Beidou micro base station self-closed loop long and narrow space positioning method based on asynchronous network

Abstract

The application relates to the field of indoor navigation and discloses a Beidou micro base station self-closed loop long and narrow space positioning method based on an asynchronous network. A current receiving terminal works in a mode of first capturing and tracking a Beidou micro base station signal, and only after the tracking is stable, ranging information is output. However, due to the complex diversity of indoor space, the receiving terminal is affected by 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 a conventional navigation algorithm, and it is more difficult to realize the fixing of integer ambiguity, so that the receiver is difficult to realize positioning in the environment. The application only needs to ensure rough GNSS timing or network timing. On this basis, through fully mining of a Doppler characteristic parameter of the Beidou micro base station, absolute and relative fusion continuous positioning in a long and narrow space can be realized, the acquisition of a precise calibration point position is effectively realized, and the positioning continuity and positioning precision of the terminal are improved.

Description

Technical Field

[0001] The present invention relates to the field of indoor navigation, and is mainly aimed at the problem of Beidou micro base station positioning in narrow and long spaces indoors and underground. Background Art

[0002] In recent years, with the development of Beidou satellite navigation technology, the demand for vehicle positioning in shielded areas such as highway tunnels, railway tunnels, underground pipeline corridors, and subways has become increasingly strong. Currently, research on positioning in narrow and long spaces based on GNSS navigation signals is relatively limited. In response to the need for train positioning in high-speed tunnels, Jiang Yun, Zhang Wenyu, and others proposed a Beidou signal regeneration and extension system connected to an optical fiber tunnel. They verified the positioning and timing requirements of trains at up and down speeds in the tunnel, but did not provide specific quantitative performance metrics. Song Maozhong's team at Nanjing University of Aeronautics and Astronautics proposed a tunnel environment relay positioning method using simulated source pseudolites. By establishing a signal propagation model, navigation signals from low-elevation satellites located in the tunnel extension direction are simulated at both ends of the tunnel. After transmission, these signals are received and resolved within the tunnel to achieve positioning. Furthermore, a signal delay control method is used to pre-compensate for pseudorange errors. This system requires only the installation of a leaky cable or antenna in the tunnel to transmit navigation signals, achieving real-time one-dimensional positioning in straight tunnels. It is compatible with existing standard GPS receivers and can achieve centimeter-level accuracy in laboratory corridor simulations. However, this method fails to incorporate the actual tunnel environment, and the experimental process lacks consideration of factors such as error correction in ranging information and the influence of vehicle motion. Zhang Yonghu proposed a system and method for continuous positioning using navigation signals inside and outside tunnels. This system primarily consists of a radar speed and range finder, a timing receiver, an alternately connected satellite navigation signal simulator and leaky cable, and an integrated control subsystem. Wang Xuanxi et al. developed a method for tunnel positioning based on pseudolites. This method adjusts the Doppler frequency of the pseudolites' carrier wave, enabling rapid and accurate position fingerprint changes. This method forms a tunnel fingerprint and provides a solution for tunnel positioning. However, in narrow and long indoor environments like tunnels, pseudolites impose limitations on antenna layout, resulting in high fingerprint construction costs and environmental influences. Based on the aforementioned research status, although the physical characteristics of narrow and long spaces are relatively simple, spatial constraints hinder the ability of pseudolites to provide continuous positioning services in these spaces. Currently, a stable solution for narrow and long space positioning has not yet been developed. This paper focuses on how to implement Beidou pseudolites for narrow and long space positioning and proposes a Beidou micro-base station self-closed-loop narrow and long space positioning method based on an asynchronous network. Summary of the Invention

[0003] To address this issue, this paper proposes a closed-loop positioning method for Beidou micro base stations in narrow and long spaces based on an asynchronous network. This simple and efficient method not only circumvents the current challenges faced by Beidou micro base stations in narrow and long spaces, but also eliminates the need for a strictly synchronized network, providing continuous positioning results.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A Beidou micro base station self-closed loop narrow space positioning method based on an asynchronous network, characterized by specifically including the following processes:

[0006] Step 1: Multiple beacon-type Beidou micro base stations are deployed sequentially in a narrow and long space environment. After each Beidou micro base station synchronizes its own time with the GNSS system through its own timing receiver, it broadcasts the Beidou micro base station signal to the coverage area.

[0007] Step 2: The user receiver obtains the Doppler value of the Beidou micro base station in real time. When the Doppler value in the vertical direction of the movement speed is 0 and the first-order Doppler value shows an extreme value characteristic, the user receiver's position is obtained when the user receiver moves directly under the Beidou micro base station antenna based on the correspondence between the position point and the first-order Doppler value.

[0008] Step 3: Use the current position as the initial point and obtain the dynamic position of the user receiver in real time based on the relative relationship between position and speed.

[0009] Furthermore, the corresponding relationship between the position point and the Doppler first-order quantity in the second step is:

[0010]

[0011] Where v is the velocity, x is the position coordinate in the radial direction between arrays, h is the height of the array antenna, λ is the wavelength of the signal, and f is the wavelength of the signal. d ′ is the first-order Doppler quantity.

[0012] Furthermore, in the second step, the Doppler value 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 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 extreme value. The moment when the user receiver moves to directly below the Beidou micro base station antenna is thus obtained.

[0013] Furthermore, in the second step, the actual Doppler value generated by the clock drift at the current position is obtained as:

[0014] DOP=[dp1 dp2...dp n ]

[0015] dp i =Δf i +dopi

[0016] Where DOP is the Doppler value of n Beidou micro base station signals measured in real time, Δf i is the clock difference between the BeiDou micro base station and the user receiver, dop i is the Doppler value generated by the velocity, dp i is the actual Doppler value, i is the i-th Beidou micro base station signal;

[0017] When the user receiver moves at a speed perpendicular to the antenna, the Doppler generated by the speed is 0. The Doppler value at this time is the same as when the user receiver is static, which is the Doppler value generated by the clock drift. Therefore, the clock drift Doppler value of the n-channel signal is:

[0018]

[0019] Where n is the number of Beidou micro base stations.

[0020] Furthermore, when the user receiver moves to the position directly below the Beidou micro base station antenna, the position of the user receiver is obtained, which specifically includes the following process:

[0021] First, the current position vector of the Beidou micro base station is:

[0022]

[0023] Where, e is the unit vector between the current position and each transmitting antenna, [xyz] is the current position coordinate of the user receiver, [x n y n z n ] is the position coordinate of the nth transmitting antenna of the Beidou micro base station.

[0024] Then the velocity vector relationship at the current moment is

[0025] V=[v1 v2...v n ]

[0026] =ve T

[0027] v n is the velocity relative to the nth transmitting antenna position of the BeiDou micro base station, v n =[v n,x v n,y v n,z ], v is the speed of the user receiver;

[0028] The relationship between velocity and Doppler is:

[0029]

[0030] Wherein, λ is the wavelength of Beidou micro base station signal;

[0031] Then, using the above formula, we can get the relationship between the speed and position at the current moment:

[0032]

[0033] From this we can see that the relationship between Doppler and position is:

[0034]

[0035] The current position of the user receiver is obtained from this.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] The method leverages the lack of ambiguity and excellent stability of Beidou micro-base station Doppler values. By extracting the absolute Doppler value and first-order Doppler variation characteristics of a single array of Beidou micro-base stations, it accurately locates the receiver in narrow and long spaces. By leveraging the relationship between Doppler motion characteristics and position and velocity, it achieves continuous positioning of Beidou micro-base stations in narrow and long spaces using a single parameter characteristic. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a diagram of the deployment scenario of the Beidou micro base station narrow space system of the present invention.

[0039] Figure 2 This is a relationship diagram between the characteristic parameters and location of the Beidou micro base station of the present invention. DETAILED DESCRIPTION

[0040] The present invention will be further explained below with reference to the accompanying drawings.

[0041] A Beidou micro base station self-closed-loop narrow space positioning method based on an asynchronous network specifically includes the following processes:

[0042] Step 1: Deploy multiple array beacon-type Beidou micro base stations in sequence in a narrow and long space environment. The deployment scenario is as follows: Figure 1 As shown in the figure, each Beidou micro base station synchronizes its own time with the GNSS system through its own timing receiver and then broadcasts the Beidou micro base station signal to the coverage space;

[0043] Step 2: The user receiver obtains the Doppler data at the current moment in real time. Figure 2The relationship diagram shows the current Doppler value and the difference between the previous and next moments in real time. If the current Doppler difference is greater than the previous value, the extreme value is updated to the current value. If the current value is less than the previous value, the previous value is considered the extreme value. When the Doppler difference exhibits extreme characteristics and the Doppler value approaches 0, the time at which the user receiver moves directly below the Beidou micro base station antenna is determined.

[0044] Normally, due to the time-frequency difference between the BeiDou micro base station and the receiver, the actual Doppler information we obtain is

[0045] DOP=[dp1 dp2...dp n ]

[0046] dp i =Δf i +dop i

[0047] Where DOP is the Doppler value of n Beidou micro base station signals measured in real time, Δf i is the clock difference between the BeiDou micro base station and the user receiver, dop i is the Doppler value generated by the velocity, dp i is the actual Doppler value, i is the i-th Beidou micro base station signal;

[0048] When the receiver's moving speed is perpendicular to the antenna, the Doppler generated by the speed is 0. The Doppler value at this time is the same as when the receiver is static, which is the Doppler value generated by the clock drift. Therefore, the clock drift Doppler value of the n-channel signal is

[0049]

[0050] Where n is the number of Beidou micro base stations.

[0051] Assuming that the position under the antenna array obtained by the above process is s0 = [x0 y0 z0], the relationship between the current speed and position can be obtained from the above process:

[0052]

[0053] V=[v1 v2...v n ]

[0054] =ve T

[0055] Where, e is the unit vector between the current position and each transmitting antenna, [xyz] is the current position coordinate of the user receiver, [x n y n z n] is the position coordinate of the nth transmitting antenna of Beidou micro base station, v n is the velocity relative to the nth transmitting antenna position of the BeiDou micro base station, v n =[v n,x v n,y v n,z ], v is the speed of the user receiver;

[0056] The relationship between velocity and Doppler is

[0057]

[0058] Where, DOP=[dop1 dop2...dop n ] is the Doppler value of n Beidou micro base station signals measured in real time, and λ is the wavelength of the Beidou micro base station signal;

[0059] From the above formula, if the speed value at this moment is known, the position value at the current moment can be obtained using the above formula.

[0060]

[0061] From this we can see that the relationship between Doppler and position is:

[0062]

[0063] The current position of the user receiver is obtained from this.

[0064] Step 3: Use the current position as the initial point and obtain the dynamic position of the user receiver in real time based on the relative relationship between position and speed.

[0065] The above is only a specific example of the present invention, but the protection scope of the present invention is not limited thereto. Within the technical scope disclosed by the present invention, any changes that can be understood and thought of should be included in the scope of the present invention.

Claims

1. A Beidou micro base station self-closed loop narrow space positioning method based on asynchronous network, characterized in that: The specific process includes the following: Step 1: Multiple beacon-type Beidou micro base stations are deployed sequentially in a narrow and long space environment. After each Beidou micro base station synchronizes its own time with the GNSS system through its own timing receiver, it broadcasts the Beidou micro base station signal to the coverage area. Step 2: The user receiver obtains the Doppler value of the Beidou micro base station in real time. When the Doppler value in the vertical direction of the movement speed is 0 and the first-order Doppler value shows an extreme value characteristic, the user receiver's position is obtained when the user receiver moves directly under the Beidou micro base station antenna based on the correspondence between the position point and the first-order Doppler value. Step 3: Use the current position as the initial point and obtain the dynamic position of the user receiver in real time based on the relative relationship between position and speed; Among them, the corresponding relationship between the position point and the Doppler first-order quantity in the second step is: Where v is the velocity, x is the position coordinate in the radial direction between arrays, h is the height of the array antenna, λ is the wavelength of the signal, and f is the wavelength of the signal. d ′ is the first-order Doppler quantity.

2. The method for self-closed-loop narrow space positioning of Beidou micro base stations based on asynchronous network according to claim 1, characterized in that: In the second step, the Doppler value at the current moment and the Doppler difference between the previous and next moments are determined in real time. If the current Doppler difference is greater than the previous moment value, the extreme value is updated to the current value. If the current Doppler difference is less than the previous moment value, the previous moment value is the extreme value. This yields the moment when the user receiver moves to the point directly below the Beidou micro base station antenna.

3. The method for Beidou micro base station self-closed loop narrow space positioning based on asynchronous network according to claim 1, characterized in that: In the second step, the actual Doppler value generated by the clock drift at the current position is obtained: DOP=[dp1 dp2...dp n ] dp i =Δf i +dop i Where DOP is the Doppler value of n Beidou micro base station signals measured in real time, Δf i is the clock difference between the BeiDou micro base station and the user receiver, dop i is the Doppler value generated by the velocity, dp i is the actual Doppler value, i is the i-th Beidou micro base station signal; When the user receiver moves at a speed perpendicular to the antenna, the Doppler generated by the speed is 0. The Doppler value at this time is the same as when the user receiver is static, which is the Doppler value generated by the clock drift. Therefore, the clock drift Doppler value of the n-channel signal is: Where n is the number of Beidou micro base stations.

4. The method for self-closed-loop narrow space positioning of Beidou micro base stations based on asynchronous network according to claim 3 is characterized in that: In the second step, the position of the user receiver is obtained when the user receiver moves to the bottom of the Beidou micro base station antenna. The specific process includes the following: First, the current position vector of the Beidou micro base station is: Where, e is the unit vector between the current position and each transmitting antenna, [xyz] is the current position coordinate of the user receiver, [x n y n z n ] is the position coordinate of the nth transmitting antenna of the Beidou micro base station; Then the velocity vector relationship at the current moment is V=[v1 v2 ... v n ] =ve T v n is the velocity relative to the nth transmitting antenna position of the BeiDou micro base station, v n =[v n,x v n,y v n,z ], v is the speed of the user receiver; The relationship between velocity and Doppler is: Wherein, λ is the wavelength of Beidou micro base station signal; Then, using the above formula, we can get the relationship between the speed and position at the current moment: From this we can see that the relationship between Doppler and position is: The current position of the user receiver is obtained from this.

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