A method for generating VRS correction numbers based on adaptive grid points

Abstract

The present invention discloses a method for generating VRS correction numbers of adaptive grid points, which comprises the following steps: calculating the coordinates of atmospheric grid points through a real-time regional atmospheric delay model and an atmospheric error threshold, and then interpolating the atmospheric grid point coordinates to generate single-difference ionospheric delay correction numbers and single-difference tropospheric delay correction numbers; generating geometric distance correction numbers of each grid point in sequence according to the pre-set geometric grid point coordinates; generating VRS correction numbers of each grid point according to the single-difference ionospheric delay correction number, the single-difference tropospheric delay correction number and the geometric distance correction number. This is to solve the problems of low reliability, poor positioning effect and frequent initialization faced by high-dynamic users in the existing positioning technology.

Description

Technical Field

[0001] The present invention relates to the technical field of attitude estimation, and in particular to a method for generating adaptive grid point VRS correction numbers. Background Art

[0002] The existing grid-based VRS technology has the following problems:

[0003] First, although the gridded VRS technology effectively breaks the constraint of the number of users on the network RTK technology, making it possible for the GNSS high-precision positioning service to further expand its application areas, it is also necessary to pay attention to the problem of the gridded VRS technology itself, that is, the grid division standards all rely on the operator's experience judgment or the verification of the measured results. Considering the variability and complexity of the atmospheric environment in different time and space environments, the grid division standards set based on experience actually increase the uncontrollability of the positioning effect and reduce the reliability of positioning.

[0004] Secondly, the atmospheric grid points are directly related to the current atmospheric delay. Since the atmospheric delay changes over time, the density and position of the atmospheric grid points are also changing. Combined with the above theory, the change of VRS site will cause users to re-converge fixed ambiguity. Frequent site changes will seriously reduce the user's positioning effect.

[0005] Finally, in the existing VRS correction number generation method, the ionospheric delay correction number, tropospheric delay correction number, orbit error correction number and geometric distance correction number all use the same set of virtual reference station coordinates. This results in the existing VRS technology being limited by its own technical solutions when facing highly dynamic users, and requiring frequent changes in the position of the virtual reference station to ensure the distance between the user and the user. Therefore, highly dynamic users also face frequent initialization caused by the continuous relocation of virtual reference stations when using network RTK services. Summary of the invention

[0006] In order to solve the above shortcomings and deficiencies of the prior art, an object of the present invention is to provide a method for generating adaptive grid point VRS correction numbers.

[0007] The technical solution of the present invention is: a method for generating adaptive grid point VRS correction numbers, the method comprising the following steps:

[0008] Generate a real-time atmospheric error model based on linear interpolation or inverse range interpolation through the real-time atmospheric information of each baseline of the CORS network, calculate the coordinates of the atmospheric grid points based on the real-time atmospheric error model and the atmospheric error threshold, and then generate single-difference ionospheric delay corrections and single-difference tropospheric delay corrections based on the interpolation of the atmospheric grid point coordinates;

[0009] According to the preset geometric grid point coordinates, the geometric distance correction number of each grid point is generated in sequence;

[0010] The VRS correction number for each grid point is generated based on the single-difference ionospheric delay correction number, the single-difference tropospheric delay correction number and the geometric distance correction number.

[0011] Furthermore, the method for calculating the atmospheric grid point coordinates comprises the following steps:

[0012] S01, calculate the atmospheric grid step length;

[0013] S02. Divide the atmospheric grid.

[0014] Furthermore, the calculation method of the atmospheric grid step length is as follows:

[0015] S01-1. Calculate the fitting factors of the ionospheric delay and tropospheric delay in the region on longitude and latitude;

[0016] S01-2. Calculate the division step size of the grid on longitude and latitude by using the fitting factor and the atmospheric error threshold.

[0017] Furthermore, the calculation method of the fitting factor is:

[0018]

[0019] Cor u =a1·ΔX u +a2·ΔY u ;

[0020] Where Err represents the atmospheric error of each baseline, ΔX represents the mapping length of the baseline in the longitude direction, ΔY represents the mapping length of the baseline in the latitude direction, and Cor u represents the fitting factor of the u-th baseline, a1 represents the interpolation coefficient of the ionospheric delay and tropospheric delay in the region on the longitude, a2 represents the interpolation coefficient of the ionospheric delay and tropospheric delay in the region on the latitude, n represents the maximum number of the baseline, and u represents the baseline number.

[0021] Furthermore, the calculation method of the division step length of the grid on the longitude and latitude is:

[0022] Find Δx 2 +Δy 2 Minimum value, solve Δx, Δy, η represents the atmospheric error threshold;

[0023] Where Δx represents the grid division step on the meridian, and Δy represents the grid division step on the meridian.

[0024] Furthermore, the method for generating the VRS correction number is as follows:

[0025]

[0026] Wherein, subscript VRS stands for virtual reference station, subscript MAS stands for master reference station, where the master reference station is the GNSS reference station closest to the user's approximate coordinates, subscript 1 stands for satellite L1 carrier signal, subscript 2 stands for satellite L2 carrier signal; λ is the wavelength of the carrier signal, is the carrier phase observation value, ΔN is the single difference ambiguity, P is the pseudorange observation value, is the single-difference satellite-to-ground distance correction number of the virtual reference station and the main reference station with respect to satellite i; is the single-difference L1 ionospheric delay correction of the virtual reference station and the main reference station with respect to satellite i; is the single-difference L2 ionospheric delay correction of the virtual reference station and the main reference station with respect to satellite i; is the single-difference tropospheric delay correction of the virtual reference station and the main reference station with respect to satellite i; is the residual error correction of the primary reference station with respect to satellite i; is the single difference orbit error correction number of the virtual reference station and the main reference station with respect to satellite i.

[0027] Furthermore, the density of the geometry grid points is one geometry grid point for each reference station.

[0028] The beneficial effects of the present invention are: compared with the prior art,

[0029] 1) Based on the gridded VRS technology, the present invention proposes a method for generating adaptive gridded VRS correction numbers based on satellite-station atmospheric delay information. The method analyzes the accuracy of the real-time atmospheric delay model of the CORS network and autonomously adjusts the grid division step size according to the changes in the atmospheric environment, so that the atmospheric delay error between the user's arbitrary location within the CORS service range and the correction number is less than the specified value, thereby ensuring the accuracy and reliability of the positioning service;

[0030] 2) The present invention separates the geometric grid and the atmospheric grid, and the coordinate position of the atmospheric grid changes in real time with the atmospheric information to ensure the positioning accuracy of the user;

[0031] 3) The traditional mode will reinitialize if the moving distance is too long, while the geometric grid points of the present invention are fixed in position, ensuring the continuity of the user's measurement, and the geometric grid can be set to be relatively sparse. Through the combination of two sets of grids, compared with the traditional VRS technology and the first generation of gridded VRS correction number technology that require frequent initialization, the present invention does not require initialization for long-distance movement, can ensure the user's positioning accuracy in real time, and at the same time improve the service quality for highly dynamic users. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Flow chart of Example 1 of the present invention. DETAILED DESCRIPTION

[0033] The invention is further described below in conjunction with the accompanying drawings and specific embodiments:

[0034] Implementation Example 1: Reference Figure 1 , a method for generating adaptive grid point VRS correction numbers, the method comprising the following steps:

[0035] A real-time atmospheric error model is generated based on linear interpolation or inverse distance interpolation through the real-time atmospheric information of each baseline of the CORS network, and the coordinates of the atmospheric grid points are calculated based on the real-time atmospheric error model and the atmospheric error threshold. The single-difference ionospheric delay correction number and the single-difference tropospheric delay correction number are then interpolated according to the atmospheric grid point coordinates. The geometric distance correction number of each grid point is generated in turn according to the pre-set geometric grid point coordinates; the VRS correction number of each grid point is generated according to the single-difference ionospheric delay correction number, the single-difference tropospheric delay correction number and the geometric distance correction number.

[0036] When users use VRS corrections for differential positioning, assuming that the distance-related error corrections such as tropospheric delay corrections, ionospheric delay corrections, and orbit error corrections are completely eliminated, the observation variance can be simplified to:

[0037]

[0038] Wherein, subscript VRS stands for virtual reference station, subscript rover stands for rover, VRS-rover stands for virtual station to rover, subscript 1 stands for satellite L1 carrier signal, subscript 2 stands for satellite L2 carrier signal, λ is the wavelength of carrier signal, is the carrier phase observation value, is the double difference ambiguity, Double-difference carrier phase observations, is the double-difference pseudorange observation value, and the superscripts i and j represent the satellite numbers.

[0039] As can be seen from the above formula, the geometric distance correction number and other distance-related error correction numbers are independent of each other. Therefore, the geometric distance correction number and other error correction numbers can be processed separately. Because the ionospheric delay correction number, the tropospheric delay correction number, the orbit error correction number, etc. are all distance-related error correction numbers, it is necessary to use coordinates closer to the user to generate correction numbers. However, since the geometric distance correction number is not related to any error in the observation value, it does not affect the user's final positioning accuracy, so the geometric distance correction number can actually be any value. In the traditional VRS correction number, the use of the same coordinates as the atmospheric delay correction number to calculate the geometric correction number is more to improve the authenticity of the VRS observation value, and has no effect on the positioning result. However, this calculation method restricts the positioning effect of high-dynamic users. In the present invention, the coordinates used to calculate the geometric correction number and the atmospheric error correction number are distinguished. The atmospheric error correction number uses the coordinates of the atmospheric grid point, and the coordinates required for the geometric correction number can get rid of the limitation of the distance between the user. Considering the frequent initialization of highly dynamic users, it is necessary to significantly reduce the frequency of changes in the geometric information in the VRS corrections during the user's movement, so the density of the geometric grid for calculating the geometric corrections should be reduced as much as possible. However, considering that the VRS observations are generated based on the master station observations, at least one geometric grid point needs to be set for each base station. Since the location of the geometric grid points does not affect the user's positioning results, the specific number and location of the settings can be determined by the user.

[0040] Furthermore, the method for calculating the atmospheric grid point coordinates comprises the following steps:

[0041] S01, calculate the atmospheric grid step length;

[0042] S02. Divide the atmospheric grid.

[0043] Furthermore, the calculation method of the atmospheric grid step length is as follows:

[0044] S01-1. Calculate the fitting factors of the ionospheric delay and tropospheric delay in the region on longitude and latitude;

[0045] S01-2. Calculate the division step size of the grid on longitude and latitude by using the fitting factor and the atmospheric error threshold.

[0046] Furthermore, the calculation method of the fitting factor is:

[0047]

[0048] Cor u =a1·ΔX u +a2·ΔY u ;

[0049] Where Err represents the atmospheric error of each baseline, ΔX represents the mapping length of the baseline in the longitude direction, ΔY represents the mapping length of the baseline in the latitude direction, and Cor u represents the fitting factor of the u-th baseline, a1 represents the interpolation coefficient of the ionospheric delay and tropospheric delay in the region on the longitude, a2 represents the interpolation coefficient of the ionospheric delay and tropospheric delay in the region on the latitude, n represents the maximum number of the baseline, and u represents the baseline number.

[0050] Furthermore, the calculation method of the division step length of the grid on the longitude and latitude is:

[0051] Find Δx 2 +Δy 2 Minimum value, solve Δx, Δy, η represents the atmospheric error threshold;

[0052] Where Δx represents the grid division step on the meridian, and Δy represents the grid division step on the meridian.

[0053] Furthermore, the method for generating the VRS correction number is as follows:

[0054]

[0055] Wherein, subscript VRS stands for virtual reference station, subscript MAS stands for master reference station, where the master reference station is the GNSS reference station closest to the user's approximate coordinates, subscript 1 stands for satellite L1 carrier signal, subscript 2 stands for satellite L2 carrier signal; λ is the wavelength of the carrier signal, is the carrier phase observation value, ΔN is the single difference ambiguity, P is the pseudorange observation value, is the single-difference satellite-to-ground distance correction number of the virtual reference station and the main reference station with respect to satellite i; is the single-difference L1 ionospheric delay correction of the virtual reference station and the main reference station with respect to satellite i; is the single-difference L2 ionospheric delay correction of the virtual reference station and the main reference station with respect to satellite i; is the single-difference tropospheric delay correction of the virtual reference station and the main reference station with respect to satellite i; is the residual error correction of the primary reference station with respect to satellite i; is the single difference orbit error correction number of the virtual reference station and the main reference station with respect to satellite i.

[0056] Furthermore, the density of the geometric grid points is one geometric grid point per base station.

[0057] Finally, each grid point is distinguished by the atmospheric grid point coordinates. When selecting the grid point VRS correction number based on the user's approximate coordinates, the corresponding grid point VRS is also selected based on the principle of minimizing the user coordinates and the atmospheric grid point coordinates. However, it should be noted that when broadcasting the correction number, the coordinates of the broadcast VRS observation value should be the geometric grid point coordinates.

[0058] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A method for generating adaptive grid point VRS corrections, characterized in that: The method comprises the following steps: Generate a real-time atmospheric error model based on linear interpolation or inverse range interpolation through the real-time atmospheric information of each baseline of the CORS network, calculate the coordinates of the atmospheric grid points based on the real-time atmospheric error model and the atmospheric error threshold, and then generate single-difference ionospheric delay corrections and single-difference tropospheric delay corrections based on the interpolation of the atmospheric grid point coordinates; According to the preset geometric grid point coordinates, the geometric distance correction number of each grid point is generated in sequence; Generate VRS corrections for each grid point based on single-difference ionospheric delay corrections, single-difference tropospheric delay corrections, and geometric distance corrections; The method for calculating the atmospheric grid point coordinates comprises the following steps: S01, calculate the atmospheric grid step size; S02, divide the atmospheric grid; The calculation method of the atmospheric grid step length is as follows: S01-1. Calculate the fitting factors of the ionospheric delay and tropospheric delay in the region on longitude and latitude; S01-2. Calculate the grid division step size on longitude and latitude by using the fitting factor and the atmospheric error threshold; The calculation method of the fitting factor is: Cor u =a1·ΔX u +a2·ΔY u ; Where Err represents the atmospheric error of each baseline, ΔX represents the mapping length of the baseline in the longitude direction, ΔY represents the mapping length of the baseline in the latitude direction, and Cor u represents the fitting factor of the u-th baseline, a1 represents the interpolation coefficient of the ionospheric delay and tropospheric delay in the region on the longitude, a2 represents the interpolation coefficient of the ionospheric delay and tropospheric delay in the region on the latitude, n represents the maximum number of the baseline, and u represents the baseline number; The calculation method of the division step length of the grid on the longitude and latitude is: Find Δx 2 +Δy 2 Minimum value, solve Δx, Δy, η represents the atmospheric error threshold; Where Δx represents the division step of the grid on the meridian, and Δy represents the division step of the grid on the meridian.

2. The method for generating adaptive grid point VRS corrections according to claim 1, characterized in that: The method for generating the VRS correction number is as follows: Wherein, subscript VRS stands for virtual reference station, subscript MAS stands for master reference station, where the master reference station is the GNSS reference station closest to the user's approximate coordinates, subscript 1 stands for satellite L1 carrier signal, subscript 2 stands for satellite L2 carrier signal; λ is the wavelength of the carrier signal, is the carrier phase observation value, ΔN is the single difference ambiguity, P is the pseudorange observation value, is the single-difference satellite-to-ground distance correction number of the virtual reference station and the main reference station with respect to satellite i; is the single-difference L1 ionospheric delay correction of the virtual reference station and the main reference station with respect to satellite i; is the single-difference L2 ionospheric delay correction of the virtual reference station and the main reference station with respect to satellite i; is the single-difference tropospheric delay correction of the virtual reference station and the main reference station with respect to satellite i; is the residual error correction of the primary reference station with respect to satellite i; is the single difference orbit error correction number of the virtual reference station and the main reference station with respect to satellite i.

3. The method for generating adaptive grid point VRS corrections according to claim 1, characterized in that: The density of the geometry grid points is one geometry grid point per reference station.

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