Ultra-wideband positioning method based on AOA / PDOA / TDOA fusion angle measurement

Abstract

The invention provides an ultra-wideband positioning method based on AOA / PDOA / TDOA fusion angle measurement. According to the method, the time difference, the phase difference and the arrival angle of a signal reaching a base station are obtained, a TDOA method is used for calculating a target position reference coordinate, a reference angle is obtained, under the condition that the base station interval is larger than the signal frequency half-wavelength, a series of target angles are calculated through PDOA, and a target position reference angle is obtained through an AOA method; selecting a plurality of fuzzy solutions close to the reference angle from a series of angles of the PDOA method by using the reference angle obtained by the TDOA method; weighting and averaging the plurality of solutions by using a weighting algorithm to obtain a final solution; according to the method, the defects that the precision of traditional TDOA long-distance measurement is remarkably reduced and the precision of traditional AOA lateral angle measurement is poor are overcome at the same time, the limitation of the distance between base stations on traditional PDOA is relieved, and the angle measurement precision higher than the angle measurement precision of the method and the angle measurement precision of the combination of every two methods are obtained; the method provided by the invention can be applied to measuring the angle between the target position and the base station in two-dimensional and three-dimensional positioning systems.

Description

Technical Field

[0001] The present invention belongs to the field of indoor positioning and is a new ultra-wideband positioning method which integrates the advantages of AOA, PDOA and TDOA to achieve high-precision angle measurement. Background Art

[0002] With the increase of human indoor activities, the demand for indoor positioning is becoming more and more extensive. Various wireless positioning indoor services such as Bluetooth, WIFI, ZigBee, Near Field Communication (NFC) and Ultra Wideband (UWB) are emerging. Among these indoor positioning technologies, UWB positioning is considered to be one of the most promising wireless collaborative indoor positioning solutions. Ultra Wideband technology has been widely used in indoor positioning systems due to its low power consumption, high transmission rate and strong penetration.

[0003] At present, the basic ultra-wideband positioning methods that have been proposed are: TOA positioning, TDOA positioning, RSS positioning, AOA positioning and PDOA positioning. Among them, the AOA positioning method is the first positioning method based on the signal arrival angle. Due to the high requirements on the directivity of the antenna array, the angle measurement accuracy in the normal direction is usually better than that in the lateral direction. After that, the PDOA positioning method was proposed. This is a positioning method based on the phase difference of signal arrival. It measures the angle by the phase difference of the signal arriving at the two base stations. It can overcome the problem that the angle measurement accuracy of other methods gradually decreases as the distance between the tag and the base station becomes farther. However, this method requires that the distance between base stations is much smaller than half the wavelength of the corresponding frequency, otherwise there will be a multiple solution problem. The limitation of the distance between base stations affects the scope of application of this method. The TDOA method realizes positioning through the time difference between the signal arriving at the two base stations. Within the working range, this method has the highest angle measurement accuracy among the five methods, but when the distance between the tag and the base station is much larger than the distance between the base stations, the angle measurement accuracy will drop significantly.

[0004] In general, the above three methods of angle measurement have their own advantages and disadvantages. Therefore, a new method that integrates the technical advantages of the three angle measurement methods is proposed, which can greatly improve the angle measurement accuracy of ultra-wideband positioning, thereby greatly improving the positioning accuracy. Summary of the invention

[0005] The object of the present invention is to provide an ultra-wideband positioning method based on AOA / PDOA / TDOA fusion angle measurement.

[0006] To achieve the above-mentioned purpose of the invention, the technical solution of the present invention is as follows:

[0007] In the method, the TDOA method is used to calculate the reference coordinates of the target position using the time difference of the signal reaching the base station, and then a reference angle is obtained; the PDOA method is used in the method to calculate the target position angle using the phase difference of the signal reaching the base station, and a series of angles are calculated when the distance between base stations is greater than the half wavelength corresponding to the signal frequency; the AOA method is used in the method to obtain a reference angle of the target position using the directivity of the base station antenna. Further, the method uses the reference angle obtained by the TDOA method to select several angle fuzzy solutions close to the reference angle from a series of angles calculated by the PDOA method. Finally, the method uses a weighted algorithm to weighted average several solutions obtained by the TDOA method, the PDOA method, and the AOA method to obtain the final solution. It should be noted that the final solution obtained by weighted averaging in the method is the relative angle between the target position coordinates and the base station. Combined with the distance between the target position coordinates and the base station obtained by the time the signal reaches the base station, the coordinates of the target position relative to the base station can be solved.

[0008] In the method, the method of selecting several angle ambiguity solutions from a series of angles obtained by the PDOA method is as follows: according to the characteristic that the measurement accuracy of the TDOA method decreases as the target distance increases, as the measured signal arrival time increases, the reference angle is obtained using the TDOA method, and the range of the angle ambiguity solution close to the reference angle is increased by selecting several angles from a series of angles calculated by the PDOA method.

[0009] In the method, the method of using a weighted algorithm to weight and average several solutions obtained by the TDOA method, the PDOA method, and the AOA method to obtain the final solution is as follows: when the long-distance target position coordinates calculated by the TDOA method exceed the target position range, the target position angle obtained by the AOA method has a weight of 1 in the weighted algorithm. According to the characteristic that the measurement accuracy of the TDOA method decreases as the target distance increases, as the measured signal arrival time increases, the weight of the target position angle obtained by the TDOA method and the PDOA method in the weighted algorithm decreases. According to the characteristic that the angle measurement accuracy of the AOA method gradually decreases from the normal to the lateral accuracy, as the angle increases from the normal to the lateral, the weight of the target position angle obtained by the AOA method in the weighted algorithm decreases.

[0010] On the one hand, the angle measurement error of the AOA method increases monotonically with the degree of deviation from the normal direction. On the other hand, the angle measurement error caused by jitter in the PDOA method satisfies:

[0011]

[0012] The above formula shows that the shorter the baseline, the greater the angle measurement error caused by jitter. In the method, the TDOA method is used to deambiguate the multiple solutions of the PDOA method of the base station that is more than half a wavelength away, so that the PDOA method base station used in the method becomes longer, reducing the angle measurement error caused by jitter.

[0013] The above two aspects illustrate the effectiveness of the method in principle.

[0014] The innovation of the present invention lies in that by integrating the high-precision angle measurement performance of the three angle measurement methods of TDOA, PDOA and AOA within a certain range, the defect of the three methods that the angle measurement accuracy is significantly reduced within certain ranges is avoided, and the advantages of each method are combined to solve the shortcomings of the traditional TDOA long-distance measurement accuracy being significantly reduced and the traditional AOA lateral angle measurement accuracy being poor, and the traditional PDOA method is freed from the limitation of the distance between base stations. The full-range angle measurement accuracy is better than the angle measurement performance of the three single methods and their two-by-two combinations.

[0015] Compared with the prior art, the present invention has the following significant advantages: 1) The method eliminates the limitation of the traditional PDOA method on the distance between base stations, and can be used when the distance between base stations is much larger than half a wavelength, greatly broadening the application scenarios of the method; 2) The method also solves the defects of the significant decrease in the long-distance measurement accuracy of the traditional TDOA and the poor lateral angle measurement accuracy of the traditional AOA at one time, and can still maintain a certain angle measurement accuracy at a longer distance and in the lateral direction; 3) The method maintains high-precision angle measurement characteristics over a larger range.

[0016] The present invention is described in further detail below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the solution process of the method of the present invention;

[0018] Figure 2 This is a schematic diagram of the positioning effect of an embodiment of the ultra-wideband positioning method based on AOA / PDOA / TDOA fusion angle measurement according to the present invention applied to 500 targets at random positions;

[0019] Figure 3 This is a schematic diagram of the angle measurement result error of an embodiment of the ultra-wideband positioning method based on AOA / PDOA / TDOA fusion angle measurement of the present invention applied to 500 targets at random positions;

[0020] Figure 4 This is a schematic diagram of the angle measurement error of the embodiment of the traditional TDOA method applied to 500 randomly located targets;

[0021] Figure 5This is a schematic diagram of the angle measurement error of the embodiment of the traditional PDOA method applied to 500 random position targets;

[0022] Figure 6 This is a schematic diagram of the angle measurement error of an embodiment of the traditional AOA method applied to 500 random position targets; DETAILED DESCRIPTION

[0023] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0024] Figure 1 The flowchart of the ultra-wideband positioning method based on AOA / PDOA / TDOA fusion angle measurement proposed by the present invention is given. Based on this flowchart, an embodiment is now given. This embodiment is applicable to the situation of measuring the angle between the target position and the base station in a two-dimensional positioning system. The method can be executed by a main base station with data processing capabilities. In this embodiment, the two-dimensional positioning system is implemented using four base stations whose coordinate positions are arranged in a parallelogram. In this embodiment, the method of the present invention is applied to the angle measurement of 500 random position targets, and then the coordinates of all target positions are obtained according to the target distance, such as Figure 2 shown.

[0025] In this embodiment, when the distance between the target and the reference base station calculated by the TDOA method is less than the distance between the two base stations, several angle ambiguity solutions close to the reference angle obtained by the TDOA method are selected from a series of angles calculated by the PDOA method, and the range of the angle ambiguity solutions is plus or minus zero degrees; when the distance between the target and the reference base station calculated by the TDOA method is greater than the distance between the two base stations and less than twice the distance between the two base stations, several angle ambiguity solutions close to the reference angle obtained by the TDOA method are selected from a series of angles calculated by the PDOA method, and the range of the angle ambiguity solutions is plus or minus three degrees; when the distance between the target and the reference base station calculated by the TDOA method is greater than twice the distance between the two base stations, several angle ambiguity solutions close to the reference angle obtained by the TDOA method are selected from a series of angles calculated by the PDOA method, and the range of the angle ambiguity solutions is plus or minus five degrees.

[0026] In this embodiment, ten angle ambiguity solutions are selected from a series of angles solved by the PDOA method that are close to the reference angle obtained by the TDOA method.

[0027] In this embodiment, when the distance between the target and the reference base station calculated by the TDOA method is greater than the distance between the two base stations and less than twice the distance between the two base stations, and when the angle between the target and the reference base station calculated by the AOA method is less than ten degrees, the weight of the target position angle obtained by the AOA method in the weighted algorithm is 1; when the angle between the target and the reference base station calculated by the AOA method is greater than ten degrees and less than twenty degrees, the weight of the target position angle obtained by the AOA method in the weighted algorithm is 0.9, and the weight of the target position angle obtained by the TDOA method and the PDOA method in the weighted algorithm is 0. 1; when the angle range between the target calculated by the AOA method and the reference base station increases by ten degrees, the weight of the target position angle obtained by the AOA method in the weighted algorithm decreases by 0.1, and the weight of the target position angle obtained by the TDOA method and the PDOA method in the weighted algorithm increases by 0.1; when the angle between the target calculated by the AOA method and the reference base station is greater than eighty degrees and less than ninety degrees, the weight of the target position angle obtained by the AOA method in the weighted algorithm is 0.1, and the weight of the target position angle obtained by the TDOA method and the PDOA method in the weighted algorithm is 0.9.

[0028] In this embodiment, when the distance between the target and the reference base station calculated by the TDOA method is greater than twice the distance between the two base stations, and when the angle between the target and the reference base station calculated by the AOA method is less than ten degrees, the target position angle obtained by the AOA method has a weight of 0.9 in the weighted algorithm, and the target position angle obtained by the TDOA method and the PDOA method has a weight of 0.1 in the weighted algorithm; when the angle between the target and the reference base station calculated by the AOA method is greater than ten degrees and less than twenty degrees, the target position angle obtained by the AOA method has a weight of 0.8 in the weighted algorithm, and the target position angle obtained by the TDOA method and the PDOA method has a weight of 0.1 in the weighted algorithm. The weight of the target position angle in the weighted algorithm is 0.2; when the angle range between the target and the reference base station calculated by the AOA method increases by ten degrees, the weight of the target position angle obtained by the AOA method in the weighted algorithm decreases by 0.1, and the weight of the target position angle obtained by the TDOA method and the PDOA method in the weighted algorithm increases by 0.1; when the angle between the target and the reference base station calculated by the AOA method is greater than eighty degrees and less than ninety degrees, the weight of the target position angle obtained by the AOA method in the weighted algorithm is 0.1, and the weight of the target position angle obtained by the TDOA method and the PDOA method in the weighted algorithm is 0.9.

[0029] In this embodiment, if Figure 3 , Figure 4 , Figure 5 , Figure 6As shown in the figure, the angle measurement results of the ultra-wideband positioning method based on AOA / PDOA / TDOA fusion angle measurement of 500 random position targets are better than those of the traditional TDOA, PDOA and AOA methods, which shows that the method of the present invention is effective.

[0030] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An ultra-wideband positioning method based on AOA / PDOA / TDOA fusion angle measurement, including angle measurement methods of three positioning methods: TDOA, PDOA, and AOA. The method can achieve high-precision angle measurement at close range and reduce long-distance angle measurement errors. The method obtains the time difference, phase difference and arrival angle of the signal arriving at the base station through the base station; The method uses the TDOA method to calculate the reference coordinates of the target position using the time difference of the signal arriving at the base station, and then obtains a reference angle; The method uses the PDOA method to calculate the target position angle using the phase difference of the signal reaching the base station, and calculates a series of angles when the base station spacing is greater than the half wavelength corresponding to the signal frequency; The method uses the AOA method to obtain a reference angle of a target position by utilizing the directivity of the base station antenna.

2. The ultra-wideband positioning method based on AOA / PDOA / TDOA fusion angle measurement according to claim 1, characterized in that: Using the reference angle obtained by the TDOA method, several angle ambiguity solutions close to the reference angle are selected from a series of angles solved by the PDOA method.

3. The ultra-wideband positioning method based on AOA / PDOA / TDOA fusion angle measurement according to claim 1 or 2, characterized in that: The method uses a weighted algorithm to weight and average several solutions obtained by the TDOA method, the PDOA method, and the AOA method to obtain a final solution.

4. The ultra-wideband positioning method based on AOA / PDOA / TDOA fusion angle measurement according to claim 1 or 2, characterized in that: As the arrival time of the measured signal increases, the reference angle is obtained using the TDOA method, and the range of the angle ambiguity solution is increased by selecting several angles close to the reference angle from a series of angles solved by the PDOA method.

5. The ultra-wideband positioning method based on AOA / PDOA / TDOA fusion angle measurement according to claim 3, characterized in that: When the long-distance target position coordinates calculated by the TDOA method exceed the target position range, the target position angle obtained by the AOA method has a weight of 1 in the weighted algorithm.

6. The ultra-wideband positioning method based on AOA / PDOA / TDOA fusion angle measurement according to claim 3, characterized in that: As the measured signal arrival time increases, the weight of the target position angle obtained by the TDOA method and the PDOA method in the weighted algorithm decreases.

7. The ultra-wideband positioning method based on AOA / PDOA / TDOA fusion angle measurement according to claim 3, characterized in that: As the angle increases from the normal to the lateral direction, the weight of the target position angle obtained by the AOA method in the weighted algorithm decreases.

8. An ultra-wideband positioning method based on AOA / PDOA / TDOA fusion angle measurement according to any one of claims 5 to 7, characterized in that: The final solution obtained by weighted averaging is the relative angle between the target position coordinates and the base station. Combined with the distance between the target position coordinates and the base station obtained by the time the signal reaches the base station, the coordinates of the target position relative to the base station can be solved.

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