A self-closed loop positioning method based on motion characteristics of a Beidou micro base station

Abstract

The application relates to the field of indoor navigation and discloses a self-closed loop positioning method based on the motion characteristics of a Beidou micro base station. The current working mode of a receiving terminal is to capture and track a Beidou micro base station signal first, and then output ranging information after the tracking is stable. However, due to the complex diversity of indoor space, the receiving terminal is affected by the signal near-far effect and multipath, and the original observation data output by the receiver is generally superimposed with serious environmental noise error, so that the receiver is difficult to give a single point positioning result according to the conventional navigation algorithm in a narrow space, and it is more difficult to realize the fixing of the integer ambiguity, so that the receiver is difficult to realize positioning in the environment. The application discloses a self-closed loop positioning method based on the motion characteristics of a Beidou micro base station, which effectively realizes the acquisition of the accurate calibration point position by utilizing the characteristics of the Doppler ambiguity and the extreme value characteristics of the Doppler difference, and effectively improves the positioning continuity and positioning accuracy of the terminal.

Description

Technical Field

[0001] This invention relates to the field of indoor navigation, and mainly addresses the positioning problem of Beidou micro base stations in narrow indoor and underground spaces. Background Technology

[0002] Beidou micro base stations are a low-cost and easy-to-deploy navigation and positioning platform. In situations where the visibility of some navigation satellites is reduced or satellite navigation signals are interfered with, deploying Beidou micro base stations can provide navigation services to users in specific areas even when satellite navigation service performance is degraded. The Beidou micro base station positioning system has the following advantages: (1) Strong anti-interference capability. Beidou micro base stations are generally deployed near the receiver, so the navigation signal strength received by the receiver is relatively high, making Beidou micro base stations more resistant to interference than GNSS satellites; (2) Flexible networking. During the positioning process, the location and number of Beidou micro base stations can be selected according to positioning needs and environment; (3) Simple equipment and low cost. Compared with the currently operating GNSS positioning system, the equipment of Beidou micro base stations is simpler and less expensive. Therefore, researching the technology of using Beidou micro base stations for indoor spatial positioning is a feasible and widely applicable technology.

[0003] However, current receivers operate by first capturing and tracking the BeiDou micro base station signal, and only outputting ranging information after the tracking stabilizes. Due to the complexity and diversity of indoor spaces, receivers are affected by signal distance effects and multipath propagation. The raw observation data output by the receiver is generally superimposed with severe environmental noise errors, making it difficult for the receiver to provide single-point positioning results using conventional navigation algorithms in narrow spaces. Furthermore, it is even more difficult to fix integer ambiguity, making positioning difficult in such environments. Summary of the Invention

[0004] To address the current problems, this invention proposes a self-closed-loop positioning method based on the motion characteristics of BeiDou micro base stations. This method is simple and efficient, not only avoiding the current difficulties faced by BeiDou micro base stations in narrow spaces, but also providing continuous positioning results with a measured accuracy of 2-3 meters.

[0005] To achieve the above objectives, the technical solution adopted is as follows:

[0006] A self-closed-loop positioning method based on the motion characteristics of BeiDou micro base stations specifically includes the following process:

[0007] Step 1: In a narrow space, four Beidou micro base stations are deployed horizontally in two rows. Each array broadcasts one Beidou micro base station signal in real time. The coverage area of ​​the Beidou micro base stations is divided into three zones: signal pre-acquisition zone, position calibration zone, and continuous positioning zone.

[0008] Step 2: The receiver acquires the speed information broadcast by the Beidou micro base station in real time from the moment it enters the pre-acquisition domain, and reflects it in the raw observation data to obtain four Doppler values; and judges the magnitude and change characteristics of the Doppler values ​​in real time. When the change characteristics of the four signals are consistent, the Doppler values ​​meet the requirements of real-time monitoring and proceed to the next step of processing.

[0009] Step 3: The receiver performs difference processing on the Doppler values ​​of the real-time dot matrix signal to obtain four sets of Doppler difference values;

[0010] Step 4: When the receiver moves to the center position of the four doppler arrays, all four sets of Doppler difference feature quantities show maximum feature values. Based on the correspondence between the maximum feature values ​​and the position, the accurate position coordinates of the receiver at the current moment are obtained, and its own position is corrected.

[0011] Step 5: When the receiver moves to the center position of the four dot matrix, based on the characteristic that the Doppler values ​​generated by the two Beidou micro base stations on the same longitudinal side are the same in magnitude but opposite in direction, the Doppler value at the center position is obtained, and the velocity at the center position at the current moment is obtained based on the relationship between the Doppler value and the velocity.

[0012] Step 6: Based on the obtained accurate position and velocity values, and by utilizing the relationship between position changes and velocity at different times, the real-time position information at each moment is obtained sequentially.

[0013] Furthermore, in the second step, when the relationship between the instantaneous Doppler value and the mean is less than a set value, it is determined that the four sets of Doppler values ​​meet the requirements for real-time monitoring.

[0014] Furthermore, the correspondence between the maximum eigenvalues ​​and their positions in the fourth step is shown in the following formula:

[0015]

[0016] In the formula, v is the velocity, L is the distance between the points in the radial direction, x is the position coordinate of the points in the radial direction, h is the height of the point array antenna, λ is the wavelength of the signal, and DF is the Doppler difference.

[0017] Furthermore, in the fourth step, peak detection begins when the Doppler difference exceeds the threshold. The Doppler difference at the current moment is judged in real time. If the current value is greater than the value at the previous moment, the maximum feature value is updated to the current value. If the current value is less than the value at the previous moment, the value at the previous moment is the maximum feature value. Thus, the center positions of the four lattice points are obtained.

[0018] Furthermore, in step five, the actual Doppler value at the center position is...

[0019]

[0020] Where Δf is the clock difference between the BeiDou micro base station and the receiver, Δf = mean(dp) i ), dop i dp represents the true Doppler value produced by velocity. i is the actual Doppler value, and i is the current time.

[0021] The present invention has the following advantages over the prior art:

[0022] This invention fully leverages the advantages of BeiDou micro base stations, such as the absence of ambiguity and high stability of Doppler values. By extracting Doppler difference features, it accurately achieves receiver position acquisition in narrow spaces. Furthermore, by utilizing the motion characteristics of Doppler, it enables continuous positioning of BeiDou micro base stations in narrow spaces using single-parameter features. Attached Figure Description

[0023] Figure 1 This is a scene diagram of the deployment of the Beidou micro base station system in a narrow space according to the present invention.

[0024] Figure 2 This is a diagram showing the relationship between the characteristic parameters and location of the Beidou micro base station of this invention. Detailed Implementation

[0025] The invention will be further explained below with reference to the accompanying drawings.

[0026] A self-closed-loop positioning method based on the motion characteristics of BeiDou micro base stations specifically includes the following process:

[0027] Step 1: In a narrow space, four Beidou micro base station arrays are arranged horizontally in two rows. Each array broadcasts one Beidou micro base station signal in real time. The coverage area of ​​the Beidou micro base station is divided into three zones: signal pre-acquisition zone, position calibration zone, and continuous positioning zone.

[0028] Step 2: The receiver acquires the speed information broadcast by the BeiDou micro base station in real time from the moment it enters the pre-acquisition domain. This information is reflected in the raw observation data as Doppler values. Therefore, according to... Figure 1 The receiver can acquire four characteristic values: dop1, dop2, dop3, and dop4; and determine the magnitude and variation characteristics of the Doppler value in real time. When the variation characteristics of the four signals are consistent, the Doppler value meets the requirements for real-time monitoring and proceeds to the next step of processing.

[0029] Step 3: The receiver performs difference processing on the Doppler values ​​of the real-time dot matrix signal to obtain four sets of Doppler difference values;

[0030] The real-time Doppler and Doppler difference data are obtained as follows:

[0031]

[0032]

[0033] Where i represents the current time.

[0034] Step 4: When the receiver moves to the center position of the four doppler arrays, all four sets of Doppler difference feature quantities show maximum feature values. Based on the correspondence between the maximum feature values ​​and the position, the accurate position coordinates of the receiver at the current moment are obtained, and its own position is corrected.

[0035] According to the above process description, under normal circumstances, the relationship between the Doppler difference and the peak value in a narrow space is approximately twice the Doppler difference, such as... Figure 2 As shown, without considering motion speed and signal wavelength, a detection threshold of 1.1 is set here. When the Doppler difference exceeds the threshold, peak detection begins, and the Doppler difference at the current moment is judged in real time. If the current value is greater than the value at the previous moment, the extreme value DF is then determined. max The value is updated to the current value. If the current value is less than the value at the previous time step, then the value at the previous time step is the extreme value. This allows us to determine the center positions of the four points.

[0036] Step 5: Obtain the Doppler value of the reference point location. Typically, due to the time-frequency difference between the BeiDou micro base station and the receiver, the actual Doppler information we obtain is...

[0037] dp i =Δf+dop i

[0038] Where Δf is the clock difference between the BeiDou micro base station and the receiver, and dop i dp is the Doppler value generated by velocity. i This represents the actual Doppler information. Therefore, the actual Doppler information can be restated as...

[0039]

[0040] Since this is the midpoint, the Doppler values ​​between points 1 and 2, and between points 3 and 4, are the same in magnitude but opposite in direction. Therefore...

[0041]

[0042] Therefore, summing the radial directions 1 and 2, and 3 and 4 respectively, yields...

[0043]

[0044] Therefore, the fixed clock difference Δf is mean(dp) i )

[0045] Therefore, the true Doppler value is obtained.

[0046]

[0047] Based on the correspondence between velocity and Doppler, we can obtain the current velocity value in real time;

[0048] The sixth step involves using the obtained accurate position and velocity values, and the relationship between position changes and velocity v at different times, to sequentially derive the real-time position information s at each moment. k =s k-1 +vΔt.

[0049] The above description is only a specific example of the present invention, but the scope of protection of the present invention is not limited thereto. Within the technical scope disclosed in the present invention, all conceivable variations should be included within the scope of the present invention.

Claims

1. A self-closed-loop positioning method based on the motion characteristics of BeiDou micro base stations, characterized in that, Specifically, the process includes the following: Step 1: In a narrow space, four Beidou micro base stations are deployed horizontally in two rows. Each array broadcasts one Beidou micro base station signal in real time. The coverage area of ​​the Beidou micro base stations is divided into three zones: signal pre-acquisition zone, position calibration zone, and continuous positioning zone. Step 2: The receiver acquires the speed information broadcast by the Beidou micro base station in real time from the moment it enters the pre-acquisition domain, and reflects it in the raw observation data to obtain four Doppler values; It also determines the magnitude and variation characteristics of the Doppler value in real time. When the variation characteristics of the four signals are consistent, the Doppler value meets the requirements for real-time monitoring and proceeds to the next step of processing. Step 3: The receiver performs difference processing on the Doppler values ​​of the real-time dot matrix signal to obtain four sets of Doppler difference values; Step 4: When the receiver moves to the center position of the four doppler arrays, all four sets of Doppler difference feature quantities show maximum feature values. Based on the correspondence between the maximum feature values ​​and the position, the accurate position coordinates of the receiver at the current moment are obtained, and its own position is corrected. Step 5: When the receiver moves to the center position of the four dot matrix, based on the characteristic that the Doppler values ​​generated by the two Beidou micro base stations on the same longitudinal side are the same in magnitude but opposite in direction, the Doppler value at the center position is obtained, and the velocity at the center position at the current moment is obtained based on the relationship between the Doppler value and the velocity. Step 6: Based on the obtained accurate position and velocity values, and by utilizing the relationship between position changes and velocity at different times, the real-time position information at each moment is obtained sequentially. The correspondence between the maximum eigenvalue and its location in the fourth step is shown in the following formula: In the formula, Let L be the velocity, and L be the distance between points in the radial direction. These are the position coordinates in the radial direction between arrays. The height for mounting the array antenna, The wavelength of the signal. This represents the Doppler difference. In step five, the actual Doppler value at the center position is: In the formula, The clock difference between the BeiDou micro base station and the receiver. = , The true Doppler value produced by velocity, This is the actual Doppler value. This refers to the current moment.

2. The self-closed-loop positioning method based on the motion characteristics of Beidou micro base stations according to claim 1, characterized in that, In the second step, when the relationship between the instantaneous Doppler value and the mean is less than the set value, it is determined that the four sets of Doppler values ​​meet the requirements for real-time monitoring.

3. The self-closed-loop positioning method based on the motion characteristics of Beidou micro base stations according to claim 1, characterized in that, In the fourth step, peak detection begins when the Doppler difference exceeds the threshold. The Doppler difference at the current moment is judged in real time. If the current value is greater than the value at the previous moment, the maximum feature value is updated to the current value. If the current value is less than the value at the previous moment, the value at the previous moment is the maximum feature value. This yields the positions of the four lattice centers.

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