrival (TOA). The TDOA positioning method requires all positioning base stations to maintain strict time synchronization, which is difficult to implement in engineering. Therefore, the positioning method based on UWB usually adopts the TOA ranging algorithm. One-way ranging, two-way ranging, unilateral two-way ranging, and bilateral two-way ranging are the most commonly used ranging protocols for TOA estimation. Among them, the most widely used in the industry is the Double-sided Two-way Ranging algorithm. The basic principle of this algorithm is that the positioning tag and multiple base stations perform ranging operations (such as Figure 1 As shown in the figure), then through triangulation positioning, assuming that the positioning tag point and the base station coordinate point can form a triangle, the angle formed by the base station and the positioning tag point can be measured by calculating the length of the triangle side, and the real-time coordinates of the positioning tag can be calculated, such as Figure 2 As shown in the figure. Its essence is to calculate the distance by measuring the flight time (TOF) of the signal between the transmitting and receiving nodes multiplied by the speed of light. At the same time, the two parties of the ranging eliminate the ranging error caused by the different clock errors of both parties through the interaction of two signals. However, in the actual application process, after eliminating the ranging error caused by the clock error of the ranging device, the ranging effect is still not very ideal. In an environment without obstacles, the positioning accuracy range is about 40cm.

[0003] After a lot of tests, the main sources of errors in the UWB ranging process are as follows: 1) Clock drift: During the ranging process, different timestamps need to be recorded by sending signals. In actual situations, due to objective factors (such as equipment material process, and ambient temperature, etc.), the clock frequencies of the transceiver devices may be slightly different, that is, the clock drift phenomenon, which will cause the receiving device to obtain inaccurate time information of the signal. 2) Error in reading the signal transmission and reception time: When the device reads the signal transmission and reception timestamp, there will be an error in the form of white noise distribution, and its value is about (3E-10) seconds. If the time for a device to send a signal is t seconds, the actual signal transmission time read by the device may be any value between: t-(3E-10) seconds and t+(3E-10) seconds. The device needs at least one information exchange for one ranging, that is, reading and writing twice. Therefore, in the worst case, the error value is (3E-10)*4*C=0.36 meters. Since existing time drift correction algorithms are based on the device successfully reading the correct sending and receiving time, the time error generated by reading the signal will cause deviations in the clock drift correction process.

[0004] From the above analysis, it can be seen that the original bilateral two-way ranging algorithm can only reduce the error caused by clock drift, but the error caused by the error in the reading signal reception and transmission time, as well as the correction error of the time offset caused at the same time, cannot be eliminated. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a method for analyzing and improving UWB ranging errors, which can effectively reduce the errors generated in the ranging process and thus improve the positioning accuracy.

[0006] To achieve the above-mentioned object of the invention, the first aspect of the present invention provides a method for analyzing and improving UWB ranging errors, comprising the following steps:

[0007] S101, a first ranging device performs n rounds of ranging signal interaction with a second ranging device, where each round of ranging signal interaction starts with the first ranging device sending a message to the second ranging device and ends with the first ranging device receiving a reply message from the second ranging device;

[0008] S102, respectively recording the time points at which the first ranging device and the second ranging device send and receive messages;

[0009] S103, calculating the clock drift rate ratio based on the recorded time points;

[0010] S104, sequentially calculating the result of each round of ranging in n rounds of signal interaction based on the clock drift rate ratio;

[0011] S105. Calculate a final ranging result based on the results of n rounds of ranging.

[0012] Furthermore, in each round of signal interaction, the message replied by the second ranging device and received by the first ranging device and the message sent by the first ranging device and received by the second ranging device are both filtered by the filter.

[0013] Further, the time point at which the first ranging device sends a message each time is recorded as τAs1, τAs2, ..., τAsn, and the time point at which the message is received each time is recorded as τAr1, τAr2, ..., τArn; the time point at which the second ranging device sends a message each time is recorded as τBs1, τBs2, ..., τBsn, and the time point at which the message is received each time is recorded as τBr1, τBr2, ..., τBrn, and the clock drift rate ratio is calculated based on the recorded time points, and the calculation formula thereof is shown in formula (1),

[0014] W=(τAsn-τAs1) / (τBrn-τBr1) (1)

[0015] Where W is the clock drift rate ratio, and n is the number of signal interaction rounds.

[0016] Further, the step of sequentially calculating the result of each round of ranging in n rounds of signal interaction based on the clock drift rate ratio specifically includes:

[0017] Calculate the time t from when the first ranging device sends a message to when the second ranging device receives the message roundAn ;

[0018] Calculate the time t from when the second ranging device receives the message sent by the first ranging device to when the second ranging device replies to the message replyBn ;

[0019] According to t roundAn ,t replyBn The signal flight duration of the corresponding round is calculated by the ratio of the clock drift rate, where n represents the signal interaction round;

[0020] The ranging results of the corresponding rounds are calculated based on the signal flight duration and signal transmission speed.

[0021] Furthermore, the calculation of the final ranging result based on the results of n rounds of ranging specifically includes the following steps:

[0022] Determine whether the number of signal interaction rounds n is an odd number. If n is an odd number, the final ranging result L is calculated by formula (2):

[0023] L=L (n+1) / 2 (2);

[0024] If n is an even number, the final ranging result is calculated by formula (3):

[0025]

[0026] A second aspect of the present invention provides a UWB ranging error analysis and improvement system, the system comprising: a first ranging device, a second ranging device, a recording module, a first calculation module, a second calculation module and a third calculation module, wherein:

[0027] The first ranging device is used to perform n rounds of signal interaction with the second ranging device, each round of signal interaction starts with the first ranging device sending a message to the second ranging device and ends with the first ranging device receiving a reply message from the second ranging device;

[0028] The recording module is used to record the time points when the first ranging device and the second ranging device send and receive messages respectively;

[0029] The first calculation module is used to calculate the clock drift rate ratio based on the time point recorded by the recording module;

[0030] The second calculation module is used to sequentially calculate the result of each round of ranging in n rounds of signal interaction based on the clock drift rate ratio;

[0031] The third calculation module is used to calculate the final ranging result based on the results of n rounds of ranging.

[0032] A third aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the method described in the first aspect is implemented.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention reduces the time drift error caused by the system by performing multiple rounds of ranging signal interactions between ranging devices;

[0035] 2. By calculating the clock drift rate ratio, the results of multiple rounds of ranging are further calculated based on the clock drift rate ratio, and the final ranging result is calculated according to the results of multiple rounds of ranging, so as to eliminate the error caused by the device reading the receiving and transmitting signals, so that the positioning accuracy of the method provided by the present invention is far better than the traditional bilateral dual-range ranging algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only preferred embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1It is a schematic diagram of the positioning tag and multiple base station ranging networking in the prior art.

[0038] Figure 2 It is a schematic diagram of the TOA positioning principle in the prior art.

[0039] Figure 3 The present invention provides a schematic diagram of the overall process of analyzing and improving a method for UWB ranging error.

[0040] Figure 4 The figure is a schematic diagram of the principle of a method for improving UWB ranging error provided by an embodiment of the present invention.

[0041] Figure 5 The present invention is a schematic diagram of the overall structure of a UWB ranging error analysis and improvement system provided by an embodiment of the present invention.

[0042] Figure 6 It is a schematic diagram of the ranging result of the one-way ranging algorithm in the prior art.

[0043] Figure 7 It is a schematic diagram of the ranging result of the two-way ranging algorithm in the prior art.

[0044] Figure 8 It is a schematic diagram of the results of ten interactive distance measurements of the improved method provided in an embodiment of the present invention.

[0045] Fig. 9 It is a schematic diagram of the interactive ranging results of 100 times of the improved method provided in an embodiment of the present invention.

[0046] In the figure, 1 is a first distance measuring device, 2 is a second distance measuring device, 3 is a recording module, 4 is a first calculation module, 5 is a second calculation module, and 6 is a third calculation module. DETAILED DESCRIPTION

[0047] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The enumerated embodiments are only used to explain the present invention and are not used to limit the scope of the present invention.

[0048] Reference Figure 3 and Figure 4 This embodiment provides a method for analyzing and improving UWB ranging errors, the method comprising the following steps:

[0049] S101: A first ranging device and a second ranging device perform n rounds of ranging signal interaction. Each round of ranging signal interaction starts with the first ranging device sending a message to the second ranging device and ends with the first ranging device receiving a reply message from the second ranging device.

[0050] For example, the first ranging device first sends a message to the second ranging device, and the second ranging device immediately replies to the first ranging device after receiving the message, and this cycle repeats for n rounds. The messages received by the first ranging device and the second ranging device are filtered through a filter to filter out excessive noise interference.

[0051] S102: Record the time points at which the first ranging device and the second ranging device send and receive messages respectively.

[0052] S103: Calculate the clock drift rate ratio based on the recorded time points.

[0053] S104. Calculate the result of each round of ranging in n rounds of signal interaction in sequence based on the clock drift rate ratio.

[0054] S105. Calculate a final ranging result based on the results of n rounds of ranging.

[0055] Specifically, in step S102, the time point at which the first ranging device sends a message each time is recorded in sequence as τAs1, τAs2, ..., τAsn, and the time point at which the first ranging device receives a message each time is recorded in sequence as τAr1, τAr2, ..., τArn. The time point at which the second ranging device sends a message each time is recorded in sequence as τBs1, τBs2, ..., τBsn, and the time point at which the second ranging device receives a message each time is recorded in sequence as τBr1, τBr2, ..., τBrn. In step S103, the clock drift rate ratio is calculated based on the recorded time points, and the calculation formula thereof is shown in formula (1),

[0056] W=(τAsn-τAs1) / (τBrn-τBr1) (1)

[0057] Where W is the clock drift rate ratio, and n is the number of signal interaction rounds.

[0058] In step S104, the result of each round of ranging in the n rounds of ranging signal interaction is calculated in sequence based on the clock drift rate ratio, which specifically includes the following steps:

[0059] Calculate the time t from when the first ranging device sends a message to when the second ranging device receives the message roundAn , as shown below:

[0060] t roundAn =τ Arn -τ Asn

[0061] Where n represents the round, τ Arn is the time point when the first ranging device in this round receives the message, τ Asn The time point when the first ranging device sends a message in this round.

[0062] Calculate the time t from when the second ranging device receives the message sent by the first ranging device to when the second ranging device replies to the message replyBn , as shown below:

[0063] t replyBn =τ Bsn -τ Brn

[0064] Where n represents the round, τ Brn is the time point when the second ranging device receives the message in this round, τ Bsn The time point when the second ranging device sends a message in this round.

[0065] According to t roundAn ,t replyBn The signal flight duration of the corresponding round is calculated based on the clock drift rate ratio. The signal flight duration T tof The expression is as follows:

[0066] T tof =(t roundAn –t replyBn *W) / 2

[0067] The ranging result of the corresponding round is calculated according to the signal flight duration and signal transmission speed. The ranging result L of the nth round is n The expression is as follows:

[0068] L n =T tof *C

[0069] Wherein C represents the signal transmission speed, and in this embodiment, C takes the value of the speed of light.

[0070] In step S105, the calculation of the final ranging result based on the results of n rounds of ranging specifically includes the following steps:

[0071] Determine whether the number of signal interaction rounds n is an odd number. If n is an odd number, the final ranging result L is calculated by formula (2):

[0072] L=L (n+1) / 2 (2)

[0073] That is, when the number of ranging signal interaction rounds is an odd number, the median of multiple rounds of ranging results is taken as the final ranging result.

[0074] If n is an even number, the final ranging result is calculated by formula (3):

[0075]

[0076] As an optional implementation, during the process of executing the method described in the above embodiment, it is also detected whether the moving speed of the positioning tag itself exceeds a preset threshold. If it exceeds the preset threshold, a prompt message is issued and the execution method is terminated, because if the positioning tag itself is in a high-speed moving state, the ranging process will become meaningless.

[0077] In a specific embodiment of the present invention, the method is tested in an actual environment, wherein the test results are shown in Table 1. When the number of ranging signal interactions is 10, each ranging takes 25 milliseconds, and the positioning accuracy is within 0.05 meters, which is suitable for using the method to locate the robot when it is moving. When the number of ranging signal interactions is 100, each ranging takes 250 milliseconds, and the positioning accuracy is within 0.03 meters, which is suitable for using the method to locate the robot when it is stationary.

[0078] Table 1 Algorithm test results provided in this embodiment

[0079] Number of signal interactions n Each distance measurement takes time Accuracy Suitable scenes 10 25ms 0.05m Used when the robot is moving 100 250ms 0.03m Use when the robot is stationary

[0080] Reference Figure 6 to Figure 9 , Figure 6 One-way ranging algorithm and Figure 7 The ranging results of the two-way ranging algorithm in the above examples all have large fluctuations and large errors. Figure 8 and Fig. 9 It can be seen that the ranging result of the method provided in this embodiment is more stable and has a smaller error than the aforementioned two algorithms. At the same time, the result of one hundred interactions is more stable than the ranging result of ten interactions. It can also be seen from Table 2 that the mean square errors of the improved algorithm provided in this embodiment for ten interactions and one hundred interactions are 0.00857 and 0.0044878 respectively, which are much smaller than the mean square errors of the ranging results of the one-way ranging algorithm and the two-way ranging algorithm, indicating that its ranging result fluctuates less and has a relatively small error.

[0081] Table 2 Measurement distance results

[0082]

[0083] The method provided in this embodiment successfully eliminates most of the ranging errors caused by different clock errors between the two parties through multiple signal interactions between the two ranging parties. The positioning accuracy is improved from 0.4 meters to within 0.03 meters, which is a significant improvement compared to the traditional bilateral dual-range algorithm.

[0084] Based on the same inventive concept as the aforementioned method embodiment, another embodiment of the present invention provides a UWB ranging error analysis and improvement system, referring to Figure 5The system comprises a first distance measuring device 1, a second distance measuring device 2, a recording module 3, a first calculation module 4, a second calculation module 5 and a third calculation module 6, wherein:

[0085] The first ranging device 1 is used to perform n rounds of signal interaction with the second ranging device 2. Each round of signal interaction starts with the first ranging device 1 sending a message to the second ranging device 2 and ends with the first ranging device 1 receiving a reply message from the second ranging device 2.

[0086] The recording module 3 is used to record the time points when the first distance measuring device 1 and the second distance measuring device 2 send and receive messages respectively.

[0087] The first calculation module 4 is used to calculate the clock drift rate ratio based on the time point recorded by the recording module.

[0088] The second calculation module 5 is used to calculate the result of each round of ranging in n rounds of signal interaction in sequence based on the clock drift rate ratio.

[0089] The third calculation module 6 is used to calculate the final distance measurement result based on the results of n rounds of distance measurement.

[0090] The system is used to implement the method described in the aforementioned method embodiment. Its working principle and technical effects can all be referred to in the aforementioned method embodiment and will not be described in detail here.

[0091] Another embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the method described in the foregoing method embodiment when executed by a processor.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for analyzing and improving UWB ranging errors, characterized in that: The method comprises the following steps: S101, a first ranging device performs n rounds of ranging signal interaction with a second ranging device, where each round of ranging signal interaction starts with the first ranging device sending a message to the second ranging device and ends with the first ranging device receiving a reply message from the second ranging device; S102, respectively recording the time points at which the first ranging device and the second ranging device send and receive messages; S103, calculating the clock drift rate ratio based on the recorded time points; S104, sequentially calculating the result of each round of ranging in n rounds of signal interaction based on the clock drift rate ratio; S105, calculating the final distance measurement result based on the results of n rounds of distance measurement; The calculation of the final ranging result based on the results of n rounds of ranging specifically includes the following steps: Determine whether the number of signal interaction rounds n is an odd number. If n is an odd number, the final ranging result L is calculated by formula (2): L=L (n+1) / 2 (2); If n is an even number, the final distance measurement result L is calculated by formula (3):

2. The method for analyzing and improving UWB ranging error according to claim 1, characterized in that: In each round of signal interaction, the message replied by the second ranging device and received by the first ranging device and the message sent by the first ranging device and received by the second ranging device are both filtered by the filter.

3. The method for analyzing and improving UWB ranging error according to claim 1, characterized in that: The time point at which the first ranging device sends a message each time is recorded as τAs1, τAs2, ..., τAsn, and the time point at which the message is received each time is recorded as τAr1, τAr2, ..., τArn; the time point at which the second ranging device sends a message each time is recorded as τBs1, τBs2, ..., τBsn, and the time point at which the message is received each time is recorded as τBr1, τBr2, ..., τBrn. The clock drift rate ratio is calculated based on the recorded time points, and the calculation formula is shown in formula (1). W = (τAsn-τAs1) / (τBrn - τBr1) (1) Where W is the clock drift rate ratio, and n is the number of signal interaction rounds.

4. The method for analyzing and improving UWB ranging error according to claim 3, characterized in that: The step of sequentially calculating the result of each round of ranging in n rounds of signal interaction based on the clock drift rate ratio specifically includes: Calculate the time t from when the first ranging device sends a message to when the second ranging device receives the message roundAn ; Calculate the time t from when the second ranging device receives the message sent by the first ranging device to when the second ranging device replies to the message replyBn ; According to t roundAn ,t replyBn The signal flight duration of the corresponding round is calculated by the ratio of the clock drift rate, where n represents the signal interaction round; The ranging results of the corresponding rounds are calculated based on the signal flight duration and signal transmission speed.

5. A UWB ranging error analysis and improvement system, characterized in that: The system includes a first distance measuring device, a second distance measuring device, a recording module, a first calculation module, a second calculation module and a third calculation module, wherein: The first ranging device is used to perform n rounds of signal interaction with the second ranging device, each round of signal interaction starts with the first ranging device sending a message to the second ranging device and ends with the first ranging device receiving a reply message from the second ranging device; The recording module is used to record the time points when the first ranging device and the second ranging device send and receive messages respectively; The first calculation module is used to calculate the clock drift rate ratio based on the time point recorded by the recording module; The second calculation module is used to sequentially calculate the result of each round of ranging in n rounds of signal interaction based on the clock drift rate ratio; The third calculation module is used to calculate the final distance measurement result based on the results of n rounds of distance measurement; The calculation of the final ranging result based on the results of n rounds of ranging specifically includes the following steps: Determine whether the number of signal interaction rounds n is an odd number. If n is an odd number, the final ranging result L is calculated by formula (2): L=L (n+1) / 2 (2); If n is an even number, the final distance measurement result L is calculated by formula (3):

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 4 is implemented.

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