CORS network solving method, system and medium considering reference station coordinate change

Abstract

The application discloses a CORS network solving method, system and medium considering reference station coordinate change, the method comprises the following steps: constructing a baseline solving double-difference observation value model, including a double-difference pseudo-range observation equation and a phase carrier observation equation of ionosphere-free combination; constructing a single-epoch error equation, and obtaining real-time estimated coordinates of each reference station; solving single-station coordinates of each reference station through PPP precise point positioning, and comparing the single-station coordinates with the real-time estimated coordinates of the reference station to determine a reference station without movement; taking the reference station without movement as a main reference station, and positioning and solving a rover station according to real-time position information uploaded by the rover station. In the reference station baseline solving filter, the reference station coordinate information is added, the latest reference station coordinates are solved according to real-time observation data, and the rover station positioning and solving is carried out based on the latest reference station coordinates, so that the influence of long-term displacement of the reference station coordinates is eliminated, and stability and accuracy are improved.

Description

Technical Field

[0001] This invention relates to the field of CORS network technology, and specifically to a CORS network solution method, system, and medium that takes into account changes in reference station coordinates. Background Technology

[0002] CORS improves mapping speed and accuracy while reducing costs by establishing multiple GPS reference stations. Among these, the VRS (Virtual Reference Station) technology is a key algorithm in the CORS network, achieving high-precision positioning and wider coverage by establishing virtual reference stations.

[0003] like Figure 1 As shown, multiple (three or more) reference stations send their real-time observation data to the control center. Based on the precise known coordinates of each reference station, the control center calculates the double-difference ambiguity of each baseline between reference stations in real time and extracts atmospheric delay information (ionospheric delay, tropospheric delay) from each baseline. The rover (user terminal) uploads its location information (GGA) to the control center in real time. The control center establishes a virtual reference station at the rover and models the ionospheric, tropospheric, and orbital errors of this virtual reference station, generating correction information in real time. This correction information is continuously and in real time transmitted to the rover via wireless communication links (GSM / GPRS / CDMA, etc.), thereby achieving high-precision (centimeter-level) real-time positioning.

[0004] Traditional reference station baseline calculation methods involve obtaining reference station coordinates beforehand using high-precision post-processing software and inputting them into a database. The network RTK software then reads these coordinates from the database and applies them to the program during the calculation. In this baseline calculation filter, the reference station coordinates are considered known information, while the parameters to be estimated are the baseline double-difference ionosphere, double-difference troposphere, and double-difference ambiguity information. The reference station coordinates are typically updated once a year. This assumes no displacement of the reference station coordinates within that year. However, crustal tracking information reveals that in areas of active crustal plates, reference station displacement can reach 2-3 cm / year. Clearly, neglecting variations in reference station displacement will negatively impact the success rate of baseline calculation and the accuracy of the terminal's positioning results.

[0005] To this end, the Chinese invention patent CN111045065B discloses a single epoch positioning method and system based on multi-reference station data, which uses the solving data of multiple baselines to establish an atmospheric error model in the baseline network, and corrects the atmospheric parameters; requests VRS point data generated by the first grid; requests VRS point data generated by the second grid, and the second grid is adjacent to the first grid; combines the VRS point data generated by the first grid and the VRS point data generated by the second grid, and performs real-time fixed solution to solve the observation value ambiguity. This scheme increases the number of equations for solving, accurately and quickly realizes single epoch fixed ambiguity, and can realize fast and accurate positioning of the mobile user under dynamic conditions. However, this scheme defaults that the first reference station is fixed and does not move, and determines the displacement of the reference station based on the solving position of the first reference station, and the final result still cannot meet the requirement of high precision.

[0006] Therefore, it is necessary to improve the existing CORS network solving method and system, eliminate the influence of long-term displacement of the reference station coordinates on the baseline solution, and improve the stability of the baseline solution and the terminal positioning accuracy. SUMMARY

[0007] In view of the above defects, the technical problem to be solved by the present application is to provide a CORS network solving method, system and medium considering the change of reference station coordinates, to solve the problem that the stability of baseline solution and the terminal positioning accuracy are deteriorated due to the influence of the displacement of reference station coordinates on the baseline solution in the prior art.

[0008] Therefore, the present application provides a CORS network solving method considering the change of reference station coordinates, comprising the following steps:

[0009] Constructing a baseline solution double-difference observation value model between each reference station, including double-difference pseudo-range observation equations of ionosphere-free combination

[0010] double-difference phase carrier observation equations of ionosphere-free combination

[0011] Constructing a single epoch error equation, and solving the real-time estimated coordinates of each reference station according to the error value of the obtained single epoch error equation and the double-difference pseudo-range observation equation double-difference phase carrier observation equation

[0012] Solving the single station coordinates of each reference station by PPP precise point positioning, and comparing with the real-time estimated coordinates of the reference station to determine the reference station that does not move;

[0013] Taking the reference station that does not move as the main reference station, and positioning the mobile station according to the real-time position information uploaded by the mobile station. ​​

[0014] In the above method, preferably,

[0015]

[0016]

[0017] wherein ρ is the geometric distance between the station and the satellite, is the double-difference geometric distance, is the double-difference tropospheric delay, εP is the double-difference pseudorange random noise, e1 is the double-difference narrow-lane coefficient without ionosphere combination, e2 is the double-difference wide-lane coefficient without ionosphere combination, is the double-difference narrow-lane ambiguity, is the double-difference wide-lane ambiguity, εL is the double-difference phase, the geometric distance ρ between the station and the satellite is the real-time coordinate of the reference station and is taken as an estimated parameter;

[0018]

[0019] wherein x r represents the coordinate value of the X direction in the spatial rectangular coordinate system of the reference station, y r represents the coordinate value of the Y direction in the spatial rectangular coordinate system of the reference station, z r represents the coordinate value of the Z direction in the spatial rectangular coordinate system of the reference station, x s represents the coordinate value of the X direction in the spatial rectangular coordinate system of the satellite, y s represents the coordinate value of the Y direction in the spatial rectangular coordinate system of the satellite, z s represents the coordinate value of the Z direction in the spatial rectangular coordinate system of the satellite.

[0020] In the above method, preferably,

[0021] The single-epoch error equation is:

[0022] The error equation of the single satellite i is:

[0023]

[0024] wherein, is the deviation of the observation value of the satellite i from the true value, is the coordinate change amount of the satellite i.

[0025] In the above method, preferably, when the number of observation values is sufficient and there are excess observations, the error value is obtained by solving the single-epoch error equation by the least square method; and the real-time estimated coordinate of each reference station is obtained by filtering the coordinate of the reference station by using the above error value.

[0026] In the method, preferably, prior constraint information is added to the reference station coordinates during the filtering process, the prior constraint information is obtained according to historical observation data of the base station, and includes the base station coordinates and a coordinate change rate.

[0027] In the method, preferably, the single-station coordinates obtained by the PPP precise point positioning are compared with the real-time estimated coordinates of the reference stations, and the reference station with the minimum displacement is determined as the reference station without movement.

[0028] The application also provides a CORS network solving system considering the coordinate change of the reference stations, comprising:

[0029] A double-difference observation value model, comprising a double-difference pseudo-range observation equation without ionosphere combination and a double-difference phase carrier observation equation without ionosphere combination

[0030] A reference station coordinate real-time estimation module, configured to obtain real-time estimated coordinates of each reference station according to a single-epoch error equation and a double-difference pseudo-range observation equation a double-difference phase carrier observation equation

[0031] A reference station movement determination module, configured to determine single-station coordinates of each reference station by PPP precise point positioning, and compare the single-station coordinates with the real-time estimated coordinates of the reference stations to determine the reference station without movement.

[0032] A rover station positioning solving module, configured to take the reference station without movement as a main reference station, and perform positioning solving on a rover station according to real-time position information uploaded by the rover station.

[0033] In the system, preferably,

[0034]

[0035]

[0036] In the formula, ρ is a station-star geometric distance, is a double-difference geometric distance, is a double-difference tropospheric delay, εP is a double-difference pseudo-range random noise, e1 is a double-difference narrow-lane coefficient without ionosphere combination, and e2 is a double-difference wide-lane coefficient without ionosphere combination, is a double-difference narrow-lane ambiguity, is a double-difference wide-lane ambiguity, and εL is a double-difference phase, the station-star geometric distance ρ is a real-time coordinate of the reference station and serves as an estimated parameter.

[0037]

[0038] In the formula, x r ​represents the coordinate value of the X direction in the reference station space rectangular coordinate system, y r represents the coordinate value of the Y direction in the reference station space rectangular coordinate system, z r represents the coordinate value of the Z direction in the reference station space rectangular coordinate system, x s represents the coordinate value of the X direction in the satellite space rectangular coordinate system, y s represents the coordinate value of the Y direction in the satellite space rectangular coordinate system, z s represents the coordinate value of the Z direction in the satellite space rectangular coordinate system.

[0039] In the above system, preferably,

[0040] The single-epoch error equation is:

[0041] The error equation of a single star i is:

[0042]

[0043] wherein, is the deviation of the observation value of the satellite i from the true value, is the coordinate change amount of the satellite i.

[0044] The application also provides a computer readable medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the CORS network solution method considering the coordinate change of the reference station.

[0045] It can be known from the above technical solution that the CORS network solution method, system and medium considering the coordinate change of the reference station provided by the application solve the problem that the stability of baseline solution and the terminal positioning accuracy are deteriorated due to the influence of the coordinate displacement of the reference station on the baseline solution in the prior art. Compared with the prior art, the application has the following beneficial effects:

[0046] In the filter for the reference station baseline solution, instead of directly eliminating the coordinate information of the reference station as a known value, the coordinate information of the reference station is added in the reference station baseline solution filter as a filtering parameter to be estimated and solved together with other parameters, and the latest reference station coordinate is solved according to real-time observation data, so that the problem that the baseline solution and the terminal positioning result are deteriorated due to the crustal plate movement and the coordinate displacement change of the reference station can be eliminated, and the stability and accuracy of the solution are improved. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce and describe the drawings needed to be used in the description of the embodiments of the present application. Obviously, the drawings in the following description are only part of the embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0048] Figure 1 A schematic diagram for solving the VRS system;

[0049] Figure 2 A flowchart of a CORS network solving method considering the coordinate change of reference stations provided by the present application. DETAILED DESCRIPTION

[0050] The technical solutions of the embodiments of the present application will be described clearly and completely in the following with reference to the drawings of the embodiments of the present application. Obviously, the following described embodiments are only part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the scope of protection of the present application.

[0051] In order to more clearly illustrate the technical solutions and implementation modes of the present application, the following introduces several preferred specific embodiments for implementing the technical solutions of the present application.

[0052] It should be noted that the orientation words such as "inner", "outer", "front", "rear", "left" and "right" in this paper are described based on the product use state as the reference object. Obviously, the use of corresponding orientation words does not constitute a limitation on the protection scope of the present application.

[0053] Please refer to Figure 2 , Figure 2 A flowchart of a CORS network solving method considering the coordinate change of reference stations provided by the present application.

[0054] Specifically, as Figure 2 indicated, the CORS network solving method considering the coordinate change of reference stations provided by the present application comprises the following steps:

[0055] Step 110, constructing a baseline solving double-difference observation value model between each reference station, including a double-difference pseudo-range observation equation without ionosphere combination and a double-difference phase carrier observation equation without ionosphere combination

[0056]

[0057]

[0058]

[0059] wherein, ρ is station-star geometric distance, is double-difference geometric distance, is double-difference tropospheric delay, εP is double-difference pseudorange random noise, e1 is double-difference narrow-lane coefficient without ionosphere combination, e2 is double-difference wide-lane coefficient without ionosphere combination, is double-difference narrow-lane ambiguity, is double-difference wide-lane ambiguity, εL is double-difference phase random noise, station-star geometric distance ρ is real-time coordinate of reference station, which is taken as an estimated parameter in the scheme;

[0060]

[0061] wherein, x r represents coordinate value of X direction in reference station space rectangular coordinate system, y r represents coordinate value of Y direction in reference station space rectangular coordinate system, z r represents coordinate value of Z direction in reference station space rectangular coordinate system, x s represents coordinate value of X direction in satellite space rectangular coordinate system, y s represents coordinate value of Y direction in satellite space rectangular coordinate system, z s represents coordinate value of Z direction in satellite space rectangular coordinate system.

[0062] In the double-difference observation value model, real-time coordinate of the reference station is taken as an estimated parameter, which is estimated and solved together with other parameters, so that the problem of inaccurate other filtering parameters caused by coordinate change of the reference station can be eliminated.

[0063] Step 120, according to error equation error equation of single satellite i is constructed and and single epoch error equation is further constructed.

[0064] Error equation is:

[0065] Error equation of single satellite i is:

[0066] Single epoch error equation is:

[0067] wherein, represents double-difference, is error observation value; lδx is a small amount in coordinate x direction, l is the first coefficient corresponding to lδx; mδy is a small amount in coordinate y direction, m is the second coefficient corresponding to mδy; nδz is a small amount in coordinate z direction, n is the third coefficient corresponding to nδz; is the double-difference geometric distance; is the double-difference ionosphere value; is the double-difference troposphere value; is the observation value of satellite i minus the true value; mf is the troposphere mapping function, which is related to the satellite elevation angle; is the coordinate change of satellite i, and the superscript i = 1 ~ k is the satellite serial number.

[0068] Step 130, when the number of observation values is sufficient and there are excess observations, the error equation of a single epoch is solved by the least square method to obtain error values.

[0069]

[0070] Wherein, x0, y0, z0 are three direction values of prior coordinates; x r , y r , z r The three direction values of the real coordinates of the base station are obtained by solving, that is, the real-time estimated coordinates. The prior coordinates are obtained by solving the historical observation data of the base station.

[0071] Step 140, the error values are used to filter the coordinates of the corresponding reference stations to obtain the real-time estimated coordinates of each reference station.

[0072] The real-time estimated coordinates are iterated into the double-difference observation value equation to solve the baseline of each reference station, thereby improving the accuracy and stability of the output coordinates.

[0073] Further, the prior constraint information can be added to the reference station coordinates in the filtering, so that the reference station coordinate parameters and other filtering parameters are separated more quickly. The prior constraint information is obtained by solving the historical observation data of the base station, including the base station coordinates and the coordinate change rate.

[0074] Step 150, the coordinates of each reference station are solved by the PPP precise point positioning algorithm, and are compared with the real-time estimated coordinates of the reference stations obtained in step 140 to obtain the displacement of each reference station, and then the reference station which does not move is determined.

[0075] Specifically, the single station coordinates obtained by the PPP precise point positioning algorithm are compared with the real-time estimated coordinates of the reference stations, and the reference station with the minimum displacement is taken as the reference station which does not move.

[0076] Step 160, the reference station which does not move is taken as the main reference station, and the rover station (user terminal) is positioned and solved according to the real-time uploaded position information (GGA) of the rover station.

[0077] On the basis of the above method, the application further provides a CORS network solving system considering the coordinate change of the reference station, which is arranged in a control center and comprises:

[0078] Double-difference observation model, including double-difference pseudo-range observation equation without ionosphere combination and double-difference phase carrier observation equation without ionosphere combination Real-time observation data of each reference station is received, double-difference ambiguity between each reference station is solved in real time according to the double-difference observation model, and atmospheric delay information on each baseline is extracted.

[0079] Reference station coordinate real-time estimation module is used for solving single-epoch error equation and double-difference pseudo-range observation

[0080] Equation Double-difference phase carrier observation equation Real-time estimated coordinates of each reference station are obtained by solving;

[0081] Reference station movement determination module is used for solving single-station coordinates of each reference station by PPP precise point positioning, and comparing the single-station coordinates with the real-time estimated coordinates of the reference station to determine the reference station without movement;

[0082] Flow station positioning solving module is used for positioning the flow station according to the real-time uploaded position information of the flow station by taking the reference station without movement as a main reference station.

[0083] The CORS network solving method considering reference station coordinate change in the application can be realized as a computer software program. For example, the application further provides a computer readable medium, which stores a computer program, and the computer program is executed by a processor to implement the CORS network solving method considering reference station coordinate change.

[0084] According to the above specific embodiment, the CORS network solving method considering reference station coordinate change, the system and the computer readable medium provided by the application have the following advantages compared with the prior art.

[0085] First, the existing baseline solving model directly eliminates the reference station coordinates as known values, and the application increases the reference station coordinate information in the reference station baseline solving filter, so that the latest reference station coordinates can be solved according to the real-time observation data, thereby eliminating the problem of fewer fixed satellites in baseline solving caused by long-term displacement of reference station coordinates. Real-time solving of main reference station coordinates, long-period filtering, and back substitution to baseline solving make the model more robust, and the correctness of baseline solving will not decrease with the offset of reference station coordinates.

[0086] Secondly, the application solves the reference station coordinate in real time, filters by day, and does not affect the quality of VRS observation value and the measurement precision of terminal because of the decrease of the reference station coordinate accuracy, improves the stability and precision, and eliminates the problem of low terminal positioning precision caused by the deviation of the reference coordinate.

[0087] Thirdly, the reference station coordinate information is output in the baseline solution, and can be used as the coordinate reference value after long time filtering, and applied to the service operation management system to monitor the displacement change of the reference station.

[0088] Finally, it should be noted that the terms "comprising", "containing" or any other variant thereof used in this text are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement "comprising a" does not exclude the existence of other identical elements in the process, method, article or equipment including the element.

[0089] The application is not limited to the above best embodiment, and anyone should know that the structural changes made under the inspiration of the application, any technical solution with the same or similar to the application, falls within the protection scope of the application.

Claims

1. A CORS network solution method that takes into account changes in reference station coordinates, characterized in that, Includes the following steps: Construct baseline solution double-difference observation models among various reference stations, including double-difference pseudorange observation equations without ionospheric combinations. Double-difference phase carrier observation equations combined with ionosphere-free Construct a single-epoch error equation, and then use the error values ​​of the single-epoch error equation and the double-difference pseudorange observation equation obtained from the solution. Double-difference phase carrier observation equation The real-time estimated coordinates of each reference station are obtained through calculation; The coordinates of each reference station are calculated by PPP precise single-point positioning and compared with the real-time estimated coordinates of the reference stations to determine the reference stations that have not moved. Using the station that has not moved as the main reference station, the rover is positioned based on the location information uploaded by the rover in real time.

2. The method according to claim 1, characterized in that, In the formula, ρ is the geometric distance between the station and the satellite. It is a double-difference geometric distance. εp represents the double-difference tropospheric delay, εP represents the double-difference pseudorange random noise, e1 represents the double-difference narrow-lane coefficient for the ionospheric combination, and e2 represents the double-difference wide-lane coefficient for the ionospheric combination. For double-difference narrow alley ambiguity, εL represents the double-difference wide-lane ambiguity, εL represents the double-difference phase random noise, and the station-satellite geometric distance ρ represents the real-time coordinates of the reference station, which is used as the parameter to be estimated. In the formula, x r This represents the coordinate value in the X direction of the reference station in a Cartesian coordinate system, and the y-coordinate value in the X direction. r This represents the coordinate value in the Y direction of the reference station in a Cartesian coordinate system, z. r This represents the coordinate value in the Z direction of the reference station in the spatial rectangular coordinate system, x s This represents the coordinate value in the X direction of the satellite's spatial rectangular coordinate system, and the y-coordinate value. s This represents the coordinate value in the Y direction of the satellite in a Cartesian spatial coordinate system, z. s This represents the coordinate value in the Z direction of the satellite's spatial rectangular coordinate system.

3. The method according to claim 1, characterized in that, The single-epoch error equation is: The error equation for a single star i is: Where l is the first coefficient corresponding to lδx, which is a small quantity in the x-axis; m is the second coefficient corresponding to mδy, which is a small quantity in the y-axis; n is the third coefficient corresponding to nδz, which is a small quantity in the z-axis; and mf is the tropospheric mapping function. It is the deviation between the observed value and the true value of satellite i. It represents the coordinate change of satellite i; the superscript i = 1 to k represents the satellite number.

4. The method according to claim 3, characterized in that, When there are enough observations and redundant observations, the error value is obtained by solving the single-epoch error equation using the least squares method; and the above error value is used to filter the coordinates of the reference station to obtain the real-time estimated coordinates of each reference station.

5. The method according to claim 4, characterized in that, During the filtering process, prior constraint information is added to the reference station coordinates. This prior constraint information is calculated based on the historical observation data of the base station and includes the base station coordinates and the rate of change of coordinates.

6. The method according to claim 1, characterized in that, The coordinates of a single station obtained by PPP precise single-point positioning calculation are compared with the real-time estimated coordinates of the reference station, and the reference station with the smallest displacement is taken as the reference station that has not moved.

7. A CORS network solution system that takes into account changes in reference station coordinates, comprising: Double-difference observation models, including double-difference pseudorange observation equations without ionospheric assemblies. Double-difference phase carrier observation equations combined with ionosphere-free The real-time reference station coordinate estimation module is used to estimate coordinates based on the single-epoch error equation and the double-difference pseudorange observation equation. Double-difference phase carrier observation equation The real-time estimated coordinates of each reference station are obtained through calculation; The reference station movement determination module is used to calculate the single-station coordinates of each reference station through PPP precise single-point positioning, and compare them with the real-time estimated coordinates of the reference stations to determine the reference stations that have not moved. The rover positioning and calculation module is used to use a stationary reference station as the main reference station and perform positioning and calculation on the rover station based on the location information uploaded by the rover station in real time.

8. The system according to claim 7, characterized in that, In the formula, ρ is the geometric distance between the station and the satellite. It is a double-difference geometric distance. εp represents the double-difference tropospheric delay, εP represents the double-difference pseudorange random noise, e1 represents the double-difference narrow-lane coefficient for the ionospheric combination, and e2 represents the double-difference wide-lane coefficient for the ionospheric combination. For double-difference narrow alley ambiguity, εL represents the double-difference wide-lane ambiguity, εL represents the double-difference phase random noise, and the station-satellite geometric distance ρ represents the real-time coordinates of the reference station, which is used as the parameter to be estimated. In the formula, x r This represents the coordinate value in the X direction of the reference station in a Cartesian coordinate system, and the y-coordinate value in the X direction. r This represents the coordinate value in the Y direction of the reference station in a Cartesian coordinate system, z. r This represents the coordinate value in the Z direction of the reference station in the spatial rectangular coordinate system, x s This represents the coordinate value in the X direction of the satellite's spatial rectangular coordinate system, and the y-coordinate value. s This represents the coordinate value in the Y direction of the satellite in a Cartesian spatial coordinate system, z. s This represents the coordinate value in the Z direction of the satellite's spatial rectangular coordinate system.

9. The system according to claim 7, characterized in that, The single-epoch error equation is: The error equation for a single star i is: Where l is the first coefficient corresponding to lδx, which is a small quantity in the x-axis; m is the second coefficient corresponding to mδy, which is a small quantity in the y-axis; n is the third coefficient corresponding to nδz, which is a small quantity in the z-axis; and mf is the tropospheric mapping function. It is the deviation between the observed value and the true value of satellite i. It represents the coordinate change of satellite i; the superscript i = 1 to k represents the satellite number.

10. A computer-readable medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the CORS network solution method that takes into account the changes in reference station coordinates as described in any one of claims 1 to 6.

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