Ambiguity fixing method and device, equipment and medium

Abstract

The invention provides an ambiguity fixing method, device, equipment and medium, the method is applied to a target carrier, the target carrier communicates with a base station, the target carrier is provided with a multi-sensor odometer, and the method comprises the following steps: in the satellite positioning process of the target carrier, aiming at each double-difference satellite combination, according to an observation model of a pseudo range and a carrier phase, determining the ambiguity of each double-difference satellite combination; determining double-difference observation values when the target carrier and the base station simultaneously observe the double-difference satellite combination; determining an observation quality index of the target carrier to the double-difference satellite combination based on the double-difference observation value and the double-difference geometric distance between the target carrier and the double-difference satellite combination and between the base station and the double-difference satellite combination; and according to a sequence from large observation quality indexes to small observation quality indexes corresponding to the double-difference satellite combinations, sequentially rejecting the double-difference satellite combinations until a rejecting cut-off condition is met, and based on the double-difference observation values corresponding to the remaining double-difference satellite combinations when the rejecting cut-off condition is met, determining the ambiguity and the position of the target carrier. And the ambiguity fixing rate can be improved.

Description

Technical Field

[0001] This application relates to the field of satellite navigation technology, and more specifically, to a method, apparatus, device, and medium for fixing ambiguity. Background Technology

[0002] Emerging applications, such as autonomous vehicles and embodied intelligent robots, have created an urgent need for continuous, robust, and high-precision positional awareness capabilities for these vehicles in complex urban environments. Real-Time Kinematic (RTK) technology, a high-precision positioning method based on Global Navigation Satellite System (GNSS) carrier phase observations, has been widely applied in many fields. This technology can achieve centimeter-level positioning accuracy when GNSS observation quality is good.

[0003] However, in complex urban observation environments, building surfaces and vegetation canopies often obstruct and reflect some satellite signals, leading to multipath effects or non-direct signals. This type of interference significantly increases the measurement error of GNSS observations, especially pseudorange observations, thereby increasing the difficulty of fixing all ambiguities simultaneously, and consequently affecting the stability and reliability of the carrier's positioning accuracy. Summary of the Invention

[0004] In view of this, this application provides an ambiguity fixing method, apparatus, device and medium that combines triple-difference phase residuals and double-difference pseudorange residuals to jointly evaluate the observation quality. This helps to eliminate double-difference satellite combinations with poor observation quality, ensuring that double-difference satellite combinations with higher observation quality are used to estimate the carrier position, thereby improving the success rate of ambiguity fixing.

[0005] Specifically, this application is implemented through the following technical solution: According to a first aspect of this application, an ambiguity fixing method is provided, applied to a target carrier that communicates with a base station and is equipped with a multi-sensor odometer; the method includes: During the satellite positioning process of the target vehicle, for each double-difference satellite combination, based on the observation model of pseudorange and carrier phase, the double-difference observation value when the target vehicle and the reference station simultaneously observe the double-difference satellite combination is determined; the double-difference satellite combination includes reference satellites and non-reference satellites, and each double-difference satellite combination includes the same reference satellites but different non-reference satellites; Based on the double-difference observations and the double-difference geometric distances between the target vehicle, the reference station, and the double-difference satellite combination, the double-difference pseudorange residuals and double-difference phase residuals corresponding to the double-difference satellite combination are determined; the double-difference geometric distances are determined based on the predicted position of the vehicle obtained by the multi-sensor odometry. The double-difference phase residuals are subjected to inter-epoch differential processing to obtain the triple-difference phase residuals corresponding to the double-difference satellite combination; Based on the triple-difference phase residual and the double-difference pseudorange residual, the observation quality index of the target carrier for the double-difference satellite combination is determined; According to the observation quality index corresponding to each double-difference satellite combination in descending order, each double-difference satellite combination is eliminated in turn until the elimination cutoff condition is met. Based on the double-difference observation values ​​corresponding to the remaining double-difference satellite combinations when the elimination cutoff condition is met, the ambiguity and the position of the target carrier are determined.

[0006] In one optional implementation, the double-difference observations include double-difference pseudorange observations and double-difference phase observations; determining the double-difference pseudorange residuals and double-difference phase residuals corresponding to the double-difference satellite combination based on the double-difference observations and the double-difference geometric distances between the target carrier, the reference station, and the double-difference satellite combination includes: Based on the double-difference pseudorange observations and the double-difference geometric distances between the target carrier, the reference station, and the double-difference satellite combination, determine the double-difference pseudorange residuals corresponding to the double-difference satellite combination; Based on the double-difference phase observations and the double-difference geometric distance, the double-difference phase residuals corresponding to the double-difference satellite combination are determined.

[0007] In one optional implementation, the step of performing inter-epoch differential processing on the double-difference phase residuals to obtain the triple-difference phase residuals corresponding to the double-difference satellite combination includes: Differential processing is performed on the double-difference phase residual at the current epoch and the double-difference phase residual at the previous adjacent epoch to obtain the triple-difference phase residual corresponding to the double-difference satellite combination.

[0008] In one optional implementation, the step of performing inter-epoch differential processing on the double-difference phase residuals to obtain the triple-difference phase residuals corresponding to the double-difference satellite combination includes: Differential processing is performed on the double-difference phase residuals at the current epoch and the double-difference phase residuals at the target epoch to obtain the triple-difference phase residuals corresponding to the double-difference satellite combination; if the double-difference phase residuals change abruptly, the double-difference phase residuals at the target epoch are the double-difference phase residuals at the epoch where the change occurred; if the double-difference phase residuals do not change abruptly, the double-difference phase residuals at the target epoch are determined based on the double-difference phase residuals at historical epochs.

[0009] In one optional implementation, the elimination cutoff condition includes the number of remaining double-difference satellite combinations being less than a satellite combination number threshold, or the position of the target carrier determined based on the double-difference observations corresponding to the remaining double-difference satellite combinations being a correct fixed solution.

[0010] In one optional implementation, the step of sequentially eliminating each double-difference satellite combination according to its observation quality index from largest to smallest, until the elimination cutoff condition is met, includes: According to the observation quality index corresponding to each double-difference satellite combination in descending order, a preset number of double-difference satellite combinations are eliminated, and the number of remaining double-difference satellite combinations is compared with the threshold number of satellite combinations. If the number of remaining double-difference satellite combinations is less than the threshold number of satellite combinations, the elimination cutoff condition is determined to be met. If the number of remaining double-difference satellite combinations is greater than or equal to the threshold number of satellite combinations, based on the double-difference observations corresponding to the remaining double-difference satellite combinations, the ambiguity and the candidate position solution of the target carrier are determined. The candidate position solution is used as the real-time dynamic differential fixed solution. Based on the predicted position of the carrier, pseudo-fixed detection is performed on the real-time dynamic differential fixed solution to obtain the pseudo-fixed detection result. If the pseudo-fixed detection result indicates that the real-time dynamic differential fixed solution is correctly fixed, it is determined that the rejection cutoff condition is met; If the pseudo-fixed detection result indicates that the real-time dynamic differential fixed solution is pseudo-fixed, repeat the steps of eliminating a preset number of double-difference satellite combinations in descending order of the observation quality index corresponding to each double-difference satellite combination, and comparing the number of remaining double-difference satellite combinations with the satellite combination number threshold until the elimination cutoff condition is met.

[0011] In one optional implementation, the step of performing pseudo-fixed detection on the real-time dynamic differential fixed solution based on the carrier's predicted position to obtain pseudo-fixed detection results includes: Transform the predicted position of the carrier and the real-time dynamic differential fixed solution to the same coordinate system; Based on the carrier coordinates of the predicted carrier position in multiple directions after the coordinate system transformation, the first relative displacement of the predicted carrier position in multiple directions is determined, and based on the carrier coordinates of the real-time dynamic differential fixed solution in multiple directions after the coordinate system transformation, the second relative displacement of the real-time dynamic differential fixed solution in multiple directions is determined. Based on the first relative displacement and the second relative displacement, determine the relative displacement residual; The target statistic is determined based on the relative displacement residual and the variance that the relative displacement residual follows; Based on the degrees of freedom corresponding to the multiple directions, a statistical threshold corresponding to the multiple directions is determined. If the target statistic is less than the statistical threshold, the real-time dynamic difference fixed solution is determined to be correctly fixed; otherwise, it is determined to be pseudo-fixed.

[0012] According to a second aspect of this application, an ambiguity fixing device is provided, applied to a target carrier that communicates with a base station, the target carrier being equipped with a multi-sensor odometer, the device comprising: The dual-difference observation module is used to determine the dual-difference observation values ​​when the target vehicle and the reference station simultaneously observe the dual-difference satellite combination, based on the pseudorange and carrier phase observation model, for each dual-difference satellite combination during the satellite positioning process of the target vehicle; the dual-difference satellite combination includes reference satellites and non-reference satellites, and each dual-difference satellite combination includes the same reference satellites but different non-reference satellites; The residual determination module is used to determine the double-difference pseudorange residual and double-difference phase residual corresponding to the double-difference satellite combination based on the double-difference observations and the double-difference geometric distance between the target carrier, the reference station and the double-difference satellite combination; the double-difference geometric distance is determined based on the carrier's predicted position obtained by the multi-sensor odometry. The differential processing module is used to perform inter-epoch differential processing on the double-difference phase residuals to obtain the triple-difference phase residuals corresponding to the double-difference satellite combination; The quality assessment module is used to determine the observation quality index of the target carrier for the double-difference satellite combination based on the triple-difference phase residual and the double-difference pseudorange residual. The location determination module is used to sequentially eliminate each double-difference satellite combination in descending order of the observation quality index corresponding to each double-difference satellite combination until the elimination cutoff condition is met. Based on the double-difference observation values ​​corresponding to the remaining double-difference satellite combinations when the elimination cutoff condition is met, the ambiguity and the location of the target carrier are determined.

[0013] According to a third aspect of this application, a computer device is provided, 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 the steps of the ambiguity fixing method described in the first aspect above.

[0014] According to a fourth aspect of this application, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the ambiguity fixing method described in the first aspect above.

[0015] The ambiguity fixing method, apparatus, device, and medium provided in this application, for each double-difference satellite combination, determine the double-difference pseudorange residual and double-difference phase residual based on the double-difference observation value and double-difference geometric distance. Perform inter-epoch difference processing on the double-difference phase residual to obtain the triple-difference phase residual. Then, combine the double-difference pseudorange residual to determine the observation quality index. Sort according to the observation quality index corresponding to each double-difference satellite combination to identify and gradually eliminate satellite signals with poor observation quality, thereby selecting double-difference satellite combinations with high observation quality for carrier positioning, which helps to improve the ambiguity fixing rate.

[0016] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and are not intended to limit the technical solutions of this disclosure.

[0017] To make the above-mentioned objects, features and advantages of this disclosure more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating an application scenario in an exemplary embodiment of this application; Figure 2 This is a flowchart illustrating an exemplary embodiment of the present application of a method for fixing ambiguity; Figure 3 This is a schematic diagram illustrating a multi-sensor odometer according to an exemplary embodiment of this application; Figure 4 This is a schematic diagram illustrating an ambiguity fixing process according to an exemplary embodiment of this application; Figure 5a This is a schematic diagram of the RTK fixation rate under the traditional fuzziness fixation method; Figure 5b This is a schematic diagram illustrating the RTK fixation rate under the embodiments of this application; Figure 6 This is a schematic diagram illustrating a comparison of fixed solution coordinate deviations in an exemplary embodiment of this application; Figure 7This is a schematic diagram of an ambiguity fixing device shown in an exemplary embodiment of this application; Figure 8 This is a schematic diagram of the structure of a computer device shown in an exemplary embodiment of this application. Detailed Implementation

[0019] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0020] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0021] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0022] Research has found that in complex urban observation environments, building surfaces and vegetation canopies often obstruct and reflect some satellite signals, leading to multipath effects or non-direct signals. This type of interference significantly increases the measurement error of GNSS observations, especially pseudorange observations, thus increasing the difficulty of fixing all ambiguities simultaneously and affecting the positioning accuracy of the carrier.

[0023] Since RTK can achieve centimeter-level positioning accuracy by fixing only the ambiguity of satellite signals with good observation quality, in complex urban environments, timely identification and elimination of satellites with poor observation quality (hereinafter referred to as "gross error satellites") to determine the optimal ambiguity subset for partial ambiguity fixing is the key to ensuring the positioning accuracy and robustness of RTK.

[0024] Traditional methods for fixing partial ambiguity often employ the following approaches: characterizing the quality of the original observations in the observation domain based on information such as signal-to-noise ratio (SNR) and satellite elevation angle; or characterizing the accuracy of floating-point ambiguity in the ambiguity domain using information such as floating-point ambiguity variance and ambiguity precision factor to screen and eliminate gross error satellites and determine the optimal ambiguity subset. However, in complex urban observation environments, multipath signals or non-direct signals may have large SNRs and satellite elevation angles, and when the measurement error of GNSS observations is large, floating-point ambiguity variance and ambiguity precision factor cannot accurately characterize the quality of floating-point ambiguity. Hybrid satellite screening methods that integrate multiple indicators are also used, but their performance is poor on dynamic datasets collected in urban areas. Sky images captured by fisheye cameras can also be used to identify and eliminate gross error satellites; however, rain or dense fog can affect the quality of the sky images. Furthermore, receiver autonomous integrity monitoring (RIAM) is another approach, which allows for independent monitoring of the integrity of received signals without external information input. RAIM (Rapid Imaging Monitoring) technology has also been used to determine the optimal ambiguity subset. However, RAIM-based screening methods heavily rely on setting the false negative probability, which is difficult to determine accurately. Machine learning has also been introduced to assist in selecting the optimal ambiguity subset. While these methods can achieve non-line-of-sight (NLoS) recognition and ambiguity selection in complex environments, their model training may require a large and representative dataset, making them technically challenging to implement. Therefore, in complex urban environments, relying solely on degraded GNSS signals makes it difficult to accurately select the optimal ambiguity subset.

[0025] Based on the above research, this application provides an ambiguity fixation method. For each double-difference satellite combination, the double-difference pseudorange residual and double-difference phase residual are determined according to the double-difference observation values ​​and double-difference geometric distances. The double-difference phase residual is then subjected to inter-epoch difference processing to obtain a triple-difference phase residual. This residual is then combined with the double-difference pseudorange residual to determine the observation quality index. The observation quality indices of each double-difference satellite combination are used to rank the combinations, enabling the identification and gradual elimination of satellite signals with poor observation quality. This allows for the selection of satellite combinations with higher observation quality for carrier positioning, improving the ambiguity fixation rate. Compared to traditional parameters that often fail to accurately reflect observation quality in complex urban observation environments, this method has stronger applicability and robustness.

[0026] To facilitate understanding of this embodiment, a detailed description of the ambiguity fixing method disclosed in this application embodiment is provided first. The executor of the ambiguity fixing method provided in this application embodiment is generally an electronic device with a certain computing power. This electronic device can be a server, which can be an independent physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server providing basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud storage, big data, and artificial intelligence platforms. In some possible implementations, this ambiguity fixing method can be implemented by a processor calling computer-readable instructions stored in memory.

[0027] The following description, in conjunction with the accompanying drawings, illustrates a method for fixing ambiguity provided in an embodiment of this application.

[0028] Please see Figure 1 This is a schematic diagram illustrating an application scenario of an exemplary embodiment of this application. For example... Figure 1 As shown, the target carrier 10 communicates with the base station 20 via a radio, 4G / 5G / 6G network, or satellites (such as satellites 31, 32, 33, and 34). The target carrier 10 may include, but is not limited to, autonomous vehicles, embodied intelligent robots, etc. Satellites 31, 32, 33, and 34 may include one reference satellite and multiple non-reference satellites.

[0029] See Figure 2 The diagram shown is a flowchart illustrating an exemplary embodiment of this application, applied to methods such as... Figure 1 The target vehicle shown communicates with a base station via satellite and is equipped with a multi-sensor odometry (MSO). Figure 2 As shown in the figure, the ambiguity fixing method provided in this embodiment includes steps S201 to S205, wherein: S201: During the satellite positioning process of the target vehicle, for each double-difference satellite combination, based on the observation model of pseudorange and carrier phase, the double-difference observation value when the target vehicle and the reference station simultaneously observe the double-difference satellite combination is determined; the double-difference satellite combination includes reference satellites and non-reference satellites, and each double-difference satellite combination includes the same reference satellites and different non-reference satellites.

[0030] In this step, multiple double-difference satellite combinations can be defined to... Figure 1For example, if satellite 31 is the reference satellite and satellites 32, 33, and 34 are non-reference satellites, three double-difference satellite combinations can be defined: double-difference satellite combination 1 includes satellite 31 and satellite 32, double-difference satellite combination 2 includes satellite 31 and satellite 33, and double-difference satellite combination 3 includes satellite 31 and satellite 34.

[0031] For each double-difference satellite combination, the pseudorange and carrier phase observation values ​​when the target carrier and the reference station simultaneously observe the double-difference satellite combination can be determined according to the pseudorange and carrier phase observation model. The observation difference processing is performed on the pseudorange and carrier phase observation values ​​to obtain the double-difference observation value.

[0032] Specifically, in the satellite positioning process, the observation model for pseudorange and carrier phase can be represented by the following formula (1): (1) in, and These represent the receiver and satellite numbers, respectively. Set on the target carrier; Indicates satellite and receiver Pseudorange observations between (unit: meters); Indicates satellite and receiver Carrier phase observations between (unit: meters); Indicates clock difference; Satellite clock bias refers to the deviation between the atomic clock on a satellite and the GPS standard time. The receiver clock bias refers to the difference between the receiver's own clock and the satellite signal time. Indicates satellite to receiver The distance; Indicates ionospheric delay; Indicates spherical delay; Indicates satellite and receiver Hardware delay of the pseudorange between; Indicates satellite and receiver Carrier phase ambiguity between; Indicates satellite and receiver The uncalibrated delay of the carrier phase between them; Indicates the carrier wavelength; The observation noise representing the pseudorange; represents the observation noise of the carrier phase; c represents the speed of light in a vacuum.

[0033] Based on formula (1), the observations of a single common-view satellite are subtracted, i.e., inter-station single difference, which can eliminate satellite-related errors such as satellite orbit errors and satellite clock errors; the observations of two satellites tracked by the same receiver are subtracted, i.e., inter-satellite single difference, which can eliminate receiver-related errors such as pseudorange hardware delay and receiver clock errors; and the simultaneous execution of inter-station single difference and inter-satellite single difference, i.e., double difference, can eliminate most of the errors related to atmospheric delay, such as tropospheric and ionospheric delay errors. When the target carrier is close to the reference station (e.g., <5km), the errors related to atmospheric delay are almost completely eliminated. The double difference observations include double difference pseudorange observations and double difference phase observations, which can be determined by the following formula (2): (2) in, , , , These respectively represent the numbers of the user terminal (i.e., the target carrier), the base station, the reference satellite, and the non-reference satellite; and These represent inter-satellite single difference and inter-station single difference, respectively. This represents the double-difference pseudorange observations; Indicates the geometric distance between the two satellites and the ground; Indicates double-difference tropospheric delay; Indicates double-difference ionospheric delay; This indicates the noise of the double-difference pseudorange observation; P represents the pseudorange observation value. Indicates double-difference phase observations; Indicates the carrier wavelength; Indicates double-difference ambiguity; denoted by double-difference phase observation noise; L represents the phase observation value; the first formula in formula (2) is the double-difference pseudorange observation model, and the second formula is the double-difference phase observation model.

[0034] S202: Based on the double-difference observations and the double-difference geometric distance between the target vehicle, the reference station, and the double-difference satellite combination, determine the double-difference pseudorange residual and double-difference phase residual corresponding to the double-difference satellite combination; the double-difference geometric distance is determined based on the predicted position of the vehicle obtained by the multi-sensor odometry.

[0035] In this step, the double-difference satellite-to-ground geometric distance between the target carrier, the reference station, and the double-difference satellite combination can be determined based on the carrier's predicted position obtained through the multi-sensor odometry. Based on the double-difference observations and the double-difference geometric distance, the double-difference pseudorange residual and double-difference phase residual corresponding to the double-difference satellite combination can be determined.

[0036] In some possible implementations, the multi-sensor odometer includes a camera, an inertial measurement unit (i.e., an inertial navigation system), a lidar, a barometer, a magnetometer, and a global navigation satellite signal receiver (GNSS).

[0037] For example, see [link / reference] Figure 3 This is a schematic diagram illustrating a multi-sensor odometer, as shown in an exemplary embodiment of this application. Figure 3 As shown, the multi-sensor odometry system includes a camera, lidar, inertial navigation system (INS), barometer, magnetometer, GNSS chip, microcontroller unit (MCU), power supply, and onboard computer. These components are connected via serial cables. The GNSS chip receives satellite signals and calculates the time clock, triggering a second pulse signal, such as a square wave or spike signal, which is then sent to the MCU. Upon receiving the second pulse signal, the MCU triggers the camera, lidar, INS, barometer, and magnetometer to synchronously begin data acquisition, achieving synchronized data collection. Visual data acquired by the camera, 3D point cloud data acquired by the lidar, inertial navigation data acquired by the INS, GNSS observations acquired by the GNSS chip, barometric pressure data acquired by the barometer, and magnetic field strength data acquired by the magnetometer can be sent to the onboard computer for data output. For example, the onboard computer may include an RK3588S. The camera may include, for example, a monocular camera or a binocular camera.

[0038] In some possible implementations, the double-difference geometric distance is determined by the following steps: Based on visual data, inertial navigation data, 3D point cloud data, air pressure data, and magnetic field strength data collected by the multi-sensor odometry, the pose of the target carrier in the local world coordinate system and the pose variance corresponding to the pose are determined. The predicted position of the target carrier in the local world coordinate system is then predicted based on the pose of the target carrier in the local world coordinate system. The local world coordinate system is constructed with the initial position of the target carrier as the origin. Based on the GNSS observation data collected by the multi-sensor, a real-time dynamic differential positioning algorithm is used to determine the absolute position of the target carrier in the geocentric-geo-fixed coordinate system and the position variance corresponding to the absolute position of the carrier. Based on the target carrier's pose, pose variance, and predicted position in the local world coordinate system, as well as the target carrier's absolute position and position variance in the geocentric-earth-fixed coordinate system, coordinate system transformation is performed on the target carrier's predicted position in the local world coordinate system to obtain the target carrier's predicted position in the geocentric-earth-fixed coordinate system. The double-difference geometric distance is determined based on the predicted position of the target carrier in the geocentric-geocentric coordinate system, the reference station position in the geocentric-geocentric coordinate system, and the satellite positions of the reference satellite and the non-reference satellite in the satellite assembly in the geocentric-geocentric coordinate system.

[0039] In the above steps, visual data, inertial navigation data, 3D point cloud data, air pressure data, and magnetic field strength data collected by the multi-sensor odometry can be input into the MSO positioning algorithm to obtain the poses of the target carrier in the local-world coordinate system (w-frame) and the pose variance corresponding to each pose. Here, the obtained poses can be keyframe poses, and the keyframes include at least two frames with environmental feature association. The environmental feature association means that the distance between the carrier positions corresponding to each of the at least two frames is greater than a preset distance, and the at least two frames can observe the same object in the environment. The specific value of the preset distance can be determined according to the specific data filtering needs and is not limited here.

[0040] Optionally, the MSO includes a sliding window optimizer, which can predict the predicted positions (MSO predicted positions, MSOOPPs) of the target vehicle in the local world coordinate system based on the pose of the last keyframe in the sliding window optimizer and the inertial navigation observation data.

[0041] Based on GNSS observation data acquired through the multi-sensor system, and using RTK positioning based on an Extended Kalman Filter (EKF), the absolute position of the target vehicle in the Earth-Centered, Earth-Fixed (ECEF) coordinate system (e-frame) and the corresponding position variance can be determined. Based on the target vehicle's pose, pose variance, and predicted position in the local world coordinate system, as well as its absolute position and position variance in the ECEF coordinate system, a coordinate system transformation is performed on the predicted position of the target vehicle in the local world coordinate system to obtain its predicted position in the ECEF coordinate system. Based on the predicted position of the target vehicle in the ECEF coordinate system, the reference station's position in the ECEF coordinate system, and the positions of the reference and non-reference satellites in the satellite array in the ECEF coordinate system, the double-difference geometric distance is determined.

[0042] In this way, the double-difference geometric distance can be determined through the above method, which can then be used to help determine the double-difference pseudorange residual and double-difference phase residual, and further determine the observation quality index to eliminate double-difference satellite combinations, thus helping to improve the ambiguity fixation rate.

[0043] In some possible implementations, the step of performing coordinate system transformation on the predicted position of the target vehicle in the local world coordinate system based on the pose, pose variance, and predicted position of the target vehicle in the local world coordinate system, and the absolute position and position variance of the target vehicle in the geocentric-fixed coordinate system, to obtain the predicted position of the target vehicle in the geocentric-fixed coordinate system, includes: The pose and pose variance of the target carrier in the local world coordinate system are time-aligned with the absolute position and position variance of the target carrier in the geocentric coordinate system. The target carrier's absolute position and position variance in the geocentric-fixed coordinate system after time alignment are transformed to obtain the target carrier's absolute position and position variance in the navigation coordinate system; the navigation coordinate system is constructed with the first absolute position of the carrier as the origin. Based on the target vehicle's absolute position and position variance in the navigation coordinate system, and the target vehicle's pose and pose variance in the local world coordinate system, the transformation matrix between the navigation coordinate system and the local world coordinate system is determined. Based on the transformation matrix, the predicted position of the target vehicle in the local world coordinate system is transformed to obtain the predicted position of the target vehicle in the navigation coordinate system. Based on the coordinates of the origin of the navigation coordinate system in the geocentric-ground-fixed coordinate system, the predicted position of the target vehicle in the navigation coordinate system is recursively calculated to obtain the predicted position of the target vehicle in the geocentric-ground-fixed coordinate system.

[0044] In the above steps, the target vehicle's pose and pose variance in the local world coordinate system and its absolute position and position variance in the geocentric coordinate system can be time-aligned in the optimizer, and factor graph optimization can be performed to obtain the transformation matrix between the navigation coordinate system (n-system) and the local world coordinate system. Optionally, the navigation coordinate system is constructed with the first absolute position of the vehicle in the time-aligned absolute position-pose matching pair as the origin.

[0045] During factor graph optimization, the absolute position and position variance of the target vehicle in the geocentric-fixed coordinate system after time alignment are transformed to obtain the absolute position and position variance of the target vehicle in the navigation coordinate system. Based on the absolute position and position variance of the target vehicle in the navigation coordinate system and the pose and pose variance of the target vehicle in the local world coordinate system, the transformation matrix between the w-frame and the n-frame is determined. .

[0046] After obtaining the transformation matrix Subsequently, the predicted position of the target carrier in the w-system can be transformed to the n-system to obtain the predicted position of the target carrier in the n-system. Then, based on the coordinates of the origin of the navigation coordinate system in the geocentric coordinate system, the predicted position of the target carrier in the e-system is recursively deduced.

[0047] In this way, the predicted position of the target carrier in the geocentric-geo-fixed coordinate system can be obtained through the above method, which can then be used to construct motion constraints for double-difference geometric distance. By introducing the prediction information of high-precision multi-sensor odometer, the processing results can maintain continuity and robustness in dynamic and complex environments, which helps to improve the ambiguity fixation rate.

[0048] In some possible implementations, the method further includes: The absolute position of the target carrier in the Earth-centered Earth-fixed coordinate system is used as the real-time dynamic differential fixed solution. Based on the predicted position of the carrier, pseudo-fixed detection is performed on the real-time dynamic differential fixed solution. The time alignment process for the pose and pose variance of the target carrier in the local world coordinate system and the absolute position and position variance of the target carrier in the geocentric coordinate system includes: The pose and pose variance of the target carrier in the local world coordinate system are time-aligned with the absolute position and position variance of the target carrier identified as correctly fixed in the geocentric coordinate system.

[0049] In the above steps, a pseudo-fixed detection can be performed on the absolute position of the target carrier in the geocentric-geocentric coordinate system. The correctly fixed absolute positions of the target carrier in the geocentric-geocentric coordinate system are then selected. During time alignment, the correctly fixed absolute positions and position variances of the target carrier in the geocentric-geocentric coordinate system are time-aligned with the pose and pose variance of the target carrier in the local world coordinate system. This helps ensure the accuracy and effectiveness of the time alignment process and reduces the interference of pseudo-fixed solutions on time alignment.

[0050] False fixation is highly susceptible to occur in fixed ambiguity results. Traditional methods for detecting false fixation often employ the following approaches: setting a threshold for the coordinate difference between adjacent epochs to identify false fixation epochs; however, this method requires the coordinates of the previous epoch to be correct and the time difference between epochs to be relatively small, making it difficult to implement; using Doppler velocity measurements to recursively deduce the approximate position of the carrier at the current epoch, and determining whether the current epoch is false fixation by judging whether the deviation between the approximate position and the fixed coordinates exceeds a threshold; however, the accuracy of Doppler observations is poor in complex observation environments, limiting the practical application of this method; GNSS and inertial navigation, cameras, and lidar... While traditional methods employ a combination of sensors and mechanical arrangement based on inertial navigation data to recursively estimate the approximate position of a carrier at the current epoch, pseudo-fixed detection is achieved by determining whether the deviation between this approximate position and the fixed coordinates of the current epoch exceeds a threshold. However, when GNSS observation quality degrades significantly, the accuracy of the recursive position estimate from inertial navigation also degrades considerably. Machine learning-based methods, using labeled data, establish and train a mapping model between real pseudo-fixed coordinates / ambiguities and data such as geometric accuracy factors, RTK positioning residuals, satellite elevation angles, and signal-to-noise ratios to predict pseudo-fixed epochs. However, training this model requires a large and representative dataset, making its implementation technically challenging. Therefore, traditional pseudo-fixed detection algorithms struggle to adapt to urban observation environments with poor positioning results.

[0051] In some possible implementations, the step of performing pseudo-fixed detection on the real-time dynamic differential fixed solution based on the carrier's predicted position to obtain pseudo-fixed detection results includes: Transform the predicted position of the carrier and the real-time dynamic differential fixed solution to the same coordinate system; Based on the carrier coordinates of the predicted carrier position in multiple directions after the coordinate system transformation, the first relative displacement of the predicted carrier position in multiple directions is determined, and based on the carrier coordinates of the real-time dynamic differential fixed solution in multiple directions after the coordinate system transformation, the second relative displacement of the real-time dynamic differential fixed solution in multiple directions is determined. Based on the first relative displacement and the second relative displacement, determine the relative displacement residual; The target statistic is determined based on the relative displacement residual and the variance that the relative displacement residual follows; Based on the degrees of freedom corresponding to the multiple directions, a statistical threshold corresponding to the multiple directions is determined. If the target statistic is less than the statistical threshold, the real-time dynamic difference fixed solution is determined to be correctly fixed; otherwise, it is determined to be pseudo-fixed.

[0052] In the above steps, the predicted position of the carrier and the real-time dynamic differential (RTK) fixed solution can be transformed to the same coordinate system, for example, both to the n-system. For multiple directions, such as the east (E), north (N), and up (U) directions, the first relative displacement of the predicted position of the carrier in multiple directions is determined based on the carrier coordinates of the predicted position of the carrier in multiple directions after the coordinate system transformation.

[0053] For example, the first relative displacement can be determined by the following formula (3): (3) in, Indicates the first relative displacement; This represents the carrier coordinates in the E direction of the predicted carrier position at the k-th epoch; This represents the carrier coordinates in the E direction of the predicted carrier position at the (k-1)th epoch. This represents the carrier coordinates in the N direction of the predicted carrier position at the k-th epoch; This represents the carrier coordinates in the N direction of the predicted carrier position in the (k-1)th epoch; This represents the carrier coordinates in the U direction of the predicted carrier position at the k-th epoch; This represents the carrier coordinates in the N direction of the predicted carrier position in the (k-1)th epoch.

[0054] Based on the carrier coordinates in multiple directions of the real-time dynamic differential fixed solution after coordinate system transformation, the second relative displacement of the real-time dynamic differential fixed solution in multiple directions is determined.

[0055] For example, the second relative displacement can be determined by the following formula (4): (4) in, Indicates the second relative displacement; This represents the carrier coordinates in the E direction for the k-th fixed RTK solution; This represents the carrier coordinates in the E direction of the fixed RTK solution in the (k-1)th epoch. This represents the carrier coordinates in the N direction of the fixed RTK solution at the k-th epoch; This represents the carrier coordinates in the N direction of the fixed RTK solution in the (k-1)th epoch; This represents the carrier coordinates in the U direction of the fixed RTK solution in the k-th epoch; This represents the carrier coordinates in the N direction of the fixed RTK solution in the (k-1)th epoch.

[0056] Based on the first relative displacement and the second relative displacement, the relative displacement residual is determined. Specifically, the difference between the first relative displacement and the second relative displacement can be determined as the relative displacement residual.

[0057] For example, the relative displacement residual can be determined by the following formula (5): (5) in, Represents the relative displacement residual; Indicates the first relative displacement; This indicates the second relative displacement.

[0058] The target statistic is determined based on the relative displacement residual and the variance that the relative displacement residual follows.

[0059] For example, in formula (5) Follows the variance If the distribution is normal with a mean of 0, then the chi-square test statistic can be determined by the following formula (6): (6) in, Indicates the target statistic; Represents the relative displacement residual; express The variance of obedience.

[0060] Then, the confidence / significance level can be set to a value between 0.001 and 0.99. Based on the degrees of freedom corresponding to the multiple directions, the threshold values ​​for the statistics corresponding to the multiple directions can be obtained by consulting the threshold table for the three-degree-of-freedom chi-square test. The threshold table for the three-degree-of-freedom chi-square test is used to indicate the mapping relationship between degrees of freedom and statistical threshold values. For example, it can be found that... Corresponding statistical threshold .

[0061] If the target statistic is less than the statistic threshold, the real-time dynamic difference fixed solution is determined to be correctly fixed; if the target statistic is greater than or equal to the statistic threshold, the real-time dynamic difference fixed solution is determined to be pseudo fixed.

[0062] In this way, the relative displacement between epochs obtained by estimating the predicted position of the carrier from the multi-sensor odometer is used to assist in the detection of pseudo-fixed epochs in the position domain, thereby improving the reliability of RTK fixed coordinates. Since the determination of the predicted position of the carrier does not require GNSS observations, the impact of GNSS observations on the accuracy of the odometer predicted position can be minimized when the amount of GNSS observations is severely degraded. At the same time, the embodiments of this disclosure give full play to the advantage of the high accuracy of the multi-sensor odometer in relative displacement estimation, so as to achieve effective discrimination of pseudo-fixed epochs, thereby significantly improving the correct fixation rate of ambiguity, as well as the accuracy and reliability of the fixed solution.

[0063] In some possible implementations, the double-difference observations include double-difference pseudorange observations and double-difference phase observations; determining the double-difference pseudorange residuals and double-difference phase residuals corresponding to the double-difference satellite combination based on the double-difference observations and the double-difference geometric distances between the target carrier, the reference station, and the double-difference satellite combination includes: Based on the double-difference pseudorange observations and the double-difference geometric distances between the target carrier, the reference station, and the double-difference satellite combination, determine the double-difference pseudorange residuals corresponding to the double-difference satellite combination; Based on the double-difference phase observations and the double-difference geometric distance, the double-difference phase residuals corresponding to the double-difference satellite combination are determined.

[0064] In the above steps, the difference between the double-difference pseudorange observation and the double-difference geometric distance can be determined as the double-difference pseudorange residual corresponding to the double-difference satellite combination.

[0065] For example, the double-difference pseudorange residual can be determined by the following formula (7): (7) in, , , , These respectively represent the numbers of the user terminal (i.e., the target carrier), the base station, the reference satellite, and the non-reference satellite; This represents the pseudo-range residual of the double difference; This represents the double-difference pseudorange observations; This represents the double difference geometric distance.

[0066] The difference between the double-difference phase observation and the double-difference geometric distance can be determined as the double-difference phase residual corresponding to the double-difference satellite combination.

[0067] For example, the double-difference phase residual can be determined by the following formula (8): (8) in, , , , These respectively represent the numbers of the user terminal (i.e., the target carrier), the base station, the reference satellite, and the non-reference satellite; Indicates the double-difference phase residual; Indicates double-difference phase observations; This represents the double difference geometric distance.

[0068] In this way, the double-difference pseudorange residual and double-difference phase residual corresponding to the double-difference satellite combination can be determined through the above method, laying the foundation for the construction of subsequent observation quality indicators.

[0069] S203: Perform inter-epoch differential processing on the double-difference phase residuals to obtain the triple-difference phase residuals corresponding to the double-difference satellite combination.

[0070] In this step, the double-difference phase residuals can be processed by inter-epoch difference to obtain the triple-difference phase residuals corresponding to the double-difference satellite combination, thereby eliminating ambiguity terms.

[0071] Specifically, the difference between adjacent epochs or across epochs of the double-difference phase residual can be performed.

[0072] In some possible implementations, the step of performing inter-epoch differential processing on the double-difference phase residuals to obtain the triple-difference phase residuals corresponding to the double-difference satellite combination includes: Differential processing is performed on the double-difference phase residual at the current epoch and the double-difference phase residual at the previous adjacent epoch to obtain the triple-difference phase residual corresponding to the double-difference satellite combination.

[0073] Specifically, the difference between the double-difference phase residual at the current epoch and the double-difference phase residual at the previous adjacent epoch can be determined as the triple-difference phase residual.

[0074] For example, the three-difference phase residuals after differencing between adjacent epochs can be determined by the following formula (9): (9) in, , , , These respectively represent the numbers of the user terminal (i.e., the target carrier), the base station, the reference satellite, and the non-reference satellite; This represents the three-difference phase residuals after differencing between adjacent epochs; This represents the double-difference phase residual at the t-th epoch; This represents the double-difference phase residual at the (t-1)th epoch.

[0075] In this way, the three-difference phase residuals can be determined through the above method, laying the foundation for the construction of subsequent observation quality indicators.

[0076] In some other possible implementations, the step of performing inter-epoch differential processing on the double-difference phase residuals to obtain the triple-difference phase residuals corresponding to the double-difference satellite combination includes: Differential processing is performed on the double-difference phase residuals at the current epoch and the double-difference phase residuals at the target epoch to obtain the triple-difference phase residuals corresponding to the double-difference satellite combination; if the double-difference phase residuals change abruptly, the double-difference phase residuals at the target epoch are the double-difference phase residuals at the epoch where the change occurred; if the double-difference phase residuals do not change abruptly, the double-difference phase residuals at the target epoch are determined based on the double-difference phase residuals at historical epochs.

[0077] Specifically, the difference between the double-difference phase residual at the current epoch and the double-difference phase residual at the target epoch can be determined as the triple-difference phase residual.

[0078] For example, the three-difference phase residuals after cross-epoch difference can be determined by the following formula (10): (10) in, , , , These respectively represent the numbers of the user terminal (i.e., the target carrier), the base station, the reference satellite, and the non-reference satellite; This represents the three-difference phase residuals after cross-epoch difference; This represents the double-difference phase residual at the t-th epoch; Indicates the first Double-difference phase residuals at each epoch (i.e., the target epoch).

[0079] Due to the existence of ambiguity, if the phase observations of the double-difference satellite combination have cycle slips, the corresponding double-difference phase residuals will also change. In the case of a change in the double-difference phase residuals, the double-difference phase residual at the target epoch is the double-difference phase residual at the epoch where the change occurred. If the double-difference phase residuals do not change, the double-difference phase residual at the target epoch is determined based on the double-difference phase residuals at historical epochs. Optionally, the double-difference phase residual at the target epoch can have the same double-difference ambiguity as the double-difference phase residual at the current epoch. The minimum / mean / median / maximum value of the double-difference phase residuals at all or part of the historical epochs. When selecting a portion of the historical epochs, a certain number of epochs before the current epoch can be selected, such as 100 epochs before the current epoch.

[0080] In this way, the three-difference phase residuals can be determined through the above method, laying the foundation for the construction of subsequent observation quality indicators.

[0081] S204: Based on the triple-difference phase residual and the double-difference pseudorange residual, determine the observation quality index of the target carrier for the double-difference satellite combination.

[0082] In this step, the triple-difference phase residual and the double-difference pseudorange residual corresponding to the double-difference satellite combination can be weighted and summed to obtain the observation quality index of the target carrier for the double-difference satellite combination.

[0083] For example, the observation quality index can be determined by the following formula (11): (11) in, , , , These respectively represent the numbers of the user terminal (i.e., the target carrier), the base station, the reference satellite, and the non-reference satellite; Indicates the observation quality index; Indicates the three-difference phase residual; express Weighting coefficients; This represents the pseudo-range residual of the double difference; express Weighting coefficients; This represents the three-difference phase residuals after differencing between adjacent epochs; This represents the three-difference phase residuals after cross-epoch difference.

[0084] In this way, the above methods can be used to determine the indicators that characterize the quality of GNSS observations when the target carrier observes a combination of dual-difference satellites, laying the foundation for subsequent satellite selection.

[0085] S205: According to the observation quality index corresponding to each double-difference satellite combination in descending order, eliminate each double-difference satellite combination in turn until the elimination cutoff condition is met. Based on the double-difference observation values ​​corresponding to the remaining double-difference satellite combinations when the elimination cutoff condition is met, determine the ambiguity and the position of the target carrier.

[0086] In this step, for all double-difference satellite combinations at the current epoch, each double-difference satellite combination is eliminated in descending order of its corresponding observation quality index until the elimination cutoff condition is met.

[0087] In some possible implementations, the elimination cutoff condition includes the number of remaining double-difference satellite combinations being less than a satellite combination number threshold, or the position of the target carrier determined based on the double-difference observations corresponding to the remaining double-difference satellite combinations being a correct fixed solution.

[0088] In some possible implementations, the step of sequentially eliminating each double-difference satellite combination in descending order of its observation quality index, until the elimination cutoff condition is met, includes: According to the observation quality index corresponding to each double-difference satellite combination in descending order, a preset number of double-difference satellite combinations are eliminated, and the number of remaining double-difference satellite combinations is compared with the threshold number of satellite combinations. If the number of remaining double-difference satellite combinations is less than the threshold number of satellite combinations, the elimination cutoff condition is determined to be met. If the number of remaining double-difference satellite combinations is greater than or equal to the threshold number of satellite combinations, based on the double-difference observations corresponding to the remaining double-difference satellite combinations, the ambiguity and the candidate position solution of the target carrier are determined. The candidate position solution is used as the real-time dynamic differential fixed solution. Based on the predicted position of the carrier, pseudo-fixed detection is performed on the real-time dynamic differential fixed solution to obtain the pseudo-fixed detection result. If the pseudo-fixed detection result indicates that the real-time dynamic differential fixed solution is correctly fixed, it is determined that the rejection cutoff condition is met; If the pseudo-fixed detection result indicates that the real-time dynamic differential fixed solution is pseudo-fixed, repeat the steps of eliminating a preset number of double-difference satellite combinations in descending order of the observation quality index corresponding to each double-difference satellite combination, and comparing the number of remaining double-difference satellite combinations with the satellite combination number threshold until the elimination cutoff condition is met.

[0089] In the above steps, according to the order of observation quality index corresponding to each of the dual-difference satellite combinations from largest to smallest, a preset number of dual-difference satellite combinations are eliminated, and the number of remaining dual-difference satellite combinations is compared with the satellite combination number threshold. The specific values ​​of the preset number and the satellite combination number threshold can be determined according to the actual ambiguity fixing needs, and are not limited here. For example, the preset number can be 2, and the satellite combination number threshold can be 5.

[0090] If the number of remaining double-difference satellite combinations is less than the threshold number of satellite combinations, the elimination cutoff condition is determined to be met. Then, the floating-point solution obtained by resolving the ambiguity and target carrier position based on the double-difference observation values ​​corresponding to the remaining double-difference satellite combinations after the previous elimination of double-difference satellite combinations when the elimination cutoff condition is met can be used to determine the position of the target carrier. For example, the floating-point double-difference ambiguity can be determined by using a Kalman filter based on the double-difference observation values ​​corresponding to the remaining double-difference satellite combinations after the previous elimination of double-difference satellite combinations when the elimination cutoff condition is met, and the determined floating-point double-difference ambiguity can replace the double-difference ambiguity in the double-difference phase observation model in formula (2). (Redetermine the dual-difference satellite-to-ground geometric distance) The floating-point position (i.e., floating-point solution) of the target carrier is determined from the redefined dual-difference satellite-to-ground geometric distance.

[0091] If the number of remaining double-difference satellite combinations is greater than or equal to the threshold number of satellite combinations, based on the double-difference observations corresponding to the remaining double-difference satellite combinations, a fixed ambiguity solution and its corresponding candidate position solution for the target carrier are determined. The candidate position solution is used as a real-time dynamic differential fixed solution. Based on the predicted position of the carrier, pseudo-fixed detection is performed on the real-time dynamic differential fixed solution to obtain the pseudo-fixed detection result.

[0092] Here, the process of using the candidate position solution as the real-time dynamic differential fixed solution and performing pseudo-fixed detection on the real-time dynamic differential fixed solution based on the predicted position of the carrier is similar to the process of using the absolute position of the target carrier in the geocentric coordinate system as the real-time dynamic differential fixed solution and performing pseudo-fixed detection on the real-time dynamic differential fixed solution based on the predicted position of the carrier during the aforementioned time alignment processing. For a detailed description, please refer to the above embodiments, which will not be repeated here.

[0093] If the pseudo-fixed detection result indicates that the real-time dynamic differential fixed solution is correctly fixed, then the elimination cutoff condition is satisfied. Optionally, the candidate position solution determined to be the correct fixed solution can be determined as the final position of the target carrier.

[0094] If the pseudo-fixed detection result indicates that the real-time dynamic differential fixed solution is pseudo-fixed, repeat the steps of eliminating a preset number of double-difference satellite combinations in descending order of the observation quality index corresponding to each double-difference satellite combination, and comparing the number of remaining double-difference satellite combinations with the satellite combination number threshold until the elimination cutoff condition is met.

[0095] In this way, by arranging the observation quality indices corresponding to all double-difference satellite combinations in the current epoch in descending order and iteratively deleting the double-difference satellite combinations ranked at the top, the accurate determination of the ambiguity subset can be effectively achieved. Compared with the traditional method, the embodiments of this disclosure rely on a more accurate observation quality index as a GNSS observation quality indicator, which can quickly and accurately determine the double-difference satellite combinations with better observation quality. Furthermore, the iterative deletion step can attempt to fix the ambiguity multiple times, thereby improving the fixation rate of RTK.

[0096] To illustrate the process of ambiguity fixing more clearly, see [link to documentation]. Figure 4 This is a schematic diagram illustrating an ambiguity fixing process, as shown in an exemplary embodiment of this application. Figure 4 As shown, a multi-sensor odometry system, comprising lidar, inertial navigation, camera, barometer, and magnetometer, can determine the keyframe pose, pose variance, and predicted position of the target vehicle in the w-frame. Furthermore, GNSS observation data can be used to determine the absolute position and position variance of the target vehicle in the e-frame. The optimizer can perform time alignment processing on the target vehicle's pose and pose variance in the w-frame and its absolute position and position variance in the e-frame, followed by factor graph optimization to obtain the transformation matrix between the navigation coordinate system (n-frame) and the w-frame. According to the transformation matrix The predicted carrier position under the w-system is transformed to the n-system, and finally transformed to the e-system, thereby determining the double-difference geometric distance based on the predicted carrier position. Based on the double-difference geometric distance, combined with the double-difference pseudorange observations and double-difference phase observations, the observation quality index of the target carrier for the double-difference satellite combination is determined. A preset number of double-difference satellite combinations are eliminated in descending order of their observation quality indices, and the remaining number of double-difference satellite combinations is compared with a satellite combination number threshold (5 in this example). If the remaining number of double-difference satellite combinations is less than the satellite combination number threshold, the elimination cutoff condition is met, and a floating-point solution is obtained. If the remaining number of double-difference satellite combinations is greater than or equal to the satellite combination number threshold, based on the double-difference observations corresponding to the remaining double-difference satellite combinations, a fixed solution for the ambiguity and the corresponding candidate position solution of the target carrier are determined using RTK. The candidate position solution is used as a real-time dynamic differential fixed solution. Based on the predicted carrier position, pseudo-fixed detection is performed on the real-time dynamic differential fixed solution to obtain the pseudo-fixed detection result. If the pseudo-fixed detection result indicates that the real-time dynamic differential fixed solution is correctly fixed, the elimination cutoff condition is satisfied, and a fixed solution is obtained. If the pseudo-fixed detection result indicates that the real-time dynamic differential fixed solution is pseudo-fixed, the process of eliminating a preset number of double-difference satellite combinations in descending order of the observation quality index corresponding to each of the double-difference satellite combinations, and comparing the number of remaining double-difference satellite combinations with the satellite combination number threshold, is repeated until the elimination cutoff condition is satisfied. Specific steps are described in the aforementioned embodiments and will not be repeated here.

[0097] The embodiments disclosed herein can significantly improve the fixation rate and positioning accuracy of RTK in complex environments, and are especially suitable for application scenarios such as urban canyons, obstructed environments, or severe multipath interference.

[0098] To more clearly demonstrate the effect of fixed blur, please refer to the example provided. Figure 5a , Figure 5b and Figure 6 , Figure 5a This is a schematic diagram of the RTK fixation rate under the traditional fuzziness fixation method. Figure 5b This is a schematic diagram of the RTK fixed rate under the embodiment of this application. In this example, during data processing, the weighting coefficient a of the three-difference phase residual in formula (11) is 1.0, and the weighting coefficient b of the double-difference pseudorange residual is 100 (normally, the measurement error of pseudorange is about 100 times the measurement error of carrier phase). When eliminating double-difference satellite combinations, three double-difference satellite combinations are eliminated each time. Figure 5aThe diagram illustrates the carrier trajectory, fixed solution, and floating-point solution under real-world satellite signal reception conditions in an urban setting, employing a traditional method of partial ambiguity fixation based on floating-point ambiguity variance. The horizontal axis represents the carrier coordinates in the E direction, and the vertical axis represents the carrier coordinates in the N direction. • represents the fixed solution under the traditional ambiguity fixation method, and △ represents the floating-point solution under the traditional ambiguity fixation method. It can be understood that the direction indicated by the arrow represents the carrier's movement direction. The RTK fixation rate under the traditional ambiguity fixation method is 91.5%. Figure 5b The diagram illustrates the carrier trajectory, fixed solution, and floating-point solution under real-world satellite signal reception conditions in an urban setting, using the ambiguity fixing method described in this embodiment. The horizontal axis represents the carrier coordinates in the E direction, and the vertical axis represents the carrier coordinates in the N direction. • represents the fixed solution under the ambiguity fixing method of this embodiment, and △ represents the floating-point solution under the ambiguity fixing method of this embodiment. It can be understood that the direction indicated by the arrow represents the carrier trajectory. The RTK fixation rate under the ambiguity fixing method of this embodiment is 97.6%. Compared with traditional ambiguity fixing methods, the RTK fixation rate of this embodiment is higher.

[0099] Figure 6 This is a schematic diagram illustrating a comparison of fixed solution coordinate deviations, as shown in an exemplary embodiment of this application. Figure 6 The diagram illustrates the coordinate deviations of fixed solutions under real-world satellite signal reception conditions in an urban setting, comparing the traditional ambiguity fixing method with the ambiguity fixing method of this embodiment. The horizontal axis represents time, and the vertical axis represents the carrier coordinates in the E, N, and U directions, respectively. × indicates the coordinate deviation of fixed solutions under the traditional ambiguity fixing method, and • indicates the coordinate deviation of fixed solutions under the ambiguity fixing method of this embodiment. The RTK fixed solution coordinate sequence of the traditional ambiguity fixing method contains many pseudo-fixed solutions, while the RTK fixed solution coordinate sequence of the ambiguity fixing method of this embodiment has almost no pseudo-fixed solutions.

[0100] By adopting the method of the present disclosure, not only can the RTK fixation rate be effectively improved, but the accuracy of the fixed solution coordinates can also be significantly improved.

[0101] The ambiguity fixing method provided in this application, for each double-difference satellite combination, determines the double-difference pseudorange residual and double-difference phase residual based on the double-difference observation value and double-difference geometric distance. The double-difference phase residual is subjected to inter-epoch difference processing to obtain the triple-difference phase residual. Then, the observation quality index is determined by combining the double-difference pseudorange residual. The observation quality index corresponding to each double-difference satellite combination is sorted to identify and gradually eliminate satellite signals with poor observation quality, thereby selecting double-difference satellite combinations with high observation quality for carrier positioning, which helps to improve the ambiguity fixing rate.

[0102] Corresponding to the embodiments of the aforementioned ambiguity fixing method, this application also provides embodiments of ambiguity fixing devices.

[0103] Please see Figure 7 This is a schematic diagram illustrating an ambiguity fixing device according to an exemplary embodiment of this application. The ambiguity fixing device provided in this embodiment is applied to the aforementioned target carrier, which communicates with a base station. The target carrier is equipped with a multi-sensor odometer. The ambiguity fixing device can be part of the target carrier, and modules in the ambiguity fixing device can be coupled with corresponding functional components in the target carrier to jointly achieve the same function. Figure 7 As shown in the figure, the ambiguity fixing device 700 provided in this application embodiment includes: The dual-difference observation module 701 is used to determine, during the satellite positioning process of the target vehicle, the dual-difference observation value when the target vehicle and the reference station simultaneously observe the dual-difference satellite combination, based on the observation model of pseudorange and carrier phase, for each dual-difference satellite combination; the dual-difference satellite combination includes reference satellites and non-reference satellites, and each dual-difference satellite combination includes the same reference satellites but different non-reference satellites; The residual determination module 702 is used to determine the double-difference pseudorange residual and double-difference phase residual corresponding to the double-difference satellite combination based on the double-difference observations and the double-difference geometric distance between the target carrier, the reference station and the double-difference satellite combination; the double-difference geometric distance is determined based on the carrier's predicted position obtained by the multi-sensor odometry. The differential processing module 703 is used to perform inter-epoch differential processing on the double-difference phase residual to obtain the triple-difference phase residual corresponding to the double-difference satellite combination; The quality assessment module 704 is used to determine the observation quality index of the target carrier for the double-difference satellite combination based on the triple-difference phase residual and the double-difference pseudorange residual; The location determination module 705 is used to sequentially eliminate each double-difference satellite combination in descending order of the observation quality index corresponding to each double-difference satellite combination until the elimination cutoff condition is met. Based on the double-difference observation values ​​corresponding to the remaining double-difference satellite combinations when the elimination cutoff condition is met, the ambiguity and the location of the target carrier are determined.

[0104] In some possible implementations, the double-difference observations include double-difference pseudorange observations and double-difference phase observations; the residual determination module 702 is specifically used for: Based on the double-difference pseudorange observations and the double-difference geometric distances between the target carrier, the reference station, and the double-difference satellite combination, determine the double-difference pseudorange residuals corresponding to the double-difference satellite combination; Based on the double-difference phase observations and the double-difference geometric distance, the double-difference phase residuals corresponding to the double-difference satellite combination are determined.

[0105] In some possible implementations, the differential processing module 703 is specifically used for: Differential processing is performed on the double-difference phase residual at the current epoch and the double-difference phase residual at the previous adjacent epoch to obtain the triple-difference phase residual corresponding to the double-difference satellite combination.

[0106] In some possible implementations, the differential processing module 703 is specifically used for: Differential processing is performed on the double-difference phase residuals at the current epoch and the double-difference phase residuals at the target epoch to obtain the triple-difference phase residuals corresponding to the double-difference satellite combination; if the double-difference phase residuals change abruptly, the double-difference phase residuals at the target epoch are the double-difference phase residuals at the epoch where the change occurred; if the double-difference phase residuals do not change abruptly, the double-difference phase residuals at the target epoch are determined based on the double-difference phase residuals at historical epochs.

[0107] In some possible implementations, the elimination cutoff condition includes the number of remaining double-difference satellite combinations being less than a satellite combination number threshold, or the target carrier position of the target carrier determined based on the double-difference observations corresponding to the remaining double-difference satellite combinations being a correct fixed solution.

[0108] In some possible implementations, the location determination module 705, when used to sequentially eliminate each double-difference satellite combination in descending order of the observation quality index corresponding to each double-difference satellite combination until the elimination cutoff condition is met, specifically performs the following: According to the observation quality index corresponding to each double-difference satellite combination in descending order, a preset number of double-difference satellite combinations are eliminated, and the number of remaining double-difference satellite combinations is compared with the threshold number of satellite combinations. If the number of remaining double-difference satellite combinations is less than the threshold number of satellite combinations, the elimination cutoff condition is determined to be met. If the number of remaining double-difference satellite combinations is greater than or equal to the threshold number of satellite combinations, based on the double-difference observations corresponding to the remaining double-difference satellite combinations, the ambiguity and the candidate position solution of the target carrier are determined. The candidate position solution is used as the real-time dynamic differential fixed solution. Based on the predicted position of the carrier, pseudo-fixed detection is performed on the real-time dynamic differential fixed solution to obtain the pseudo-fixed detection result. If the pseudo-fixed detection result indicates that the real-time dynamic differential fixed solution is correctly fixed, it is determined that the rejection cutoff condition is met; If the pseudo-fixed detection result indicates that the real-time dynamic differential fixed solution is pseudo-fixed, repeat the steps of eliminating a preset number of double-difference satellite combinations in descending order of the observation quality index corresponding to each double-difference satellite combination, and comparing the number of remaining double-difference satellite combinations with the satellite combination number threshold until the elimination cutoff condition is met.

[0109] In some possible implementations, when the position determination module 705 performs pseudo-fixed detection on the real-time dynamic differential fixed solution based on the carrier's predicted position to obtain the pseudo-fixed detection result, it is specifically used for: Transform the predicted position of the carrier and the real-time dynamic differential fixed solution to the same coordinate system; Based on the carrier coordinates of the predicted carrier position in multiple directions after the coordinate system transformation, the first relative displacement of the predicted carrier position in multiple directions is determined, and based on the carrier coordinates of the real-time dynamic differential fixed solution in multiple directions after the coordinate system transformation, the second relative displacement of the real-time dynamic differential fixed solution in multiple directions is determined. Based on the first relative displacement and the second relative displacement, determine the relative displacement residual; The target statistic is determined based on the relative displacement residual and the variance that the relative displacement residual follows; Based on the degrees of freedom corresponding to the multiple directions, a statistical threshold corresponding to the multiple directions is determined. If the target statistic is less than the statistical threshold, the real-time dynamic difference fixed solution is determined to be correctly fixed; otherwise, it is determined to be pseudo-fixed.

[0110] The specific implementation process of the functions and roles of each unit in the above device can be found in the implementation process of the corresponding steps in the above method, and will not be repeated here.

[0111] For the device embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and 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 application according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0112] Based on the same technical concept, this application also provides a computer device 800, referring to... Figure 8 The diagram shown is a schematic representation of the structure of a computer device according to an exemplary embodiment of this application, comprising: The processor 810, memory 820, and bus 830 are included. The memory 820 is used to store execution instructions and includes main memory 821 and external memory 822. The main memory 821, also known as internal memory, is used to temporarily store the operation data in the processor 810 and the data exchanged with external memory 822 such as hard disk. The processor 810 exchanges data with external memory 822 through main memory 821.

[0113] In this embodiment, the memory 820 is specifically used to store application code that executes the solution of this application, and its execution is controlled by the processor 810. That is, when the electronic device 800 is running, the processor 810 communicates with the memory 820 through the bus 830, or the processor 810 communicates with the memory 820 through other means, so that the processor 810 executes the application code stored in the memory 820, and then executes the steps of the ambiguity fixing method described in any of the foregoing embodiments.

[0114] The memory 820 may be, but is not limited to, random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.

[0115] Processor 810 may be an integrated circuit chip with signal processing capabilities. The aforementioned processor can be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it can also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this invention. The general-purpose processor can be a microprocessor or any conventional processor.

[0116] It is understood that the structures illustrated in the embodiments of this application do not constitute a specific limitation on the electronic device 800. In other embodiments of this application, the electronic device 800 may include more or fewer components than illustrated, or combine some components, or split some components, or have different component arrangements. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0117] This disclosure also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the ambiguity fixing method described in the above-described method embodiments. The storage medium can be a volatile or non-volatile computer-readable storage medium.

[0118] This disclosure also provides a computer program product, which stores a computer program. When the computer program is run by a processor, it executes the steps of the ambiguity fixing method provided in any of the above embodiments of this disclosure. For details, please refer to the above method embodiments, which will not be repeated here.

[0119] The aforementioned computer program product can be implemented through hardware, software, or a combination thereof. In one optional embodiment, the computer program product is specifically embodied in a computer storage medium, which can be a volatile or non-volatile computer-readable storage medium. In another optional embodiment, the computer program product is specifically embodied in a software product, such as a software development kit (SDK), etc.

[0120] Furthermore, embodiments of the subject matter and functional operation described in this specification can be implemented in the following ways: digital electronic circuits, tangibly embodied computer software or firmware, computer hardware including the structures disclosed in this specification and their structural equivalents, or combinations thereof. Embodiments of the subject matter described in this specification can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions encoded on a tangible, non-transitory program carrier for execution by a data processing apparatus or for controlling the operation of a data processing apparatus. Alternatively or additionally, program instructions may be encoded on artificially generated propagation signals, such as machine-generated electrical, optical, or electromagnetic signals, which are generated to encode information and transmit it to a suitable receiving device for execution by the data processing apparatus. The computer storage medium may be a machine-readable storage device, a machine-readable storage substrate, a random or serial access memory device, or combinations thereof.

[0121] The processing and logic flow described in this specification can be executed by one or more programmable computers that execute one or more computer programs to perform corresponding functions by operating on input data and generating output. The processing and logic flow can also be executed by dedicated logic circuitry—such as FPGAs (Field-Programmable Gate Arrays) or ASICs (Application-Specific Integrated Circuits), and the device can also be implemented as dedicated logic circuitry.

[0122] Suitable computers for executing computer programs include, for example, general-purpose and / or special-purpose microprocessors, or any other type of central processing unit. Typically, the central processing unit receives instructions and data from read-only memory and / or random access memory. The basic components of a computer include a central processing unit for implementing or executing instructions and one or more memory devices for storing instructions and data. Typically, a computer will also include one or more mass storage devices for storing data, such as disks, magneto-optical disks, or optical disks, or the computer will be operatively coupled to such mass storage devices to receive data from or transfer data to them, or both. However, a computer is not required to have such devices. Furthermore, a computer can be embedded in another device, such as a mobile phone, a personal digital assistant (PDA), a mobile audio or video player, a game console, a global positioning system (GPS) receiver, or a portable storage device such as a universal serial bus (USB) flash drive, to name a few.

[0123] Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media, and memory devices, such as semiconductor memory devices (e.g., EPROM, EEPROM, and flash memory devices), magnetic disks (e.g., internal hard disks or removable disks), magneto-optical disks, and CD-ROM and DVD-ROM disks. Processors and memory may be supplemented by or incorporated into dedicated logic circuitry.

[0124] While this specification contains numerous specific implementation details, these should not be construed as limiting the scope of any invention or the scope of the claims, but rather are primarily intended to describe features of specific embodiments of a particular invention. Certain features described in the various embodiments herein may also be implemented in combination in a single embodiment. Conversely, various features described in a single embodiment may also be implemented separately in various embodiments or in any suitable sub-combination. Furthermore, while features may function in certain combinations as described above and even initially claimed in this way, one or more features from a claimed combination may be removed from that combination in some cases, and a claimed combination may refer to a sub-combination or a variation thereof.

[0125] Similarly, although the operations are depicted in a specific order in the accompanying drawings, this should not be construed as requiring these operations to be performed in the specific order shown or sequentially, or requiring all illustrated operations to be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system modules and components in the above embodiments should not be construed as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

[0126] Thus, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve the desired result. Furthermore, the processes depicted in the drawings are not necessarily shown in a specific order or sequence to achieve the desired result. In some implementations, multitasking and parallel processing may be advantageous.

[0127] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method of ambiguity resolution, characterized by, The method is applied to a target carrier, the target carrier is in communication with a reference station, and the target carrier is provided with a multi-sensor odometer, and the method comprises the following steps: In the process of satellite positioning of the target carrier, for each double-difference satellite combination, according to an observation model of pseudo-range and carrier phase, a double-difference observation value of the target carrier and the reference station observing the double-difference satellite combination at the same time is determined; the double-difference satellite combination comprises a reference satellite and a non-reference satellite, the reference satellites of each double-difference satellite combination are the same and the non-reference satellites are different; Based on the double-difference observation value and a double-difference geometric distance between the target carrier, the reference station and the double-difference satellite combination, a double-difference pseudo-range residual and a double-difference phase residual corresponding to the double-difference satellite combination are determined; the double-difference geometric distance is determined based on a carrier predicted position obtained through the multi-sensor odometer; The double-difference phase residual is inter-epoch differenced to obtain a triple-difference phase residual corresponding to the double-difference satellite combination; Based on the triple-difference phase residual and the double-difference pseudo-range residual, an observation quality index of the target carrier to the double-difference satellite combination is determined; In order of the observation quality indices corresponding to each double-difference satellite combination from large to small, each double-difference satellite combination is sequentially eliminated until a removal cutoff condition is met, and based on the double-difference observation values corresponding to the double-difference satellite combinations remaining when the removal cutoff condition is met, ambiguities and the position of the target carrier are determined.

2. The method of claim 1, wherein, The double-difference observation value comprises a double-difference pseudo-range observation value and a double-difference phase observation value; the determination of the double-difference pseudo-range residual and the double-difference phase residual corresponding to the double-difference satellite combination based on the double-difference observation value and the double-difference geometric distance between the target carrier, the reference station and the double-difference satellite combination comprises: The double-difference pseudo-range residual corresponding to the double-difference satellite combination is determined based on the double-difference pseudo-range observation value and the double-difference geometric distance between the target carrier, the reference station and the double-difference satellite combination; The double-difference phase residual corresponding to the double-difference satellite combination is determined based on the double-difference phase observation value and the double-difference geometric distance.

3. The method of claim 1, wherein, The inter-epoch differencing of the double-difference phase residual to obtain the triple-difference phase residual corresponding to the double-difference satellite combination comprises: The triple-difference phase residual corresponding to the double-difference satellite combination is obtained by differencing the double-difference phase residual at a current epoch and the double-difference phase residual at a last adjacent epoch of the current epoch.

4. The method of claim 1, wherein, The inter-epoch differencing of the double-difference phase residual to obtain the triple-difference phase residual corresponding to the double-difference satellite combination comprises: The triple-difference phase residual corresponding to the double-difference satellite combination is obtained by differencing the double-difference phase residual at a current epoch and the double-difference phase residual at a target epoch; in the case that the double-difference phase residual jumps, the double-difference phase residual at the target epoch is the double-difference phase residual at the epoch where the jump occurs; in the case that the double-difference phase residual does not jump, the double-difference phase residual at the target epoch is determined based on the double-difference phase residual at a historical epoch.

5. The method of claim 1, wherein, The elimination cutoff condition comprises that the number of the remaining double-difference satellite combinations is less than a satellite combination number threshold, or that a position of the target carrier determined based on double-difference observations corresponding to the remaining double-difference satellite combinations is a correct fixed solution.

6. The method of claim 5, wherein, The eliminating each double-difference satellite combination in the order from large to small according to the observation quality index corresponding to each double-difference satellite combination, until the elimination cutoff condition is met, comprises: eliminating a preset number of double-difference satellite combinations in the order from large to small according to the observation quality index corresponding to each double-difference satellite combination, and comparing the number of the remaining double-difference satellite combinations with the satellite combination number threshold; in the case that the number of the remaining double-difference satellite combinations is less than the satellite combination number threshold, determining that the elimination cutoff condition is met; in the case that the number of the remaining double-difference satellite combinations is greater than or equal to the satellite combination number threshold, determining a candidate position solution of the target carrier and ambiguity based on double-difference observations corresponding to the remaining double-difference satellite combinations, taking the candidate position solution as a real-time kinematic fixed solution, performing pseudo-fixed detection on the real-time kinematic fixed solution based on the carrier predicted position, and obtaining a pseudo-fixed detection result; in the case that the pseudo-fixed detection result indicates that the real-time kinematic fixed solution is correctly fixed, determining that the elimination cutoff condition is met; in the case that the pseudo-fixed detection result indicates that the real-time kinematic fixed solution is pseudo-fixed, repeating the steps of eliminating a preset number of double-difference satellite combinations in the order from large to small according to the observation quality index corresponding to each double-difference satellite combination, and comparing the number of the remaining double-difference satellite combinations with the satellite combination number threshold, until the elimination cutoff condition is met.

7. The method of claim 6, wherein, The pseudo-fixed detection on the real-time kinematic fixed solution based on the carrier predicted position to obtain a pseudo-fixed detection result comprises: converting the carrier predicted position and the real-time kinematic fixed solution to the same coordinate system; determining first relative displacements of the carrier predicted position in multiple directions based on carrier coordinates of the carrier predicted position in the multiple directions after the coordinate system is converted, and determining second relative displacements of the real-time kinematic fixed solution in the multiple directions based on carrier coordinates of the real-time kinematic fixed solution in the multiple directions after the coordinate system is converted; determining a relative displacement residual based on the first relative displacements and the second relative displacements; determining a target statistic based on the relative displacement residual and a variance to which the relative displacement residual is subjected; determining a statistical threshold corresponding to the multiple directions according to degrees of freedom corresponding to the multiple directions, and determining that the real-time kinematic fixed solution is correctly fixed in the case that the target statistic is less than the statistical threshold, and vice versa.

8. An ambiguity resolution device, characterized by The device is applied to a target carrier, the target carrier communicates with a reference station, and the target carrier is provided with a multi-sensor odometer. The double-difference observation module is configured to determine, during satellite positioning of the target carrier, a double-difference observation value of the target carrier and the reference station when observing the double-difference satellite combination simultaneously according to an observation model of pseudo-range and carrier phase for each double-difference satellite combination; the double-difference satellite combination includes a reference satellite and a non-reference satellite, and each double-difference satellite combination includes the same reference satellite and different non-reference satellites; The residual determination module is configured to determine a double-difference pseudo-range residual and a double-difference phase residual corresponding to the double-difference satellite combination based on the double-difference observation value and a double-difference geometric distance between the target carrier, the reference station, and the double-difference satellite combination; the double-difference geometric distance is determined based on a carrier predicted position obtained by the multi-sensor odometer; The differential processing module is configured to perform inter-epoch differential processing on the double-difference phase residual to obtain a triple-difference phase residual corresponding to the double-difference satellite combination; The quality evaluation module is configured to determine an observation quality index of the target carrier to the double-difference satellite combination based on the triple-difference phase residual and the double-difference pseudo-range residual; The position determination module is configured to sequentially eliminate each double-difference satellite combination in a descending order of the observation quality index corresponding to each double-difference satellite combination until a removal cutoff condition is met, and determine an ambiguity and a position of the target carrier based on the double-difference observation value corresponding to the double-difference satellite combination remaining after the removal cutoff condition is met.

9. A computer device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the program to implement the steps of the ambiguity fixing method of any one of claims 1 to 7.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to implement the steps of the ambiguity fixing method of any one of claims 1 to 7.

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