Satellite-ground fusion positioning method and device

Abstract

The application provides a satellite-ground fusion positioning method and device, which comprises the following steps: performing RTK positioning calculation based on the observation value of a receiving end, the observation value of a reference station and the coordinates of the reference station to obtain RTK position and RTK accuracy information; taking the RTK position as the initial position of PPP positioning calculation, and determining the prior accuracy information corresponding to the initial position according to the RTK position accuracy information; performing PPP positioning calculation based on the initial position, the prior accuracy information, the observation value of the receiving end, broadcast ephemeris and Beidou PPP-B2b satellite-based correction number to obtain PPP position and PPP position accuracy information; performing position domain fusion calculation based on the RTK position, the PPP position, the RTK position accuracy information and the PPP position accuracy information to obtain the fusion positioning state of the current observation epoch, and extrapolating the fusion positioning state to obtain the prior state and prior accuracy information of the next observation epoch; and performing RTK positioning calculation of the next observation epoch based on the prior state and the prior accuracy information.

Description

Technical Field

[0001] This invention relates to the field of satellite-to-ground fusion positioning technology, and in particular to a satellite-to-ground fusion positioning method and apparatus. Background Technology

[0002] Global Navigation Satellite System (GNSS) high-precision positioning technology is widely used in surveying, transportation, marine monitoring, and mobile equipment navigation. The BeiDou PPP-B2b service broadcasts satellite-based correction information such as orbit corrections and clock corrections, enabling positioning terminals to obtain high-precision position results based on Precise Point Positioning (PPP) without relying on terrestrial communication networks. However, PPP-B2b positioning typically involves initialization and convergence processes. In scenarios such as urban canyons, satellite obstruction, or dynamic environmental changes, the convergence speed may decrease or the observation quality may degrade due to reduced available observation information, thus affecting the continuity and reliability of the positioning results.

[0003] Real-time kinematic (RTK) positioning utilizes differential observation information between a reference station and the receiver to quickly obtain high-precision location results. However, RTK positioning relies on reference station services and communication links. When communication links are limited, interrupted, or reference station services are unavailable, the continuous output of positioning results can be easily affected.

[0004] In existing technologies, PPP-B2b positioning and RTK positioning are usually operated independently or jointly modeled and fused at the level of raw observations. The independent operation method makes it difficult to fully utilize the positioning characteristics of each in the positioning process; while fusing at the level of raw observations usually involves more complex observation models, more parameters to be estimated, and higher requirements for data synchronization and error modeling, which is not conducive to engineering deployment and expanded applications. Summary of the Invention

[0005] This invention provides a satellite-to-ground fusion positioning method and apparatus to address the shortcomings of existing technologies where PPP-B2b positioning and RTK positioning are difficult to fuse in a low-complexity manner while simultaneously achieving positioning convergence speed and positioning continuity.

[0006] This invention provides a satellite-ground fusion positioning method, comprising: performing RTK positioning calculation based on receiver observations, reference station observations, and reference station coordinates to obtain RTK position and RTK accuracy information; using the RTK position as the initial position for PPP positioning calculation, and determining prior accuracy information corresponding to the initial position based on the RTK position accuracy information; and performing PPP positioning calculation based on the initial position, the prior accuracy information, receiver observations, the broadcast ephemeris, and the BeiDou PPP-B2b satellite-based corrections to obtain PPP position and PPP position accuracy information. Based on the RTK location, the PPP location, the RTK location accuracy information, and the PPP location accuracy information, a location domain fusion calculation is performed to obtain the fused positioning state of the current observation epoch. The fused positioning state is then extrapolated to obtain the prior state and prior accuracy information of the next observation epoch. Based on the prior state and the prior accuracy information, the RTK positioning calculation for the next observation epoch is performed. If the RTK location of the next observation epoch cannot be obtained, the PPP positioning calculation for the next observation epoch is performed based on the prior state and the prior accuracy information.

[0007] According to the satellite-to-ground fusion positioning method provided by the present invention, the step of performing RTK positioning calculation based on receiver observations, reference station observations, and reference station coordinates to obtain RTK position and RTK accuracy information includes: constructing a differential observation model between the receiver and the reference station based on the reference station coordinates, the reference station observations, and the receiver observations; performing position parameter calculation and carrier phase ambiguity calculation based on the differential observation model to obtain the RTK position and ambiguity fixation results; determining the positioning state corresponding to the RTK position according to the ambiguity fixation results, and determining the RTK position accuracy information according to the positioning state and positioning post-verification variance information.

[0008] According to the satellite-to-ground fusion positioning method provided by the present invention, determining the RTK position accuracy information based on the positioning state and the post-positioning variance information includes: determining first RTK position accuracy information based on the post-positioning variance information when the positioning state is a fixed solution state; and determining second RTK position accuracy information based on the post-positioning variance information when the positioning state is a floating-point solution state; wherein the position domain fusion weight corresponding to the first RTK position accuracy information is greater than the position domain fusion weight corresponding to the second RTK position accuracy information.

[0009] According to the satellite-ground fusion positioning method provided by the present invention, obtaining the PPP position and PPP position accuracy information includes: matching data based on the BeiDou PPP-B2b satellite-based corrections and the broadcast ephemeris, and recovering the precise satellite orbit and precise satellite clock bias according to the matching results; preprocessing and error correction of the receiver observations to obtain corrected observations; constructing a PPP positioning observation model based on the initial position, the corrected observations, the precise satellite orbit, and the precise satellite clock bias; and calculating positioning parameters based on the PPP positioning observation model and the prior accuracy information to obtain the PPP position and the PPP position accuracy information.

[0010] According to the satellite-ground fusion positioning method provided by the present invention, the step of matching data based on the BeiDou PPP-B2b satellite-based corrections and the broadcast ephemeris, and recovering the precise satellite orbit and precise satellite clock bias based on the matching result, includes: determining a broadcast ephemeris that matches the BeiDou PPP-B2b satellite-based corrections based on the data age of the BeiDou PPP-B2b satellite-based corrections; converting the satellite orbit corrections in the BeiDou PPP-B2b satellite-based corrections to a ground-fixed coordinate system, and correcting the satellite orbits in the matched broadcast ephemeris based on the converted satellite orbit corrections to obtain the precise satellite orbits; and correcting the satellite clock biases in the matched broadcast ephemeris based on the satellite clock bias corrections in the BeiDou PPP-B2b satellite-based corrections to obtain the precise satellite clock biases.

[0011] According to the satellite-to-ground fusion positioning method provided by the present invention, the step of calculating positioning parameters based on the PPP positioning observation model and the prior accuracy information to obtain the PPP position and the PPP position accuracy information includes: determining the prior accuracy of the position parameters to be estimated in the PPP positioning observation model according to the prior accuracy information; recursively estimating the position parameters to be estimated, including the position parameters to be estimated, receiver clock error, zenith tropospheric residual delay, and carrier phase ambiguity parameters, based on the PPP positioning observation model and the prior accuracy of the position parameters to be estimated, to obtain the PPP position; and determining the PPP position accuracy information based on the result of the recursive estimation.

[0012] According to the satellite-to-ground fusion positioning method provided by the present invention, the step of performing position domain fusion calculation based on the RTK position, the PPP position, the RTK position accuracy information, and the PPP position accuracy information to obtain the fusion positioning state of the current observation epoch includes: constructing fusion position state parameters for fusion calculation of the RTK position and the PPP position, wherein the fusion position state parameters include receiver three-dimensional position parameters; constructing position domain observation equations by using the RTK position and the PPP position as position measurement values ​​of the fusion position state parameters respectively; determining observation noise information corresponding to each position measurement value in the position domain observation equations according to the RTK position accuracy information and the PPP position accuracy information; and solving the fusion position state parameters based on the position domain observation equations and the observation noise information to obtain the fusion positioning state of the current observation epoch.

[0013] This invention also provides a satellite-ground fusion positioning device, comprising: a first positioning calculation module, used to perform RTK positioning calculation based on receiver observations, reference station observations, and reference station coordinates to obtain RTK position and RTK accuracy information; a priori module, used to use the RTK position as the initial position for PPP positioning calculation, and to determine priori accuracy information corresponding to the initial position based on the RTK position accuracy information; and a second positioning calculation module, used to perform PPP positioning calculation based on the initial position, the priori accuracy information, the receiver observations, the broadcast ephemeris, and the BeiDou PPP-B2b satellite-based corrections to obtain PPP position and PP accuracy information. The first module provides location accuracy information; the second module provides a fusion module for performing location domain fusion calculation based on the RTK location, the PPP location, the RTK location accuracy information, and the PPP location accuracy information to obtain the fused positioning state of the current observation epoch, and extrapolating the fused positioning state to obtain the prior state and prior accuracy information of the next observation epoch; the third module provides a positioning calculation module for performing RTK positioning calculation of the next observation epoch based on the prior state and the prior accuracy information, and for performing PPP positioning calculation of the next observation epoch based on the prior state and the prior accuracy information when the RTK location of the next observation epoch cannot be obtained.

[0014] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement any of the above-described satellite-to-ground fusion positioning methods.

[0015] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements any of the above-described satellite-to-ground fusion positioning methods.

[0016] The satellite-to-ground fusion positioning method and apparatus provided by this invention obtains RTK position and RTK position accuracy information by performing RTK positioning calculation based on reference station observations, reference station coordinates, and receiver observations. The RTK position is used as the initial position for PPP positioning calculation, and corresponding prior accuracy information is determined based on the RTK position accuracy information. This allows PPP positioning calculation to utilize the position prior formed by RTK positioning, reducing convergence waiting caused by uncertain initial position during the PPP-B2b positioning initialization phase. Furthermore, position domain fusion calculation based on the RTK position, PPP position, and their respective position accuracy information can comprehensively utilize the results and reliability of RTK positioning and PPP-B2b positioning without complex joint modeling of the original observations of the two types of positioning services. Simultaneously, by using the prior state and prior accuracy information obtained by extrapolating the fused positioning state for positioning calculation in the next observation epoch, and using it for PPP positioning calculation when RTK positioning is unavailable, the positioning process can maintain continuous recursion even when the RTK service state changes. Therefore, the present invention can improve the convergence performance of PPP-B2b positioning with lower fusion processing complexity and enhance the continuity and reliability of satellite-ground fusion positioning. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a flowchart of the satellite-ground fusion positioning method; Figure 2 The flowchart illustrates an example of the present invention of performing RTK positioning calculation based on receiver observations, reference station observations, and reference station coordinates to obtain RTK position and RTK accuracy information. Figure 3 A flowchart illustrating an example of the present invention for obtaining PPP location and PPP location accuracy information is shown. Figure 4 The flowchart illustrates an example of the present invention of performing location domain fusion calculation based on the RTK location, the PPP location, the RTK location accuracy information, and the PPP location accuracy information to obtain the fused positioning state of the current observation epoch. Figure 5 A schematic diagram showing the positioning result of an example of the present invention is illustrated; Figure 6 A structural block diagram of the satellite-to-ground fusion positioning device is shown. Figure 7 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0020] Figure 1 This is a flowchart of the satellite-ground fusion positioning method.

[0021] like Figure 1 As shown, the method includes operations S110~S150.

[0022] During operation S110, RTK positioning calculation is performed based on the receiver observations, reference station observations, and reference station coordinates to obtain RTK position and RTK accuracy information.

[0023] The receiving end is a positioning terminal set up at the location of the object to be located and used to receive satellite navigation signals. The object to be located can be a vehicle, unmanned equipment, surveying equipment, mobile monitoring equipment, or other equipment that needs to obtain its location. The receiving end's observation values ​​are observation data formed by the receiving end based on satellite navigation signals, which may include at least one of pseudorange observation values, carrier phase observation values, Doppler observation values, and signal quality information.

[0024] A reference station is a satellite navigation observation station with a known location used to provide differential reference information for positioning at the receiving end. Reference station coordinates are predetermined spatial coordinates of the reference station, such as three-dimensional coordinates expressed in an Earth-fixed coordinate system. Reference station observations are observation data generated by the reference station based on received satellite navigation signals, and may include at least one of pseudorange observations, carrier phase observations, Doppler observations, and signal quality information. Reference station observations and receiving end observations may correspond to the same observation epoch or observation epochs that can be time-matched.

[0025] In some examples, before performing RTK positioning calculations, the coordinate framework of the reference station coordinates and the position parameters of the receiver involved in the positioning calculation can be unified to ensure that they are under the same coordinate reference. Subsequently, based on the reference station coordinates, reference station observations, and receiver observations, and taking advantage of the known position of the reference station, differential processing is performed on the satellite signals jointly observed by the receiver and the reference station to reduce or eliminate the impact of satellite clock errors, propagation path errors, and other related errors on the receiver's positioning results.

[0026] The RTK position at the current observation epoch is obtained through the above RTK positioning calculation. The RTK position is used to characterize the spatial position of the receiver, which can be the three-dimensional coordinates of the receiver in a preset coordinate system, or a position expression result that can be converted to three-dimensional coordinates.

[0027] During the RTK positioning calculation process, RTK accuracy information corresponding to the RTK position can be obtained based on the quality of the observation data involved in the calculation, the calculation residual information, and the positioning parameter estimation results.

[0028] In operation S120, the RTK position is used as the initial position for PPP positioning calculation, and the prior accuracy information corresponding to the initial position is determined based on the RTK position accuracy information.

[0029] The initial position for PPP positioning calculation is the initial estimated position of the receiver used when estimating PPP positioning parameters. It is used to determine the approximate geometric relationship between the receiver and the satellite, and to provide a starting basis for iterative estimation of the receiver position parameters. The RTK position is the spatial position of the receiver determined based on receiver observations, reference station observations, and reference station coordinates.

[0030] When RTK positioning and PPP positioning use the same coordinate frame, the RTK position can be directly set as the initial value of the receiver position parameter in the PPP positioning. When they use different coordinate frames, the RTK position can be transformed to make the transformed RTK position consistent with the coordinate frame used in the PPP positioning, and the transformed RTK position can be set as the initial position.

[0031] Prior accuracy information is used to characterize the degree of uncertainty of the initial position. RTK position accuracy information can be position covariance information, position variance information, position standard deviation information, or equivalent accuracy index. Accordingly, when the RTK position accuracy information is position covariance information, the prior covariance information of the initial position can be determined based on the position covariance information; when the RTK position accuracy information is an equivalent accuracy index, the equivalent accuracy index can be converted into the prior accuracy information corresponding to the initial position based on a preset accuracy transformation relationship.

[0032] Initial position and prior accuracy information together characterize the receiver's position basis at the start of PPP positioning calculation and the reliability of that position basis. The smaller the position uncertainty represented by the RTK position accuracy information, the higher the prior reliability of the initial position in PPP positioning calculation; the greater the position uncertainty represented by the RTK position accuracy information, the lower the prior constraint of the initial position in PPP positioning calculation.

[0033] Therefore, PPP positioning calculation can not only use RTK position to form an initial estimate of the receiver position parameters, but also combine RTK position accuracy information to determine the reliability of the initial estimate, thus providing a priori position basis for positioning parameter estimation based on BeiDou PPP-B2b satellite-based corrections.

[0034] In operation S130, PPP positioning is calculated based on the initial position, prior accuracy information, receiver observations, broadcast ephemeris, and BeiDou PPP-B2b satellite-based corrections to obtain PPP position and PPP position accuracy information.

[0035] Broadcast ephemeris is navigation data broadcast by navigation satellites, used to describe the satellite's orbital and clock states. BeiDou PPP-B2b satellite-based corrections are correction information broadcast by BeiDou satellites, used to correct the satellite orbits and clocks corresponding to the broadcast ephemeris. These corrections may include satellite orbit corrections and satellite clock corrections, as well as other correction information related to positioning calculations.

[0036] Specifically, the broadcast orbits and broadcast clock biases of each participating positioning satellite can be determined based on the broadcast ephemeris, and then corrected using BeiDou PPP-B2b satellite-based corrections to obtain precise satellite orbits and precise satellite clock biases for PPP positioning calculations. For BeiDou PPP-B2b satellite-based corrections in different data formats, they can be matched with the corresponding broadcast ephemeris based on the data age, satellite identifier, or version information of the corrections to ensure that the correction information used corresponds to the satellite navigation data.

[0037] During PPP positioning calculations, the receiver observations can undergo observation quality checks and error correction. Observation quality checks may include at least one of the following: anomaly identification, gross error removal, or carrier phase cycle slip detection. Error correction may include at least one of the following: satellite orbit error correction, satellite clock error correction, tropospheric delay correction, Earth rotation effect correction, relativistic effect correction, or antenna-related error correction. The processed receiver observations are used to characterize the distance or phase relationship between the receiver and the participating positioning satellites.

[0038] In one implementation, a PPP positioning observation model can be established based on error-corrected pseudorange and carrier phase observations, and at least one of the following parameters—receiver position parameters, receiver clock error parameters, tropospheric residual delay parameters, and carrier phase ambiguity parameters—can be jointly estimated. In another implementation, a preliminary position estimate can be made based on pseudorange observations, and the receiver position parameters can be recursively corrected based on carrier phase observations. Positioning parameter estimation can be achieved through least squares estimation, Kalman filtering, information filtering, or other methods that allow for state estimation based on observation data and prior information. Through PPP positioning calculation, the PPP position of the receiver in a preset coordinate system can be determined, and then the PPP position accuracy information corresponding to the PPP position can be determined using the parameter covariance, position variance, position standard deviation, or equivalent accuracy index formed during the positioning parameter estimation process.

[0039] In operation S140, a position domain fusion solution is performed based on RTK position, PPP position, RTK position accuracy information and PPP position accuracy information to obtain the fused positioning state of the current observation epoch. The fused positioning state is then extrapolated to obtain the prior state and prior accuracy information of the next observation epoch.

[0040] RTK and PPP locations can be used as two types of positioning results inputs to the receiver's position state. The degree of constraint of each positioning result input in the fusion solution is determined based on the RTK and PPP location accuracy information. When the uncertainty represented by the location accuracy information is small, the constraint effect of the corresponding location result on the fused positioning state is strong; when the uncertainty represented by the location accuracy information is large, the constraint effect of the corresponding location result on the fused positioning state is correspondingly weakened. Therefore, the fused positioning state of the current observation epoch can be obtained by comprehensively utilizing the location and reliability information provided by the RTK and PPP positioning results within the same location domain.

[0041] Location domain fusion can be achieved by combining multiple location results and their accuracy information for state estimation. For example, weighted least squares estimation, Kalman filtering, information filtering, or root mean square information filtering can be used for fusion. When using filtering for fusion, the receiver's location state can be taken as the estimated state, and the estimated state can be updated based on the RTK location, PPP location, and corresponding location accuracy information to determine the receiver's location and fusion state accuracy information at the current observation epoch.

[0042] Extrapolating the fused positioning state refers to determining the initial state information used by the receiver in the next observation epoch when performing positioning calculations, based on the fused positioning state of the current observation epoch. When the fused positioning state includes the receiver's position state, the initial position of the next observation epoch can be determined based on the position state. When the fused positioning state further includes velocity state, the initial position and / or initial velocity of the next observation epoch can be determined based on the position state, velocity state, and the time interval between adjacent observation epochs, thus forming a priori state. Furthermore, the priori accuracy information can be determined based on the fused state accuracy information of the current observation epoch, or adjusted in conjunction with the time interval and motion state uncertainties used in the state extrapolation process.

[0043] In operation S150, the RTK positioning solution for the next observation epoch is performed based on the prior state and prior accuracy information. If the RTK position for the next observation epoch cannot be obtained, the PPP positioning solution for the next observation epoch is performed based on the prior state and prior accuracy information.

[0044] In situations such as communication link interruption, reference station service malfunction, or insufficient observation conditions, RTK positioning may fail to obtain an RTK position usable for positioning output. In such cases, prior state and prior accuracy information are used in the PPP positioning solution for the next observation epoch. This allows the PPP positioning solution to inherit the fused state formed in the previous observation epoch, without having to rely solely on the approximate position to re-estimate positioning parameters. This maintains continuous output of the receiver's positioning results during periods when RTK positioning is unavailable.

[0045] Therefore, when RTK positioning is available, its fast positioning speed is utilized and combined with fused prior information for continuous positioning; when RTK positioning is unavailable, PPP positioning is used to continue the positioning process, enabling satellite-based positioning services and ground-based positioning services to collaboratively complete continuous positioning based on the state transfer relationship between adjacent observation epochs.

[0046] Based on the above setup, by using the RTK location as the initial location for PPP positioning calculation and utilizing the RTK location accuracy information to determine the prior accuracy information corresponding to the initial location, the PPP positioning calculation can inherit the location foundation and reliability provided by ground-based positioning, which is beneficial to improving the initialization and convergence performance of BeiDou PPP-B2b positioning. By performing position domain fusion calculation based on RTK location, PPP location, and their respective location accuracy information, the collaborative utilization of satellite-based positioning results and ground-based positioning results can be achieved without complex joint modeling of the original observation data of the two positioning methods, reducing the complexity of fusion processing. Furthermore, by using the prior state and prior accuracy information formed by extrapolating the fused positioning state for the positioning calculation of the next observation epoch, and by having the PPP positioning calculation take over the positioning process when the RTK location cannot be obtained, the continuity and reliability of positioning output can be improved under conditions of RTK service status changes or communication limitations.

[0047] Figure 2 The flowchart illustrates an example of the present invention of performing RTK positioning calculation based on receiver observations, reference station observations, and reference station coordinates to obtain RTK position and RTK accuracy information.

[0048] like Figure 2 As shown, operation S110 includes operations S210~S230.

[0049] In operation S210, a differential observation model between the receiver and the reference station is constructed based on the reference station coordinates, reference station observations, and receiver observations.

[0050] According to an embodiment of the present invention, after unifying the coordinate framework corresponding to the reference station coordinates and the receiver position parameters, an RTK differential observation model is established using the reference station observations and the receiver observations. RTK positioning can be differentially calculated based on pseudorange observations and carrier phase observations. This embodiment takes a double-differential carrier phase model as an example, and the differential observation model is expressed as follows:

[0051] In the formula, It is a double difference operator; The wavelength of the carrier wave; These are the double-difference carrier phase observations between the receiver and the reference station; This is the corresponding double-difference geometric distance; For the corresponding double-difference integer ambiguity parameters; , , These are the orbital error, residual ionospheric delay, and residual tropospheric delay remaining after calculating the double difference between the receiver and the reference station, respectively. It is the sum of errors such as multipath error and measurement noise.

[0052] By constructing a differential observation model, some common errors under the condition of joint observation by the receiver and the reference station can be reduced or eliminated, providing an observation basis for the calculation of receiver position parameters and carrier phase ambiguity parameters.

[0053] In operation of S220, position parameter calculation and carrier phase ambiguity calculation are performed based on the differential observation model to obtain fixed RTK position and ambiguity results.

[0054] According to an embodiment of the present invention, based on a differential observation model, the position parameters and double-difference integer ambiguity parameters of the receiver are estimated, and the estimated double-difference integer ambiguity parameters are fixed to obtain a fixed ambiguity result. The position parameter calculation can be implemented using least squares estimation, recursive filtering estimation, or other position parameter estimation methods based on the differential observation model; the carrier phase ambiguity calculation can be implemented using an integer ambiguity fixing method.

[0055] The obtained RTK position can be represented as:

[0056] In the formula, For RTK location; , , These are the three-dimensional coordinates of the receiver in the Earth-fixed coordinate system; superscript This indicates the matrix transpose.

[0057] In operation S230, the positioning state corresponding to the RTK position is determined based on the ambiguity fixation result, and the RTK position accuracy information is determined based on the positioning state and the post-positioning variance information.

[0058] According to embodiments of the present invention, based on the location parameter calculation results, the posterior variance information of the RTK location can be extracted. In one embodiment, the posterior variance information of the location can be represented by the covariance matrix corresponding to the RTK location:

[0059] In the formula, This is the covariance matrix corresponding to the RTK position; Represents the mathematical expectation; For RTK location; This represents the actual location of the receiving end.

[0060] In one illustrative embodiment, the positioning state includes a fixed solution state and a floating-point solution state. The fixed solution state indicates that the carrier phase ambiguity has a fixed result, while the floating-point solution state indicates that the carrier phase ambiguity has not obtained a fixed result and is used in the position parameter calculation as floating-point parameters.

[0061] When the positioning state is a fixed solution state, the first RTK position accuracy information is determined based on the post-verification variance information; when the positioning state is a floating-point solution state, the second RTK position accuracy information is determined based on the post-verification variance information. Since the RTK position in the fixed solution state has a relatively high degree of reliability, the position domain fusion weight corresponding to the first RTK position accuracy information is greater than the position domain fusion weight corresponding to the second RTK position accuracy information. Therefore, during the position domain fusion calculation process, the RTK position in the fixed solution state has a strong constraint on the fused positioning state, while the RTK position in the floating-point solution state has a relatively weak constraint on the fused positioning state.

[0062] Furthermore, in one embodiment, the positioning state also includes an unavailable state. The unavailable state characterizes the failure to obtain an RTK location that meets the positioning requirements, or the obtained RTK location lacks sufficient reliability for location domain fusion calculation. When the positioning state is unavailable, location domain fusion calculation is performed based on the PPP location and PPP location accuracy information to determine the fused positioning state. Thus, when RTK positioning cannot provide reliable location results, the influence of insufficiently reliable RTK locations on the fused positioning state can be avoided, and the continuous output of positioning results can be maintained using the PPP location.

[0063] Figure 3 A flowchart illustrating an example of the present invention for obtaining PPP location and PPP location accuracy information is shown.

[0064] like Figure 3 As shown, operation S130 includes operations S310~S340.

[0065] When operating S310, data matching is performed based on the BeiDou PPP-B2b satellite-based correction data and the broadcast ephemeris, and the precise satellite orbit and precise satellite clock error are restored according to the matching results.

[0066] The BeiDou PPP-B2b satellite-based corrections can include satellite orbit corrections and satellite clock bias corrections. Broadcast ephemeris is used to provide the broadcast orbit and broadcast clock bias of the corresponding satellite. By matching the BeiDou PPP-B2b satellite-based corrections with the broadcast ephemeris, and correcting the broadcast ephemeris using the matching corrections, precise satellite orbits and precise satellite clock biases can be obtained for PPP positioning calculations.

[0067] Specifically, operation S310 may include operations S311 to S313.

[0068] During operation S311, the broadcast ephemeris that matches the BeiDou PPP-B2b satellite-based correction data is determined based on the data age of the BeiDou PPP-B2b satellite-based correction data.

[0069] According to an embodiment of the present invention, broadcast ephemeris data can be matched based on information such as the data age of the PPP-B2b corrections, and the satellite orbit corrections for the star-fixed system can be converted into Earth-fixed system corrections:

[0070] In the formula, For satellite orbital corrections in the Earth-fixed system; These are satellite orbit corrections in the BeiDou PPP-B2b satellite-based corrections. , , These are the unit vectors for the satellite's radial, tangential, and normal directions, respectively. Indicates satellite identifier.

[0071] In operation S312, the satellite orbit corrections in the BeiDou PPP-B2b satellite-based corrections are converted to the Earth-fixed coordinate system, and the satellite orbits in the matching broadcast ephemeris are corrected based on the converted satellite orbit corrections to obtain precise satellite orbits.

[0072] According to an embodiment of the present invention, the satellite orbit corrections converted to the Earth-fixed coordinate system are matched with the satellite orbits in the broadcast ephemeris to obtain the precise satellite orbits:

[0073] In the formula, For satellite orbits in broadcast ephemeris; For satellite orbital corrections in the Earth-fixed system; To restore the obtained precise satellite orbit.

[0074] In operation S313, the satellite clock error in the matching broadcast ephemeris is corrected based on the satellite clock error correction in the BeiDou PPP-B2b satellite-based correction data to obtain the precise satellite clock error.

[0075] According to an embodiment of the present invention, for satellite clock bias, the precise satellite clock bias can be recovered based on the satellite clock bias correction in the BeiDou PPP-B2b satellite-based correction and the satellite clock bias in the broadcast ephemeris:

[0076] In the formula, For the restored precision satellite clock bias; For satellite clock bias in broadcast ephemeris; This refers to the satellite clock error correction in the BeiDou PPP-B2b satellite-based correction data. It is the speed of light.

[0077] In operation S320, the received observations are preprocessed and error corrected to obtain corrected observations.

[0078] According to embodiments of the present invention, the preprocessing of the receiver observations may include observation epoch filtering, cutoff elevation angle setting, gross error removal, and cycle slip detection. Error correction of the receiver observations may include Earth rotation correction, relativistic correction, antenna phase center correction, antenna winding correction, and tropospheric empirical model correction.

[0079] Furthermore, based on the preprocessed and error-corrected receiver observations, dual-frequency ionospheric-free combined observations can be constructed as corrected observations for the establishment of the PPP positioning observation model.

[0080] When operating the S330, a PPP positioning observation model is constructed based on the initial position, corrected observations, precise satellite orbit, and precise satellite clock error.

[0081] According to an embodiment of the present invention, the PPP positioning observation model is used to characterize the residual relationship between corrected observation values ​​and calculated values ​​determined based on precise satellite orbits, precise satellite clock errors, and positioning parameters to be estimated. In this embodiment, the PPP positioning observation model is represented by a PPP residual model, which includes a pseudorange pre-a priori residual equation and a carrier phase pre-a priori residual equation.

[0082] Specifically, the initial position can be a rough location of the receiver, used to calculate the geometric distance between the receiver and the satellite by combining it with a precise satellite orbit; the corrected observations include ionospheric pseudorange observations and ionospheric carrier phase observations formed after preprocessing and error correction. For dual-frequency ionospheric PPP based on PPP-B2b, any satellite The corresponding PPP location observation model is represented as follows:

[0083] In the formula, and Satellites The corresponding PPP pseudorange pre-aware residuals and PPP carrier phase pre-aware residuals; and Receiving end Corresponding satellite Ionospheric pseudorange observations and ionospheric carrier phase observations; Indicates an assembly without an ionosphere; The geometric distance is calculated based on the precise satellite orbit and initial position; The speed of light; This refers to the receiver clock bias of the corresponding satellite navigation system at the receiving end; For precision satellite clock bias; For tropospheric mapping functions; The residual tropospheric delay in the zenith direction at the receiving end; Satellites under ionospheric conditions The corresponding floating-point fuzziness parameter.

[0084] When operating the S340, the positioning parameters are calculated based on the PPP positioning observation model and prior accuracy information to obtain the PPP location and PPP location accuracy information.

[0085] Specifically, operation S340 may include operations S341 to S343.

[0086] In operation S341, the prior accuracy of the location parameters to be estimated in the PPP positioning observation model is determined based on the prior accuracy information.

[0087] According to an embodiment of the present invention, the prior accuracy corresponding to the three-dimensional position parameters of the receiver at the start of PPP positioning calculation can be determined based on prior accuracy information, so as to characterize the degree of constraint of the initial position on the estimation of positioning parameters.

[0088] In operation S342, based on the PPP positioning observation model and the prior accuracy of the position parameters to be estimated, the parameters to be estimated, including the position parameters to be estimated, receiver clock error, zenith tropospheric residual delay and carrier phase ambiguity parameters, are recursively estimated to obtain the PPP position.

[0089] The tropospheric delay can be corrected using an empirical model, and the residual tropospheric delay in the zenith direction can be estimated. The parameters to be estimated in the PPP positioning solution can be expressed as:

[0090] In the formula, The vector of parameters to be estimated in the PPP positioning solution; These are the three-dimensional position parameters of the receiving end; This refers to the receiver clock bias of the corresponding satellite navigation system at the receiving end; The residual tropospheric delay in the zenith direction at the receiving end; These are the ionosphere-free combined floating-point ambiguity parameters for each satellite; superscript This indicates the matrix transpose.

[0091] Based on the initial position, prior accuracy information, corrected observations, precise satellite orbit, and precise satellite clock error, the design matrix and residual vector corresponding to the PPP positioning observation model can be formed. Then, the parameters to be estimated are estimated using a recursive filtering method to obtain the PPP position of the receiver.

[0092] In operation S343, the PPP location accuracy information is determined based on the recursive estimation results.

[0093] The PPP location obtained by solving the PPP location observation model can be expressed as:

[0094] In the formula, For PPP location; , , These are the three-dimensional coordinates of the receiver in the Earth-fixed coordinate system; superscript This indicates the matrix transpose.

[0095] Correspondingly, the covariance matrix corresponding to the PPP location can be extracted:

[0096] In the formula, This is the covariance matrix corresponding to the PPP location; Represents the mathematical expectation; For PPP location; This represents the actual location of the receiving end.

[0097] In one embodiment, the covariance matrix can be used as PPP location accuracy information; in other embodiments, the location variance, location standard deviation or equivalent accuracy index can be determined based on the covariance matrix, and the determined accuracy parameters can be used as PPP location accuracy information.

[0098] Figure 4 The flowchart illustrates an example of the present invention of performing location domain fusion calculation based on RTK location, PPP location, RTK location accuracy information and PPP location accuracy information to obtain the fused positioning state of the current observation epoch.

[0099] like Figure 4 As shown, operation S140 includes operations S410 to S440.

[0100] In operation S410, a fused position state parameter is constructed for the fusion calculation of RTK position and PPP position. The fused position state parameter includes the receiver's three-dimensional position parameter.

[0101] According to an embodiment of the present invention, in the location domain fusion solution, the actual location of the receiver can be used as the state to be estimated to construct fused location state parameters:

[0102] In the formula, These are the fused position status parameters corresponding to the actual position of the receiving end; , , These are the three-dimensional position parameters of the receiver in the Earth-fixed coordinate system; superscript This indicates the matrix transpose.

[0103] When operating the S420, the RTK location and PPP location are used as measured values ​​of the fused location state parameters to construct the location domain observation equation.

[0104] According to an embodiment of the present invention, the PPP position obtained by PPP positioning calculation and the RTK position obtained by RTK positioning calculation can be used as the measured values ​​of the true position of the receiver, and a position domain observation equation can be constructed:

[0105] In the formula, For PPP location; For RTK location; To fuse position and state parameters; The observation noise corresponding to the PPP location; This represents the observation noise corresponding to the RTK location.

[0106] When operating the S430, the observation noise information corresponding to the position domain observation equation is determined based on the RTK position accuracy information and the PPP position accuracy information.

[0107] Specifically, the observation noise corresponding to the PPP location and the observation noise corresponding to the RTK location satisfy the following conditions:

[0108]

[0109] In the formula, This is the covariance matrix corresponding to the PPP location; This is the covariance matrix corresponding to the RTK position; This represents a normal distribution.

[0110] Furthermore, the observation noise corresponding to the RTK position can be set according to the RTK solution status. Specifically, a fixed RTK solution corresponds to a smaller observation noise, a floating RTK solution corresponds to a larger observation noise, and no RTK position measurement values ​​are introduced when RTK is unavailable.

[0111] In operation S440, based on the position domain observation equation and observation noise information, the fused position state parameters are solved to obtain the fused positioning state of the current observation epoch.

[0112] Specifically, based on the location domain observation equation and observation noise information, the design matrix, observation residual vector, and weight matrix information required for root mean square information filtering are constructed, and the root mean square information filtering is used to solve the fused location state parameters to obtain the fused positioning state of the current observation epoch.

[0113] Figure 5 A schematic diagram showing the positioning result of an example of the present invention is illustrated.

[0114] like Figure 5 As shown, in the satellite-to-ground fusion positioning method provided by this invention, the position deviations corresponding to each coordinate component remain within a small range overall, and there is no significant deviation of the same degree as that of the standalone PPP-B2b positioning method. Therefore, by utilizing RTK position and its accuracy information to assist in PPP positioning calculation, and by performing position domain fusion based on RTK and PPP positions, while using the fused prior information for positioning calculation in subsequent observation epochs, the convergence performance of PPP-B2b positioning can be improved, the fluctuation of positioning results reduced, and the stability and reliability of continuous positioning processes enhanced.

[0115] The satellite-to-ground fusion positioning device provided by the present invention is described below. The XX device described below can be referred to in correspondence with the satellite-to-ground fusion positioning method described above.

[0116] Figure 6 A structural block diagram of the satellite-ground fusion positioning device is shown.

[0117] like Figure 6 The satellite-to-ground fusion positioning device 600 shown includes a first positioning calculation module 610, a priori module 620, a second positioning calculation module 630, a fusion module 640, and a third positioning calculation module 650.

[0118] The first positioning calculation module 610 is used to perform RTK positioning calculation based on the receiver observation value, the reference station observation value and the reference station coordinates to obtain RTK position and RTK accuracy information. The prior module 620 is used to take the RTK position as the initial position for PPP positioning calculation and determine the prior accuracy information corresponding to the initial position based on the RTK position accuracy information. The second positioning calculation module 630 is used to perform PPP positioning calculation based on the initial position, prior accuracy information, receiver observations, broadcast ephemeris and BeiDou PPP-B2b satellite-based corrections to obtain PPP position and PPP position accuracy information. The fusion module 640 is used to perform position domain fusion calculation based on RTK position, PPP position, RTK position accuracy information and PPP position accuracy information to obtain the fused positioning state of the current observation epoch, and extrapolate the fused positioning state to obtain the prior state and prior accuracy information of the next observation epoch. The third positioning and calculation module 650 is used to perform RTK positioning and calculation for the next observation epoch based on prior state and prior accuracy information, and to perform PPP positioning and calculation for the next observation epoch based on prior state and prior accuracy information when the RTK position for the next observation epoch cannot be obtained.

[0119] Figure 7 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 7 As shown, the electronic device may include a processor 710, a communications interface 720, a memory 730, and a communication bus 740. The processor 710, communications interface 720, and memory 730 communicate with each other via the communication bus 740. The processor 710 can call logical instructions from the memory 730 to execute a satellite-to-ground fusion positioning method.

[0120] Furthermore, the logical instructions in the aforementioned memory 730 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, essentially, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0121] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer is able to execute the satellite-ground fusion positioning method provided by the above methods.

[0122] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0123] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A satellite-ground fusion positioning method, characterized in that, include: RTK positioning is calculated based on the receiver observations, reference station observations, and reference station coordinates to obtain RTK position and RTK accuracy information. The RTK location is used as the initial location for PPP positioning calculation, and the prior accuracy information corresponding to the initial location is determined based on the RTK location accuracy information. Based on the initial position, the prior accuracy information, the receiver observations, the broadcast ephemeris, and the BeiDou PPP-B2b satellite-based corrections, PPP positioning is calculated to obtain the PPP position and PPP position accuracy information. Based on the RTK location, the PPP location, the RTK location accuracy information, and the PPP location accuracy information, a location domain fusion solution is performed to obtain the fused positioning state of the current observation epoch. The fused positioning state is then extrapolated to obtain the prior state and prior accuracy information of the next observation epoch. The RTK positioning solution for the next observation epoch is performed based on the prior state and the prior accuracy information. If the RTK position for the next observation epoch cannot be obtained, the PPP positioning solution for the next observation epoch is performed based on the prior state and the prior accuracy information.

2. The satellite-to-ground fusion positioning method according to claim 1, characterized in that, The RTK positioning calculation based on receiver observations, reference station observations, and reference station coordinates yields RTK position and RTK accuracy information, including: Based on the coordinates of the reference station, the observations of the reference station, and the observations of the receiver, a differential observation model between the receiver and the reference station is constructed. Based on the differential observation model, position parameters and carrier phase ambiguity are calculated to obtain the fixed RTK position and ambiguity results; The positioning state corresponding to the RTK position is determined based on the ambiguity fixing result, and the RTK position accuracy information is determined based on the positioning state and the post-positioning variance information.

3. The satellite-to-ground fusion positioning method according to claim 2, characterized in that, The RTK position accuracy information is determined based on the positioning status and the post-positioning variance information, including: When the positioning state is a fixed solution state, the first RTK position accuracy information is determined based on the positioning posterior variance information; When the positioning state is a floating-point solution state, the second RTK position accuracy information is determined based on the positioning posterior variance information; The location domain fusion weight corresponding to the first RTK location accuracy information is greater than the location domain fusion weight corresponding to the second RTK location accuracy information.

4. The satellite-to-ground fusion positioning method according to claim 1, characterized in that, The acquisition of PPP location and PPP location accuracy information includes: Data matching is performed based on the BeiDou PPP-B2b satellite-based corrections and the broadcast ephemeris, and the precise satellite orbit and precise satellite clock bias are restored based on the matching results; The received observations are preprocessed and error corrected to obtain corrected observations; Based on the initial position, the corrected observations, the precise satellite orbit, and the precise satellite clock error, a PPP positioning observation model is constructed. Based on the PPP positioning observation model and the prior accuracy information, the positioning parameters are calculated to obtain the PPP location and the PPP location accuracy information.

5. The satellite-to-ground fusion positioning method according to claim 4, characterized in that, The process of matching data based on the BeiDou PPP-B2b satellite-based corrections and the broadcast ephemeris, and restoring the precise satellite orbit and precise satellite clock bias based on the matching results, includes: Based on the data age of the BeiDou PPP-B2b satellite-based corrections, determine the broadcast ephemeris that matches the BeiDou PPP-B2b satellite-based corrections; The satellite orbit corrections in the BeiDou PPP-B2b satellite-based corrections are converted to the Earth-fixed coordinate system, and the satellite orbits in the matching broadcast ephemeris are corrected based on the converted satellite orbit corrections to obtain the precise satellite orbits. The satellite clock bias in the matching broadcast ephemeris is corrected based on the satellite clock bias correction in the BeiDou PPP-B2b satellite-based correction to obtain the precise satellite clock bias.

6. The satellite-to-ground fusion positioning method according to claim 4, characterized in that, The step of calculating positioning parameters based on the PPP positioning observation model and the prior accuracy information to obtain the PPP location and the PPP location accuracy information includes: The prior accuracy of the location parameters to be estimated in the PPP positioning observation model is determined based on the prior accuracy information. Based on the prior accuracy of the PPP positioning observation model and the estimated position parameters, the estimated parameters, including the estimated position parameters, receiver clock error, zenith tropospheric residual delay and carrier phase ambiguity parameters, are recursively estimated to obtain the PPP position. The PPP location accuracy information is determined based on the results of the recursive estimation.

7. The satellite-to-ground fusion positioning method according to claim 1, characterized in that, The step of performing location domain fusion calculation based on the RTK location, the PPP location, the RTK location accuracy information, and the PPP location accuracy information to obtain the fused positioning state of the current observation epoch includes: Construct fusion position state parameters for fusing the RTK location and the PPP location, the fusion position state parameters including receiver three-dimensional position parameters; Using the RTK location and the PPP location as the location measurement values ​​of the fused location state parameters, a location domain observation equation is constructed. Based on the RTK position accuracy information and the PPP position accuracy information, determine the observation noise information corresponding to each position measurement value in the position domain observation equation; Based on the location domain observation equation and the observation noise information, the fused location state parameters are solved to obtain the fused positioning state of the current observation epoch.

8. A satellite-ground fusion positioning device, characterized in that, include: The first positioning and calculation module is used to perform RTK positioning and calculation based on the receiver observations, reference station observations and reference station coordinates to obtain RTK position and RTK accuracy information. The prior module is used to take the RTK position as the initial position for PPP positioning calculation, and to determine the prior accuracy information corresponding to the initial position based on the RTK position accuracy information. The second positioning calculation module is used to perform PPP positioning calculation based on the initial position, the prior accuracy information, the receiver observation value, the broadcast ephemeris and the BeiDou PPP-B2b satellite-based correction, to obtain the PPP position and PPP position accuracy information. The fusion module is used to perform position domain fusion calculation based on the RTK position, the PPP position, the RTK position accuracy information and the PPP position accuracy information to obtain the fused positioning state of the current observation epoch, and extrapolate the fused positioning state to obtain the prior state and prior accuracy information of the next observation epoch. The third positioning and calculation module is used to perform RTK positioning and calculation for the next observation epoch based on the prior state and the prior accuracy information, and to perform PPP positioning and calculation for the next observation epoch based on the prior state and the prior accuracy information when the RTK position of the next observation epoch cannot be obtained.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the satellite-ground fusion positioning method as described in any one of claims 1 to 7.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the satellite-ground fusion positioning method as described in any one of claims 1 to 7.

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