CN114063049A - Method, system and storage medium for UWB ranging error analysis and improvement - Google Patents

Method, system and storage medium for UWB ranging error analysis and improvement Download PDF

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CN114063049A
CN114063049A CN202111280398.5A CN202111280398A CN114063049A CN 114063049 A CN114063049 A CN 114063049A CN 202111280398 A CN202111280398 A CN 202111280398A CN 114063049 A CN114063049 A CN 114063049A
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ranging
message
calculating
ranging device
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严海波
孙豪
于建刚
于一凡
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    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
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Abstract

The invention provides a method, a system and a storage medium for analyzing and improving UWB ranging errors, wherein in the method, a first ranging device and a second ranging device carry out n-wheel ranging signal interaction, the beginning of the ranging signal interaction of each wheel is started by the first ranging device sending a message to the second ranging device, the end of the ranging signal interaction of each wheel is ended by the first ranging device receiving a message replied by the second ranging device, time points of the first ranging device and the second ranging device sending the message and receiving the message are respectively recorded, then a clock drift rate ratio is calculated based on the recorded time points, the ranging result of each wheel in the n-wheel signal interaction is sequentially calculated based on the clock drift rate ratio, and the final ranging result is calculated based on the ranging result of n-wheel. Compared with the traditional bilateral double-distance algorithm, the method can effectively reduce the error generated in the distance measurement process, and further improve the positioning precision.

Description

Method, system and storage medium for UWB ranging error analysis and improvement
Technical Field
The invention relates to the technical field of UWB ranging, in particular to a method, a system and a storage medium for analyzing and improving UWB ranging errors.
Background
In the Ultra Wide Band (UWB) -based ranging and positioning algorithm, Time Difference of Arrival (TDOA) and Time of Arrival (TOA) methods are mainly classified. The TDOA location method requires all the location base stations to maintain strict time synchronization, and is difficult to implement in engineering. Therefore, UWB-based positioning methods typically employ TOA ranging algorithms. One-way ranging, two-way ranging, one-sided two-way ranging, and two-sided two-way ranging are the most commonly used ranging protocols for TOA estimation. Among them, bilateral-side Two-way Ranging (Double-side Two-way Ranging) is the most widely used in the industry. The basic principle of the algorithm is that a positioning tag and a plurality of base stations perform ranging operation (as shown in fig. 1), then, by triangulation, it is assumed that a triangle can be formed by a positioning tag point and a base station coordinate point, and the real-time coordinate of the positioning tag can be calculated by calculating the length of the triangle side to measure the angle formed by the base station and the positioning tag point, as shown in fig. 2. The essence of this is to calculate the distance by measuring the Time of Flight (TOF) of the signal between the transceiver nodes times the speed of light. Meanwhile, the distance measuring parties eliminate the distance measuring error caused by different clock errors of the two parties through the interaction of the signals twice. However, in the practical application process, after the ranging error of the ranging device caused by the clock error is eliminated, the ranging effect is still not ideal, and the positioning accuracy range is about 40cm under the environment without obstacles.
Through a lot of tests, the main sources of error generated in the UWB ranging process are as follows: 1) clock drift: during ranging, different timestamps need to be recorded by the transmission of the signal. In practical situations, due to the existence of objective factors (such as device material process, ambient temperature, etc.), the clock frequencies of the transceiver devices are slightly different, i.e. the clock drift phenomenon, and therefore the time information of the signals obtained by the receiver devices is inaccurate. 2) Error of read signal transmission and reception time: when the device reads the time stamp of signal transmission and reception, an error presenting a white noise distribution state exists, and the value is about (3E-10) seconds. If the time for a device to send a signal is t seconds, the signal sending time actually read by the device may be: any value between t- (3E-10) seconds to t + (3E-10) seconds. The equipment needs at least one information interaction for one-time ranging, namely, the equipment reads and writes 2 times respectively. Therefore, in the worst case, the error value is (3E-10) × 4 × C — 0.36 meters. Because the existing time drift correction algorithms are established on the basis that the equipment successfully reads the correct transceiving time, the time error generated by reading signals can cause the deviation of the clock drift correction process.
The above analysis shows that the original bilateral two-way ranging algorithm can only reduce the error caused by clock drift, but can not eliminate the error caused by the error of the time for receiving and transmitting the reading signal and the error of correcting the time offset caused by the error.
Disclosure of Invention
In view of this, the present invention provides an analysis and improvement method for UWB ranging errors, which can effectively reduce errors generated in a ranging process, thereby improving positioning accuracy.
To achieve the above object, a first aspect of the present invention provides an analysis and improvement method for UWB ranging error, comprising the steps of:
s101, performing n-wheel distance measurement signal interaction between first distance measurement equipment and second distance measurement equipment, wherein each wheel distance measurement signal interaction starts when the first distance measurement equipment sends a message to the second distance measurement equipment, and ends when the first distance measurement equipment receives a message replied by the second distance measurement equipment;
s102, respectively recording time points of the first ranging device and the second ranging device for sending and receiving messages;
s103, calculating a clock drift rate ratio based on the recorded time points;
s104, sequentially calculating the ranging result of each round in n rounds of signal interaction based on the clock drift rate ratio;
and S105, calculating a final ranging result based on the n-round ranging results.
Furthermore, in each round of signal interaction, the message replied by the second ranging device received by the first ranging device and the message sent by the first ranging device received by the second ranging device are filtered by the filter.
Further, the time points of each message transmission of the first ranging device are recorded As τ As1, τ As 2.,. tau Asn, and the time points of each message reception are recorded As τ Ar1, τ Ar 2.,. tau Arn; the second ranging apparatus transmits a message at each time point of τ Bs1, τ Bs 2.., τ Bsn, receives a message at each time point of τ Br1, τ Br 2.., τ Brn, calculates a clock drift rate ratio based on the recorded time points, the calculation formula of which is shown in formula (1),
W＝(τAsn-τAs1)/(τBrn-τBr1) (1)
wherein W is the clock drift rate ratio, and n is the number of signal interaction rounds.
Further, the sequentially calculating the result of each round of ranging in n rounds of signal interaction based on the clock drift rate ratio specifically includes:
calculating the time t elapsed from the transmission of a message by a first ranging device to the reception of a message by a second ranging deviceroundAn；
Calculating the time t from the second ranging device receiving the message sent by the first ranging device to the second ranging device replying to the messagereplyBn；
According to troundAn、treplyBnAnd calculating the signal flight duration of the corresponding turn according to the clock drift rate ratio, wherein n represents the signal interaction turn;
and calculating the ranging result of the corresponding turn according to the signal flight duration and the signal transmission speed.
Further, the step of calculating a final ranging result based on the n-round ranging results specifically includes the following steps:
and judging whether the number n of signal interaction rounds is an odd number, if the n is the odd number, calculating the final ranging result L by the formula (2):
L＝L(n+1)/2 (2)；
if n is an even number, the final ranging result is calculated by equation (3):
Figure BDA0003330873920000031
a second aspect of the invention provides a UWB range error analysis and improvement system, the system comprising: first range unit, second range unit, record module, first calculation module, second calculation module and third calculation module, wherein:
the first distance measuring equipment is used for carrying out n rounds of signal interaction with the second distance measuring equipment, wherein each round of signal interaction starts when the first distance measuring equipment sends a message to the second distance measuring equipment and ends when the first distance measuring equipment receives a message replied by the second distance measuring equipment;
the recording module is used for respectively recording the time points of the first ranging device and the second ranging device for sending and receiving the message;
the first calculating module is used for calculating a clock drift rate ratio based on the time points recorded by the recording module;
the second calculation module is used for sequentially calculating the ranging result of each round in n rounds of signal interaction based on the clock drift rate ratio;
and the third calculation module is used for calculating a final ranging result based on the results of the n-round ranging.
A third aspect of the invention provides a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the method of the first aspect described above.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention reduces the time drift error caused by the system by carrying out multi-round ranging signal interaction among the ranging devices;
2. by calculating the clock drift rate ratio, the multi-round ranging result is further calculated on the basis of the clock drift rate ratio, and the final ranging result is calculated according to the multi-round ranging result, so that the error caused by the fact that the equipment reads the transmitting and receiving signals is eliminated, and the positioning accuracy of the method provided by the invention is far superior to that of the traditional double-side double-distance ranging algorithm.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is apparent that the drawings in the following description are only preferred embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without inventive efforts.
Fig. 1 is a schematic diagram of a positioning tag and a plurality of base station ranging networking in the prior art.
Fig. 2 is a schematic diagram of TOA positioning principle in the prior art.
Fig. 3 is a schematic overall flow chart of an analysis and improvement method of UWB ranging error according to an embodiment of the present invention.
Fig. 4 is a schematic diagram illustrating a principle of an improved UWB ranging error method according to an embodiment of the present invention.
Fig. 5 is a schematic diagram of an overall structure of an analysis and improvement system for UWB ranging errors according to an embodiment of the present invention.
Fig. 6 is a diagram illustrating a ranging result of a one-way ranging algorithm in the prior art.
Fig. 7 is a diagram illustrating a ranging result of a two-way ranging algorithm in the prior art.
Fig. 8 is a schematic diagram of a ten-time mutual ranging result of the improved method according to the embodiment of the present invention.
Fig. 9 is a schematic diagram of a hundred-time interactive ranging result of the improved method according to the embodiment of the present invention.
In the figure, 1 a first distance measuring device, 2 a second distance measuring device, 3 a recording module, 4 a first calculating module, 5 a second calculating module, and 6 a third calculating module.
Detailed Description
The principles and features of this invention are described below in conjunction with the following drawings, the illustrated embodiments are provided to illustrate the invention and not to limit the scope of the invention.
Referring to fig. 3 and 4, the present embodiment provides an analysis and improvement method of UWB ranging error, the method including the steps of:
s101, the first distance measuring equipment and the second distance measuring equipment carry out n-wheel distance measuring signal interaction, wherein each wheel of distance measuring signal interaction starts when the first distance measuring equipment sends a message to the second distance measuring equipment, and ends when the first distance measuring equipment receives a message replied by the second distance measuring equipment.
Illustratively, the first ranging device first sends a message to the second ranging device, and the second ranging device replies the message to the first ranging device immediately after receiving the message, and the process is repeated for n rounds. The messages received by the first ranging device and the second ranging device are filtered through the filter, so that excessive noise interference is filtered.
And S102, respectively recording the time points of the first ranging device and the second ranging device for sending and receiving the message.
And S103, calculating the clock drift rate ratio based on the recorded time points.
And S104, sequentially calculating the ranging result of each round in the n rounds of signal interaction based on the clock drift rate ratio.
And S105, calculating a final ranging result based on the n-round ranging results.
Specifically, in step S102, time points of each message transmission by the first ranging device are sequentially recorded As τ As1, τ As 2.. and τ Asn, and time points of each message reception by the first ranging device are sequentially recorded As τ Ar1, τ Ar 2.. and τ Arn. And sequentially recording the time points of each message transmission of the second ranging device as tau Bs1, tau Bs 2.., tau Bsn, and sequentially recording the time points of each message reception of the second ranging device as tau Br1, tau Br 2.., tau Brn. In step S103, a clock drift rate ratio is calculated based on the recorded time points, the calculation formula is shown in formula (1),
W＝(τAsn-τAs1)/(τBrn-τBr1) (1)
wherein W is the clock drift rate ratio, and n is the number of signal interaction rounds.
In step S104, sequentially calculating a result of each round of ranging in n-round ranging signal interaction based on the clock drift rate ratio, specifically including the following steps:
calculating the time t elapsed from the transmission of a message by a first ranging device to the reception of a message by a second ranging deviceroundAnAs shown in the following formula:
troundAn＝τArn-τAsn
wherein n represents the run, τArnFor the time point, τ, at which the first ranging device of the round receives the messageAsnThe point in time at which the first ranging device sent the message for that round.
Calculating reception of the second ranging deviceTime t from message sent by one ranging device to reply message of second ranging devicereplyBnAs shown in the following formula:
treplyBn＝τBsn-τBrn
wherein n represents the run, τBrnFor the time point, τ, at which the second ranging device receives the message in the roundBsnThe point in time at which the second ranging device sent the message for that round.
According to troundAn、treplyBnCalculating the signal flight duration, signal flight duration T, of the corresponding turn according to the clock drift rate ratiotofIs represented by the following formula:
Ttof＝(troundAn–treplyBn*W)/2
calculating the distance measurement result of the corresponding turn according to the signal flight duration and the signal transmission speed, and calculating the distance measurement result L of the nth turnnIs represented by the following formula:
Ln＝Ttof*C
where C represents the signal transmission speed, in this embodiment C takes the value of the speed of light.
In step S105, the calculating a final ranging result based on the n-round ranging results specifically includes the following steps:
and judging whether the number n of signal interaction rounds is an odd number, if the n is the odd number, calculating the final ranging result L by the formula (2):
L＝L(n+1)/2 (2)
namely, when the number of the interaction rounds of the ranging signals is an odd number, the median of the multi-round ranging results is taken as the final ranging result.
If n is an even number, the final ranging result is calculated by equation (3):
Figure BDA0003330873920000071
as an optional implementation manner, in the process of executing the method described in the foregoing embodiment, it is further detected whether the moving speed of the positioning tag itself exceeds a preset threshold, and if the moving speed exceeds the preset threshold, a prompt message is sent and the execution method is terminated, because if the positioning tag itself is in a high-speed moving state, the ranging process loses meaning.
In a specific embodiment of the invention, the method is tested in an actual environment, wherein the test result is shown in table 1, when the number of times of interaction of the ranging signals is 10, each ranging takes 25 milliseconds, and the positioning accuracy is within 0.05 meter, so that the method is suitable for positioning the robot when the robot moves. When the number of the distance measurement signal interaction is 100, each distance measurement takes 250 milliseconds, the positioning precision is within 0.03 meter, and the method is suitable for positioning the robot when the robot is static.
Table 1 results of the algorithmic testing provided in this example
Number of signal interactions n Time consumed for each ranging Accuracy of measurement Suitable scene
10 25ms 0.05m When the robot is in motion
100 250ms 0.03m When the robot is at rest
Referring to fig. 6 to 9, the ranging results of the one-way ranging algorithm in fig. 6 and the two-way ranging algorithm in fig. 7 both have large fluctuation and large error, and it can be seen from fig. 8 and 9 that the ranging results of the method provided by this embodiment are more stable and have smaller error than those of the two algorithms, and meanwhile, the results of the hundred interactions are more stable than those of the ten interactions, and it can also be seen from table 2 that the mean square deviations of the ten interactions and the hundred interactions of the improved algorithm provided by this embodiment are 0.00857 and 0.0044878, which are both much smaller than the mean square deviations of the ranging results of the one-way ranging algorithm and the two-way ranging algorithm, which indicates that the ranging results have small fluctuation and relatively small error.
TABLE 2 measurement of distance result values
Figure BDA0003330873920000081
According to the method provided by the embodiment, most of the distance measurement errors caused by different clock errors of the two sides are successfully eliminated by means of multiple signal interaction of the two sides, the positioning accuracy is improved to be within 0.03 meter from 0.4 meter, and the method is greatly improved compared with the traditional bilateral double-distance algorithm.
Based on the same inventive concept as the previous method embodiment, another embodiment of the present invention provides a UWB ranging error analysis and improvement system, which, with reference to fig. 5, comprises a first ranging apparatus 1, a second ranging apparatus 2, a recording module 3, a first calculating module 4, a second calculating module 5 and a third calculating module 6, wherein:
the first distance measuring equipment 1 is used for carrying out n rounds of signal interaction with the second distance measuring equipment 2, wherein each round of signal interaction starts when the first distance measuring equipment 1 sends a message to the second distance measuring equipment 2, and ends when the first distance measuring equipment 1 receives a message replied by the second distance measuring equipment 2.
The recording module 3 is configured to record time points when the first ranging device 1 and the second ranging device 2 send and receive messages, respectively.
The first calculation module 4 is configured to calculate the clock drift rate ratio based on the time points recorded by the recording module.
And the second calculating module 5 is used for sequentially calculating the ranging result of each round in n rounds of signal interaction based on the clock drift rate ratio.
The third calculating module 6 is used for calculating a final ranging result based on the results of the n-round ranging.
The system is configured to implement the method described in the foregoing method embodiment, and both the working principle and the technical effect of the system may refer to the foregoing method embodiment, which is not described herein again.
Another embodiment of the present invention also provides a computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, implements the method of the aforementioned method embodiment.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (7)

1. A method for UWB ranging error analysis and improvement, the method comprising the steps of:
s101, performing n-wheel distance measurement signal interaction between first distance measurement equipment and second distance measurement equipment, wherein each wheel distance measurement signal interaction starts when the first distance measurement equipment sends a message to the second distance measurement equipment, and ends when the first distance measurement equipment receives a message replied by the second distance measurement equipment;
s102, respectively recording time points of the first ranging device and the second ranging device for sending and receiving messages;
s103, calculating a clock drift rate ratio based on the recorded time points;
s104, sequentially calculating the ranging result of each round in n rounds of signal interaction based on the clock drift rate ratio;
and S105, calculating a final ranging result based on the n-round ranging results.
2. The method of claim 1 wherein the messages received from the first ranging device in response to the second ranging device and the messages received from the second ranging device in response to the first ranging device are filtered by the filter for each signal interaction.
3. A method of analysing and refining UWB range errors according to claim 1, characterized in that the time points of each message transmission by the first ranging device are recorded As τ As1, τ As 2.., τ Asn, and the time points of each message reception are τ Ar1, τ Ar 2.., τ Arn; the second ranging apparatus transmits a message at each time point of τ Bs1, τ Bs 2.., τ Bsn, receives a message at each time point of τ Br1, τ Br 2.., τ Brn, calculates a clock drift rate ratio based on the recorded time points, the calculation formula of which is shown in formula (1),
W＝(τAsn-τAs1)/(τBrn-τBr1) (1)
wherein W is the clock drift rate ratio, and n is the number of signal interaction rounds.
4. The method as claimed in claim 3, wherein the step of sequentially calculating the ranging result for each of n signal interactions based on the clock drift ratio comprises:
calculating the time t elapsed from the transmission of a message by a first ranging device to the reception of a message by a second ranging deviceroundAn；
Calculating the time t from the second ranging device receiving the message sent by the first ranging device to the second ranging device replying to the messagereplyBn；
According to troundAn、treplyBnAnd calculating the signal flight duration of the corresponding turn according to the clock drift rate ratio, wherein n represents the signal interaction turn;
and calculating the ranging result of the corresponding turn according to the signal flight duration and the signal transmission speed.
5. The method for analyzing and improving UWB ranging error of claim 1, wherein the final ranging result is calculated based on the results of n-round ranging, comprising the following steps:
and judging whether the number n of signal interaction rounds is an odd number, if the n is the odd number, calculating the final ranging result L by the formula (2):
L＝L(n+1)/2 (2)；
if n is an even number, the final ranging result L is calculated by equation (3):
Figure FDA0003330873910000021
6. an analysis and improvement system of UWB ranging error, characterized in that, the system includes first range finding equipment, second range finding equipment, record module, first calculation module, second calculation module and third calculation module, wherein:
the first distance measuring equipment is used for carrying out n rounds of signal interaction with the second distance measuring equipment, wherein each round of signal interaction starts when the first distance measuring equipment sends a message to the second distance measuring equipment and ends when the first distance measuring equipment receives a message replied by the second distance measuring equipment;
the recording module is used for respectively recording the time points of the first ranging device and the second ranging device for sending and receiving the message;
the first calculating module is used for calculating a clock drift rate ratio based on the time points recorded by the recording module;
the second calculation module is used for sequentially calculating the ranging result of each round in n rounds of signal interaction based on the clock drift rate ratio;
and the third calculation module is used for calculating a final ranging result based on the results of the n-round ranging.
7. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the method of any one of claims 1-5.
CN202111280398.5A 2021-11-01 2021-11-01 Method, system and storage medium for UWB ranging error analysis and improvement Pending CN114063049A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023225962A1 (en) * 2022-05-26 2023-11-30 华为技术有限公司 Distance measurement method and related apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023225962A1 (en) * 2022-05-26 2023-11-30 华为技术有限公司 Distance measurement method and related apparatus

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