Fusion positioning method based on Beidou pseudolite

Abstract

The invention discloses a fusion positioning method based on a Beidou pseudo satellite, and aims to solve the problem of one-dimensional positioning in shielding environments such as indoor galleries, underground pipe galleries and railway tunnels, and adopts a positioning method integrating pseudo satellites and inertial navigation. Firstly, a positioning area is divided into a plurality of linear positioning sub-areas, pseudo satellites are erected at the two ends of each sub-area, carrier phases and pseudo-range values are measured through a receiver, pseudo-range difference values between the pseudo satellites are corrected through the carrier phases, pseudo-range difference positioning is carried out, and positioning points of the receiver at the previous moment and the current moment are calculated; the distance between the positioning points is compared with the inertial navigation recursive distance, the optimal correction value of the pseudo-range is found in the fluctuation range of the pseudo-range error, and the pseudo-range differential positioning result corresponding to the optimal correction value is the final positioning result.

Description

Technical Field

[0001] The present invention relates to the field of safety monitoring of personnel and vehicles and intelligent transportation in shielded environments such as indoor corridors, underground pipe galleries and railway tunnels, and in particular to a fusion positioning method based on Beidou pseudo-satellite. Background Art

[0002] With the maturity of various indoor positioning technologies, people begin to hope to apply relevant indoor positioning technologies to narrow and long sheltered environments such as railway tunnels, highway tunnels, and underground pipe galleries to achieve positioning, monitoring and management of personnel and vehicles. At present, the mainstream indoor positioning technologies mainly include Bluetooth positioning, WIFI positioning, ultra-wideband positioning and other technologies. Although they have solved certain indoor positioning problems, they still have certain limitations. First of all, the positioning accuracy of Bluetooth and WIFI positioning technologies is limited, and the cost of ultra-wideband is high and the coverage is limited.

[0003] At present, high-precision positioning of pedestrians can be achieved in outdoor environments through the Beidou navigation and positioning system. Pseudo-satellites use the same positioning technology to broadcast Beidou-like navigation signals in shielded environments such as indoors and underground, and use receivers to measure the distance between users and pseudo-satellites to achieve positioning. In addition, pseudo-satellites have a wide signal coverage range, which can reduce the deployment of equipment. For narrow and long environments such as tunnels and pipe corridors, directional antennas can be used to radiate pseudo-satellite signals along the direction of the tunnel, reduce the reflection of the signal by the tunnel wall, and improve the ranging accuracy. Therefore, a fusion positioning method based on Beidou pseudo-satellites is proposed to solve the one-dimensional positioning problem in shielded environments such as underground pipe corridors and railway tunnels. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a Beidou pseudo-satellite fusion positioning method, which adopts the pseudo-satellite + inertial navigation fusion positioning method to solve the one-dimensional positioning problem in narrow and long shielded environments such as tunnels, pipe corridors, and corridors, and realize the positioning control of personnel and vehicles in tunnels, pipe corridors, and corridors.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A fusion positioning method based on Beidou pseudo-satellite comprises the following steps:

[0007] (1) The positioning area is divided into a plurality of linear positioning sub-areas, and two pseudolites are respectively set up at the two ends of the positioning sub-areas, which are set as pseudolites 1 and pseudolites 2. Pseudolites 1 and 2 transmit navigation signals respectively, and the navigation signal power is adjusted so that the navigation signal covers the entire positioning sub-area, and the coordinates of the pseudolites are calibrated by a total station;

[0008] (2) Fix the receiver at a known point to receive navigation signals and measure the pseudoranges of the pseudo-satellites at both ends. Eliminate the clock error between the pseudo-satellite and the receiver by using the pseudorange difference. Then, use the actual distance difference from the known point to the two pseudo-satellite transmitting antennas to calculate the clock error between the pseudo-satellites and compensate for the pseudorange difference.

[0009] (3) Assembling the receiver and the inertial navigation system on the same carrier. When the carrier is not moving, the initial coordinates of the carrier are calculated using the pseudo-range difference after compensation between pseudo-satellites. The motion trajectory of the carrier is on the line connecting the ground projections of the pseudo-satellites at both ends.

[0010] (4) After the carrier moves, the inertial navigation is used to calculate the distance the carrier has moved at the current moment relative to the previous moment. At the same time, within the pseudo-range measurement error range, the carrier phase measured by the receiver is used to correct the compensated pseudo-range difference;

[0011] (5) Based on the corrected pseudo-range difference, the coordinate point of the carrier is calculated, the distance between the two coordinate points at the previous moment and the current moment is obtained, and the distance difference with the inertial navigation is calculated. When the difference is the smallest, the two calculated coordinate points are the positions of the carrier at the two moments.

[0012] Furthermore, step (2) specifically includes the following steps:

[0013] (201) The receiver is fixed at a known point to receive the navigation signal, and the pseudorange observations ρ1 and ρ2 from the receiver to pseudolite 1 and pseudolite 2 are obtained, and the difference is processed as follows:

[0014] Δρ 2,1 =ρ2-ρ1 (1)

[0015] Based on the pseudorange observation equation, formula (1) can be further written as:

[0016]

[0017] Where: Δρ 2,1 is the pseudo-range difference from the receiver to the transmitting antennas at both ends; and is the real distance from the receiver to pseudo-satellite 1 and pseudo-satellite 2; δt u is the clock deviation between the receiver and GPS; δt 2 and δt 1 are the clock deviations between pseudo-satellite 2 and pseudo-satellite 1 and GPS respectively; c is the speed of light, ε ρ is other error;

[0018] From formula (2), we can see that when the two pseudo-range observations are subtracted, the clock bias between the receiver and GPS and other errors can be eliminated, leaving only the clock bias between pseudo-satellites (δt 2 -δt1 );

[0019] (202) According to the known point coordinates A(X a ,Y a ,Z a ), calculate the actual distance from the receiver to pseudo-satellite 1 and pseudo-satellite 2, where the coordinates of pseudo-satellite 1 (X1, Y1, Z1) and pseudo-satellite 2 (X2, Y2, Z2) have been calibrated in step (1), so the formula (2) for:

[0020]

[0021] (203) According to formula (2) and formula (3), the compensation value ρ of the pseudo-range difference between pseudo-satellites is calculated: c =ΔL-Δρ 2,1 .

[0022] Furthermore, the specific process of calculating the initial coordinates of the carrier in step (3) is as follows:

[0023] The line connecting the ground projections of the two pseudolites at both ends is taken as the X-axis and the vertical line is taken as the Y-axis to establish a coordinate system; the Y-axis coordinates of pseudolites 1, 2 and the carrier are the same. The coordinates of the carrier at the initial moment are assumed to be (x0, y0, z0), where the height z0 is a fixed value H. The calculation formula of the carrier coordinates is as follows:

[0024]

[0025] in, is the pseudorange difference between pseudo-satellite 2 and pseudo-satellite 1 at the initial moment. By solving the above formula, x0 is obtained, and the coordinates of the carrier at the initial moment are obtained.

[0026] Furthermore, the specific steps of step (4) are as follows:

[0027] (401) After the carrier moves, the moving distance of the carrier at the current time i compared to the time i-1 is calculated based on the motion state of the carrier at the previous time i-1 by using the inertial navigation one-dimensional track recursion.

[0028] Among them, S is the distance moved by the carrier, a is the acceleration of the carrier, and υ0 is the speed of the carrier at time i-1;

[0029] (402) According to the tracking accuracy of the receiver for the C / A code phase, the pseudo-range difference between pseudo-satellites is not greater than the set threshold value A. At the same time, the carrier phase measurement accuracy is much greater than the pseudo-range measurement accuracy. Therefore, the compensated pseudo-range difference is corrected using the carrier phase measured by the receiver. The calculation formula is as follows:

[0030]

[0031] Among them, N i is the integer cycle of the carrier phase at time i, λ is the wavelength of the navigation signal, is the pseudorange difference between pseudolite 2 and pseudolite 1 at time i, is the fractional part of the carrier phase difference between pseudolite 2 and pseudolite 1 at time i;

[0032] (403) According to the formula Calculate N i All values ​​of n i , and then obtain the corresponding corrected pseudorange difference

[0033] Furthermore, the specific steps of step (5) are as follows:

[0034] (501) According to the formula Calculate the coordinate point P at time i-1 and i i-1 and P i ;

[0035] (52) Let ΔP = ||P i -P i-1 ||, among all the values ​​of ΔP, when the value of |ΔP-S| is the smallest, the coordinates obtained at time i are the position of the current carrier.

[0036] The advantages of the present invention compared with the prior art are:

[0037] The mainstream technologies for positioning personnel and vehicles in narrow and long shielded environments include Bluetooth positioning technology and ultra-wideband positioning technology. However, since Bluetooth positioning technology mostly uses fingerprint positioning or RSSI technology, the workload of fingerprint collection in the early stage of fingerprint positioning is large, and the fingerprint will change due to environmental influences, and the positioning is unstable. The positioning accuracy of RSSI technology is often only about 2m, and the technology in the present invention can achieve higher-precision positioning by using the fusion of pseudo-satellite and inertial navigation. For ultra-wideband positioning technology, two-way ranging is used for transmitting and receiving. Although it can achieve high-precision positioning, it cannot locate high-speed targets, and pseudo-satellite positioning uses passive positioning, which is not limited by high-speed targets and can still achieve positioning. On the whole, the method of pseudo-satellite plus inertial navigation fusion can achieve high-precision location services while meeting the positioning of personnel and vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a principle block diagram of the present invention.

[0039] Figure 2 It is a flow chart of the present invention. DETAILED DESCRIPTION

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

[0041] like Figure 1 and Figure 2 As shown, a fusion positioning method based on Beidou pseudo-satellite includes the following steps:

[0042] (1) The positioning area is divided into a plurality of linear positioning sub-areas. Pseudolite 1 and pseudolite 2 are respectively set up at both ends of the positioning sub-areas to transmit navigation signals. The navigation signal power is adjusted so that the pseudolite navigation signal can cover the entire positioning sub-area. The coordinates of the pseudolite are calibrated by a total station, and the coordinates (X1, Y1, Z1) and (X2, Y2, Z2) of pseudolite 1 and pseudolite 2 are recorded for subsequent receiver positioning.

[0043] (2) The receiver is fixed on a known point A, receives the pseudo-satellite navigation signal, and measures the pseudo-range to the pseudo-satellites at both ends. Due to the existence of the pseudo-satellite clock error and the clock error between the pseudo-satellite and the receiver, the measured pseudo-range contains errors. The clock error between the pseudo-satellite and the receiver is eliminated by pseudo-range difference. The actual distance difference from the known point to the two transmitting antennas is used to further calculate the clock error between the pseudo-satellites, which is used to compensate for the difference between the pseudo-ranges in the subsequent positioning process.

[0044] The specific steps are as follows:

[0045] (201) The receiver is fixed at a known point to receive the navigation signal, and the pseudorange observations ρ1 and ρ2 from the receiver to pseudolite 1 and pseudolite 2 are obtained, and the difference is processed as follows:

[0046] Δρ 2,1 =ρ2-ρ1 (1)

[0047] Based on the pseudorange observation equation, formula (1) can be further written as:

[0048]

[0049] Where: Δρ 2,1 is the pseudo-range difference from the receiver to the transmitting antennas at both ends; and is the real distance from the receiver to pseudo-satellite 1 and pseudo-satellite 2; δt u is the clock deviation between the receiver and GPS; δt 2 and δt 1 are the clock deviations between pseudo-satellite 2 and pseudo-satellite 1 and GPS respectively; c is the speed of light, ε ρ is other error;

[0050] From formula (2), we can see that when the two pseudo-range observations are subtracted, the clock bias between the receiver and GPS and other errors can be eliminated, leaving only the clock bias between pseudo-satellites (δt 2 -δt 1);

[0051] (202) According to the known point coordinates A(X a ,Y a ,Z a ), calculate the actual distance from the receiver to pseudo-satellite 1 and pseudo-satellite 2, where the coordinates of pseudo-satellite 1 (X1, Y1, Z1) and pseudo-satellite 2 (X2, Y2, Z2) have been calibrated in step (1), so the formula (2) for:

[0052]

[0053] (203) According to formula (2) and formula (3), the compensation value ρ of the pseudo-range difference between pseudo-satellites is calculated: c =ΔL-Δρ 2,1 , that is, the error of the pseudorange difference caused by the clock difference between pseudosatellites.

[0054] (3) The receiver and the inertial navigation system are assembled on the same carrier. When the carrier is not moving, the initial coordinates of the carrier are calculated using the pseudo-range differences between the pseudo-satellites (after compensation). The motion trajectory points of the carrier are considered to be on the line connecting the ground projections of the pseudo-satellites at both ends.

[0055] The specific process of calculating the initial coordinates of the carrier is as follows:

[0056] The line connecting the ground projections of the two pseudo-satellites at both ends is taken as the X-axis, and its perpendicular line is taken as the Y-axis to establish a coordinate system; the Y-axis coordinates of pseudo-satellite 1, pseudo-satellite 2 and the carrier are the same. Assume that the coordinates of the carrier at the initial moment are (x0, y0, z0), where the height z0 is a fixed value H. The calculation formula of the carrier coordinates is as follows:

[0057]

[0058] in, is the pseudorange difference between pseudo-satellite 2 and pseudo-satellite 1 at the initial moment. By solving x0, the coordinates of the carrier at the initial moment can be obtained.

[0059] (4) After the carrier moves, the inertial navigation is used to calculate the distance the carrier has moved at the current moment relative to the previous moment. At the same time, within the pseudo-range measurement error range, the carrier phase measured by the receiver is used to correct the compensated pseudo-range difference.

[0060] The specific steps are as follows:

[0061] (401) After the carrier moves, the moving distance of the carrier at the current time i compared to the time i-1 is calculated based on the motion state of the carrier at the previous time i-1 by using the inertial navigation one-dimensional track recursion.

[0062] Among them, S is the distance moved by the carrier, a is the acceleration of the carrier, and υ0 is the velocity of the carrier at time i-1.

[0063] (402) According to the tracking accuracy of the receiver for the C / A code phase, the measurement error of the pseudorange is about 0.3m, so the measurement error of the pseudorange difference between pseudosatellites is about 0.6m, and the measurement accuracy of the carrier phase is about 1mm. The calculation formula for correcting the pseudorange difference by the carrier phase is as follows:

[0064]

[0065] Among them, N i is the integer cycle of the carrier phase at time i, λ is the wavelength of the pseudo-satellite navigation signal, is the pseudorange difference between pseudolite 2 and pseudolite 1 at time i, is the fractional part of the carrier phase difference between pseudolite 2 and pseudolite 1 at time i.

[0066] (403) According to the formula Calculate N i All values ​​of n i , and then obtain the corresponding corrected pseudorange

[0067] (5) Based on the corrected pseudo-range difference, the coordinate point of the carrier is calculated, and then the distance between the two coordinate points at the current moment and the previous moment is obtained. The difference between the distance calculated by inertial navigation is calculated. When the difference is the smallest, the two calculated coordinate points are the positions of the carrier at the two moments.

[0068] The specific steps are as follows:

[0069] (501) According to the formula Calculate the coordinate point P at time i-1 and i i-1 and P i .

[0070] (502) Let ΔP = ||P i -P i-1 ||, among all the values ​​of ΔP, when the value of |ΔP-S| is the smallest, the coordinates obtained at time i are the position of the current carrier.

Claims

1. A fusion positioning method based on Beidou pseudo-satellite, characterized in that: The steps include: (1) The positioning area is divided into a plurality of linear positioning sub-areas, and two pseudolites are respectively set up at the two ends of the positioning sub-areas, which are set as pseudolites 1 and pseudolites 2. Pseudolites 1 and 2 transmit navigation signals respectively, and the navigation signal power is adjusted so that the navigation signal covers the entire positioning sub-area, and the coordinates of the pseudolites are calibrated by a total station; (2) Fix the receiver at a known point to receive navigation signals and measure the pseudoranges of the pseudo-satellites at both ends. Eliminate the clock error between the pseudo-satellite and the receiver by using the pseudorange difference. Then, use the actual distance difference from the known point to the two pseudo-satellite transmitting antennas to calculate the clock error between the pseudo-satellites and compensate for the pseudorange difference. (3) Assembling the receiver and the inertial navigation system on the same carrier. When the carrier is not moving, the initial coordinates of the carrier are calculated using the pseudo-range difference after compensation between pseudo-satellites. The motion trajectory of the carrier is on the line connecting the ground projections of the pseudo-satellites at both ends. (4) After the carrier moves, the inertial navigation is used to calculate the distance the carrier has moved at the current moment relative to the previous moment. At the same time, within the pseudo-range measurement error range, the carrier phase measured by the receiver is used to correct the compensated pseudo-range difference; (5) Based on the corrected pseudo-range difference, the coordinate point of the carrier is calculated, the distance between the two coordinate points at the previous moment and the current moment is obtained, and the distance difference with the inertial navigation is calculated. When the difference is the smallest, the two calculated coordinate points are the positions of the carrier at the two moments.

2. The method for fusion positioning based on Beidou pseudo-satellite according to claim 1, characterized in that: Step (2) specifically includes the following steps: (201) The receiver is fixed at a known point to receive the navigation signal, and the pseudorange observations ρ1 and ρ2 from the receiver to pseudolite 1 and pseudolite 2 are obtained, and the difference is processed as follows: Dr. 2,1 =ρ2-ρ1 (1) Based on the pseudorange observation equation, formula (1) can be further written as: Where: Δρ 2,1 is the pseudo-range difference from the receiver to the transmitting antennas at both ends; and is the real distance from the receiver to pseudo-satellite 1 and pseudo-satellite 2; δt u is the clock deviation between the receiver and GPS; δt 2 and δt 1 are the clock deviations between pseudo-satellite 2 and pseudo-satellite 1 and GPS respectively; c is the speed of light, ε ρ is other error; From formula (2), we can see that when the two pseudo-range observations are subtracted, the clock bias between the receiver and GPS and other errors can be eliminated, leaving only the clock bias between pseudo-satellites (δt 2 -δt 1 ); (202) According to the known point coordinates A(X a ,Y a ,Z a ), calculate the actual distance from the receiver to pseudo-satellite 1 and pseudo-satellite 2, where the coordinates of pseudo-satellite 1 (X1, Y1, Z1) and pseudo-satellite 2 (X2, Y2, Z2) have been calibrated in step (1), so the formula (2) for: (203) According to formula (2) and formula (3), the compensation value ρ of the pseudo-range difference between pseudo-satellites is calculated: c =ΔL-Δρ 2,1 .

3. The method for fusion positioning based on Beidou pseudo-satellite according to claim 2, characterized in that: The specific process of calculating the initial coordinates of the carrier in step (3) is as follows: The line connecting the ground projections of the two pseudolites at both ends is taken as the X-axis and the vertical line is taken as the Y-axis to establish a coordinate system; the Y-axis coordinates of pseudolites 1, 2 and the carrier are the same. The coordinates of the carrier at the initial moment are assumed to be (x0, y0, z0), where the height z0 is a fixed value H. The calculation formula of the carrier coordinates is as follows: in, is the pseudorange difference between pseudo-satellite 2 and pseudo-satellite 1 at the initial moment. By solving the above formula, x0 is obtained, and the coordinates of the carrier at the initial moment are obtained.

4. The method for fusion positioning based on Beidou pseudo-satellite according to claim 3, characterized in that: The specific steps of step (4) are as follows: (401) After the carrier moves, the moving distance of the carrier at the current time i compared to the time i-1 is calculated based on the motion state of the carrier at the previous time i-1 by using the inertial navigation one-dimensional track recursion. Among them, S is the distance moved by the carrier, a is the acceleration of the carrier, and υ0 is the speed of the carrier at time i-1; (402) According to the tracking accuracy of the receiver for the C / A code phase, the pseudo-range difference between pseudo-satellites is not greater than the set threshold value A. At the same time, the carrier phase measurement accuracy is much greater than the pseudo-range measurement accuracy. Therefore, the compensated pseudo-range difference is corrected using the carrier phase measured by the receiver. The calculation formula is as follows: Among them, N i is the integer cycle of the carrier phase at time i, λ is the wavelength of the navigation signal, is the pseudorange difference between pseudolite 2 and pseudolite 1 at time i, is the fractional part of the carrier phase difference between pseudolite 2 and pseudolite 1 at time i; (403) According to the formula Calculate N i All values ​​of n i , and then obtain the corresponding corrected pseudorange difference 5. The method for fusion positioning based on Beidou pseudo-satellite according to claim 4, characterized in that: The specific steps of step (5) are as follows: (501) According to the formula Calculate the coordinate point P at time i-1 and i i-1 and P i ; (52) Let ΔP = ||P i -P i-1 ||, among all the values ​​of ΔP, when the value of |ΔP-S| is the smallest, the coordinates obtained at time i are the position of the current carrier.

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