Real-time estimation method for drift angle of beidou satellite based on inter-satellite link observation

Abstract

The application provides a Beidou satellite yaw attitude real-time estimation method based on inter-satellite link observation values, comprising the following steps: acquiring Ka-band inter-satellite link two-way observation values of Beidou No. 3 satellites; performing gross error elimination on the inter-satellite link observation values; performing epoch normalization on the inter-satellite link two-way observation values of all satellites near each epoch point, and adding each pair of link two-way observation values to form a clock error-free combined observation; establishing an observation equation after error correction, and estimating the Ka antenna phase center deviation of each satellite in each epoch; inversely solving the yaw attitude deviation of the satellite at each epoch according to the relationship between the yaw attitude change of the satellite and the single-epoch Ka antenna phase center deviation; and adding the yaw attitude deviation of the satellite to the nominal yaw attitude to obtain the estimated actual yaw attitude of the satellite. The application can improve the yaw attitude estimation precision of Beidou No. 3 satellites, realize high-precision monitoring on the actual change of the satellite attitude, and provide a reference for satellite attitude modeling during the earth shadow period.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of satellite navigation technology, and in particular to a Beidou satellite yaw attitude real-time estimation method based on inter-satellite link observation values. BACKGROUND

[0002] The satellite attitude describes the spatial orientation information of the satellite body. For an on-orbit navigation satellite, its attitude control needs to meet two conditions: first, the signal transmitting antenna needs to point to the center of the earth to ensure that the satellite signal can be effectively received by the ground user, and second, the satellite solar panel axis needs to be perpendicular to the direction of the sun to ensure that the satellite can obtain sufficient energy supply. Therefore, the attitude of the navigation satellite can be described by using an angle parameter, which is called the yaw attitude angle.

[0003] To ensure that the X and Z axes of the satellite body coordinate system are located in the sun-earth-satellite plane, the navigation satellite attitude control system needs to continuously adjust the yaw angle of the satellite. Therefore, the satellite can maintain a normal attitude, i.e., the nominal yaw attitude, at most of the time. However, when the sun, the earth, and the satellite are approximately in a straight line, i.e., the satellite is near the noon point and the midnight point, the satellite yaw rate will exceed the maximum adjustment rate of the attitude control system, resulting in noon maneuver and midnight maneuver. In addition, when some satellites enter the earth shadow, they cannot maintain the nominal attitude due to the failure of the solar sensitive period, resulting in an earth shadow maneuver.

[0004] Accurate acquisition of satellite attitude information is the basis for the realization of high-precision orbit determination and positioning of a satellite navigation system. In the case where satellite telemetry information is difficult to obtain, the actual yaw angle of the satellite can be estimated on-orbit using observation data. The estimated actual yaw angle can be used to monitor the attitude change of the satellite and to verify or establish a corresponding satellite attitude model. The estimation of the yaw attitude of a navigation satellite is performed by estimating the geometric invariants in the satellite body coordinate system to solve the yaw angle of the satellite. The vector composed of the satellite center of mass and the phase center of the satellite antenna or laser reflection prism can be selected, but due to the limitations of the laser measurement satellite observation plan, the navigation satellite cannot be continuously tracked for a full arc and the laser observation quantity is small. Therefore, the satellite antenna phase center estimation method is usually used. The existing methods are based on global tracking data to estimate the L-band antenna phase center in a single epoch. For the Beidou-3 (BDS-3) satellite, in addition to the L-band navigation antenna, a Ka-band inter-satellite link antenna is also provided, and the inter-satellite link observation can be continuously tracked for a full arc, which provides a new idea for the estimation of the yaw attitude of the BDS-3 satellite. SUMMARY

[0005] The present application provides a Beidou satellite yaw attitude real-time estimation method based on inter-satellite link observation values, which solves the defect that it is difficult to obtain and accurately estimate the yaw attitude information of the Beidou satellite in the prior art, and realizes accurate estimation of the yaw attitude of the Beidou satellite.

[0006] In a first aspect, the application provides a Beidou satellite yaw attitude real-time estimation method based on inter-satellite link observation values, comprising:

[0007] Obtaining inter-satellite link two-way observation values and auxiliary data of Ka band of Beidou No. 3 satellite;

[0008] Detecting and removing outliers of the inter-satellite link two-way observation values to obtain processed inter-satellite link two-way observation values;

[0009] Determining a preset ephemeris interval and a set ephemeris point, normalizing the inter-satellite link two-way observation values of all satellites with an interval of half of the preset ephemeris interval before and after the set ephemeris point to the set ephemeris point, and adding each pair of inter-satellite link two-way observation values to obtain clock error free combined observation values;

[0010] Error correcting the clock error free combined observation values, establishing an observation equation, linearizing the observation equation, and dynamically estimating the Ka antenna phase center offset of each satellite at each ephemeris point;

[0011] According to the mathematical relationship between the satellite yaw attitude change and the Ka antenna phase center offset of a single ephemeris, the satellite attitude deviation of the actual satellite yaw attitude relative to the nominal satellite yaw attitude at each ephemeris point is solved;

[0012] Adding the satellite attitude deviation to the nominal satellite yaw attitude at the corresponding time to obtain the estimated actual satellite yaw attitude.

[0013] According to the Beidou satellite yaw attitude real-time estimation method based on inter-satellite link observation values provided by the application, the inter-satellite link two-way observation values include Ka band two-way ranging observation values formed between satellites and between satellites and ground anchor stations;

[0014] The auxiliary data includes satellite broadcast ephemeris and inter-satellite link device time delay calibration values.

[0015] According to the Beidou satellite yaw attitude real-time estimation method based on inter-satellite link observation values provided by the application, the inter-satellite link two-way observation values are detected and removed for outliers to obtain processed inter-satellite link two-way observation values, comprising:

[0016] The inter-satellite link two-way observation values are detected and removed for outliers by using residual method or polynomial fitting method, wherein:

[0017] The residual method includes calculating the theoretical inter-satellite distance by using the predicted satellite orbit, clock error and pre-calibrated time delay parameters in the broadcast ephemeris, and obtaining the observation value residual by subtracting the inter-satellite link two-way observation values, if the residual exceeds the set threshold, the inter-satellite link two-way observation values are determined as outliers and removed;

[0018] The polynomial fitting method comprises: obtaining a fitting curve by polynomial fitting on the inter-satellite link two-way observation values of multiple epochs; determining that the inter-satellite link two-way observation value is a gross error if the difference between the fitting curve and the current epoch observation value exceeds a set threshold, and performing rejection.

[0019] According to the application, a Beidou satellite yaw attitude real-time estimation method based on inter-satellite link observation values is provided, a preset epoch interval and a set epoch point are determined, the inter-satellite link two-way observation values of all satellites with an interval of half of the preset epoch interval before and after the set epoch point are normalized to the set epoch point, and each pair of inter-satellite link two-way observation values is added to obtain a clock-free combined observation, comprising:

[0020] The inter-satellite link of Beidou No. 3 is measured in a time division multiple access system to obtain forward inter-satellite link ranging observation values and backward inter-satellite link ranging observation values, wherein the two-way measurement interval is the preset epoch interval;

[0021] The forward inter-satellite link ranging observation values and the backward inter-satellite link ranging observation values of each pair of inter-satellite links are corrected for satellite motion and clock error variation using the predicted satellite orbit and clock error, and are normalized to the set epoch point to obtain the forward inter-satellite link ranging observation values and the backward inter-satellite link ranging observation values at the same time;

[0022] The forward inter-satellite link ranging observation values and the backward inter-satellite link ranging observation values at the same time are added to obtain the clock-free combined observation.

[0023] According to the application, a Beidou satellite yaw attitude real-time estimation method based on inter-satellite link observation values is provided, the clock-free combined observation is error-corrected, an observation equation is established, and the observation equation is linearized to dynamically estimate the Ka antenna phase center deviation of each satellite at each epoch, comprising:

[0024] The satellite orbit and the hardware time delay are fixed as parameter estimates in precise orbit determination using the clock-free combined observation, and the satellite antenna phase center deviation is dynamically estimated as a random parameter to be estimated in a white noise mode;

[0025] An observation equation and a normal equation are established using all link observation values normalized to the same epoch time, and a sequential least square or Kalman filter method is used for network adjustment to solve the Ka antenna phase center deviation of each satellite.

[0026] According to the application, a Beidou satellite yaw attitude real-time estimation method based on inter-satellite link observation values is provided, the observation equation comprises:

[0027]

[0028] Wherein, A and B represent two Beidou No. 3 satellites, for Clock-bias-free combined observations of the inter-satellite link between satellites A and B at any given time. and for The positions of satellites A and B at any given time. and Let be the rotation matrix for satellites A and B from the star-fixed frame to the inertial frame or the Earth-fixed frame. and for Phase center deviation of Ka antennas of satellites A and B under fixed-plane conditions at any given time. The speed of light in a vacuum and For the inter-satellite link equipment latency between satellites A and B, Noise is measured for inter-satellite links.

[0029] According to the present invention, a real-time estimation method for the yaw attitude of BeiDou satellites based on inter-satellite link observations is provided, wherein the mathematical relationship includes:

[0030]

[0031] in, Let t be the deviation of the satellite's actual yaw angle from its nominal yaw angle at time t. and Let x and y be the initial values ​​of the phase center deviation of the Ka antenna. and The values ​​are the estimated phase center deviations of the Ka antenna in the x and y directions at time t. This is the arctangent function, which returns the arctangent in radians.

[0032] Secondly, the present invention also provides a real-time yaw attitude estimation system for BeiDou satellites based on inter-satellite link observations, comprising:

[0033] The acquisition module is used to acquire bidirectional observation values ​​and auxiliary data from the inter-satellite links of the Ka-band of BeiDou-3 satellites.

[0034] The preprocessing module is used to detect and remove gross errors in the inter-satellite link bidirectional observations to obtain the processed inter-satellite link bidirectional observations.

[0035] The normalization module is used to determine the preset epoch interval and the set epoch point, normalize the inter-satellite link bidirectional observations of all satellites that are half the preset epoch interval before and after the set epoch point to the set epoch point, and add the bidirectional observations of each pair of inter-satellite links to obtain the clock-bias-free combined observations.

[0036] an estimation module, configured to correct errors of the clock-free combined observations, establish an observation equation, linearize the observation equation, and dynamically estimate Ka antenna phase center offsets of each satellite per epoch;

[0037] a solving module, configured to solve satellite attitude offsets of actual yaw attitudes of the satellites relative to nominal yaw attitudes of the satellites per epoch according to a mathematical relationship between changes in the yaw attitudes of the satellites and the Ka antenna phase center offsets per epoch;

[0038] a calculating module, configured to add the satellite attitude offsets to the nominal yaw attitudes of the satellites at corresponding time points to obtain estimated actual yaw attitudes of the satellites.

[0039] In a third aspect, the present application also provides an electronic device, which comprises a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and the processor implements the real-time estimation method of the yaw attitude of the Beidou satellite based on the inter-satellite link observation values when executing the program.

[0040] In a fourth aspect, the present application also provides a non-transitory computer readable storage medium, which stores a computer program, and the computer program implements the real-time estimation method of the yaw attitude of the Beidou satellite based on the inter-satellite link observation values when executed by a processor.

[0041] The real-time estimation method of the yaw attitude of the Beidou satellite based on the inter-satellite link observation values provided by the present application realizes high-precision estimation of the yaw attitude of the satellite by utilizing the good spatial geometric structure of the Ka observation values between the Beidou No. 3 high-orbit and medium-orbit satellites, the medium-orbit and medium-orbit satellites, and the high-orbit and ground station satellites, and solving the yaw attitude of the Beidou satellite; compared with the estimation of the yaw attitude of the satellite by using L-band satellite-ground data, the yaw attitude estimation method based on the inter-satellite link observation values provided by the present application does not contain satellite and receiver clock errors and ambiguity parameters in the data processing process, is more convenient to operate, and is more reliable in results; application of the yaw attitude estimation method provided by the present application can realize real-time monitoring of the actual yaw attitude of the Beidou satellite, and provides a basis for high-precision attitude modeling and precise orbiting positioning of the Beidou satellite. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0043] Figure 1 is a flowchart of the real-time estimation method of the yaw attitude of the Beidou satellite based on the inter-satellite link observation values provided by the present application;

[0044] Figure 2 is a flow chart of the inter-satellite link observation value gross error detection provided by the present application;

[0045] Figure 3 is a flow chart of the inter-satellite link two-way ranging observation value epoch normalization provided by the present application

[0046] Figure 4 is a flow chart of the single-epoch estimation of the Ka antenna phase center offset of a satellite provided by the present application;

[0047] Figure 5 is a structural schematic diagram of the Beidou satellite yaw attitude real-time estimation system based on inter-satellite link observation values provided by the present application;

[0048] Figure 6 is a structural schematic diagram of an electronic device provided by the present application. DETAILED DESCRIPTION

[0049] In order to make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0050] Figure 1 is a flow schematic diagram of the Beidou satellite yaw attitude real-time estimation method based on inter-satellite link observation values provided by the present application, as shown in Figure 1 , comprising:

[0051] Step 100: obtaining the inter-satellite link two-way observation values of the Ka band of the Beidou-3 satellite and auxiliary data;

[0052] Step 200: performing gross error detection and elimination on the inter-satellite link two-way observation values to obtain processed inter-satellite link two-way observation values;

[0053] Step 300: determining a preset epoch interval and a set epoch point, normalizing the inter-satellite link two-way observation values of all satellites with an interval of half of the preset epoch interval before and after the set epoch point to the set epoch point, and adding each pair of inter-satellite link two-way observation values to obtain clock-error-free combined observation values;

[0054] Step 400: performing error correction on the clock-error-free combined observation values, establishing an observation equation, linearizing the observation equation, and dynamically estimating the Ka antenna phase center offset of each satellite epoch by epoch;

[0055] Step 500: according to the mathematical relationship between the satellite yaw attitude change and the single-epoch Ka antenna phase center deviation, the satellite attitude deviation of the actual satellite yaw attitude at each epoch relative to the nominal satellite yaw attitude is solved;

[0056] Step 600: the satellite attitude deviation and the nominal satellite yaw attitude at the corresponding moment are added to obtain the estimated actual satellite yaw attitude.

[0057] The embodiment of the application obtains the Ka band inter-satellite link two-way observation value of the Beidou-3 satellite, removes the gross error of the inter-satellite link observation value, normalizes the inter-satellite link two-way observation value of all satellites near each epoch point, adds each pair of link two-way observation values to form a clock-free combined observation, establishes an observation equation after error correction, estimates the Ka antenna phase center deviation of each satellite epoch by epoch, inversely solves the yaw attitude deviation of the satellite at each epoch according to the relationship between the satellite yaw attitude change and the single-epoch Ka antenna phase center deviation, and adds the satellite attitude deviation and the nominal yaw attitude to obtain the estimated actual satellite yaw attitude.

[0058] The application can improve the estimation accuracy of the Beidou-3 satellite yaw attitude, realize high-precision monitoring of the actual change of the satellite attitude, and provide a reference for satellite attitude modeling during the earth shadow period.

[0059] Based on the above embodiment, the inter-satellite link observation value of the Beidou-3 satellite in step 100 includes Ka band two-way ranging observation values formed between satellites and between satellites and ground anchor stations, and the auxiliary data includes satellite broadcast ephemeris and inter-satellite link device time delay calibration values and the like.

[0060] Based on the above embodiment, as shown in the step 200, the step 200 includes: Figure 2

[0061] The embodiment of the application can use the residual method and the polynomial fitting method to detect the gross error of the Beidou inter-satellite link observation value.

[0062] The residual method is to calculate the theoretical inter-satellite distance by using the predicted satellite orbit, clock error in the broadcast ephemeris and the pre-calibrated time delay parameter, and to obtain the observation value residual by subtracting the inter-satellite link observation value, and when the residual exceeds the set threshold, the observation value is considered to be a gross error; the polynomial fitting method is to obtain a fitting curve by polynomial fitting of the inter-satellite observation value of multiple epochs, and if the difference between the fitting curve and the current epoch observation value exceeds the set threshold, the inter-satellite link two-way observation value is determined to be a gross error.

[0063] If the gross error does not exceed the set threshold, the data is considered to be normal, otherwise the data is removed.

[0064] Based on the above embodiment, the step 300 includes:

[0065] ​The inter-satellite link of the Beidou-3 adopts a time division multiple access system to perform bidirectional measurement, and specifically, the time instants of the inter-satellite bidirectional measurement are different, but the interval is not more than 3 seconds.

[0066] In order to combine the bidirectional observation values to eliminate certain errors, it is necessary to normalize the bidirectional observation values at different measurement instants to the same instant; the predicted satellite orbit and clock difference are used to correct the satellite motion and clock difference variation of the forward and backward ranging observation values of each pair of links, so as to be reduced to the same instant, for example, a certain ephemeris interval t (such as 60 seconds) is set, and the inter-satellite link bidirectional observation values of all satellites within t / 2 before and after the ephemeris interval are normalized to the set ephemeris point.

[0067] Then, the forward and backward observation values are added and combined to eliminate the satellite clock difference information, and the clock-difference-free combined observation of the inter-satellite link is obtained; the ephemeris normalization process of the inter-satellite link bidirectional ranging observation value is as shown in Figure 3

[0068] The clock-difference-free combined observation of the inter-satellite link is obtained by normalizing the bidirectional observation values of each pair of links to the same instant using the broadcast ephemeris, and then adding and combining the bidirectional observation values to eliminate the satellite clock difference information.

[0069] Based on the above embodiment, step 400 comprises:

[0070] The embodiment of the application first uses the clock-difference-free combined observation of the Beidou-3 inter-satellite link for precise orbit determination, then fixes the satellite orbit and hardware time delay as the parameter estimation in the precise orbit determination, and uses white noise mode to dynamically estimate the satellite antenna phase center offset as a random parameter to be estimated; in the data processing of parameter estimation, a data processing ephemeris interval of 60 seconds is set, the Beidou-3 inter-satellite link observation data within the next 30 seconds are normalized to the interval point, then an observation model and normal equation are established, the least square method is used for network adjustment, and the Ka antenna phase center offset of each satellite is solved in a single ephemeris; the single ephemeris estimation process of the satellite Ka antenna phase center offset is as shown in Figure 4

[0071] The observation equation is:

[0072]

[0073] Wherein, A and B represent two Beidou-3 satellites, are the clock-difference-free combined observation of the inter-satellite link between satellites A and B at the instant, and are the positions of satellites A and B at the instant, and are the rotation matrices of satellites A and B from the star-fixed system to the inertial system or the earth-fixed system,​​ and is the Ka antenna phase center bias of satellite A and B in the star-fixed system at time t, is the speed of light in vacuum, and is the inter-satellite link device delay of satellite A and B, is the inter-satellite link measurement noise; the satellite position and the inter-satellite link device delay are fixed as the estimated values in advance, the rotation matrix of the star-fixed system to the inertial system or the earth-fixed system is calculated by using the nominal yaw attitude, and the to-be-estimated parameter is the single-epoch Ka antenna phase center bias of the satellite.

[0074] Further, the estimation method of the single-epoch satellite Ka antenna phase center bias is as follows: an observation model and a normal equation are established by using all the link observation values at the same epoch time, a sequential least square or Kalman filtering method is used for global adjustment, and the single-epoch Ka antenna phase center bias of each satellite is solved.

[0075] Based on the above embodiment, the mathematical relationship in step 500 includes:

[0076]

[0077] wherein, is the deviation of the actual yaw angle of the satellite at time t from the nominal yaw angle, and is the initial value of the Ka antenna phase center bias in the x and y directions, and is the estimated value of the Ka antenna phase center bias in the x and y directions at time t, is the arctangent function, which returns the arctangent in radians.

[0078] Finally, the satellite attitude bias is added to the nominal yaw attitude of the satellite at the corresponding time, so as to obtain the estimated actual yaw attitude of the satellite.

[0079] The following describes the Beidou satellite yaw attitude real-time estimation system based on inter-satellite link observation values provided by the present application, which can be correspondingly referred to the Beidou satellite yaw attitude real-time estimation method based on inter-satellite link observation values described above.

[0080] Figure 5 is a structural schematic diagram of the Beidou satellite yaw attitude real-time estimation system based on inter-satellite link observation values provided by the embodiment of the present application, as shown in Figure 5 , which comprises an acquisition module 51, a preprocessing module 52, a normalization module 53, an estimation module 54, a solving module 55 and a calculation module 56, wherein:

[0081] The acquisition module 51 is configured to acquire the inter-satellite link bi-directional observation values and auxiliary data of the Beidou-3 satellite Ka band; the preprocessing module 52 is configured to detect and eliminate the coarse errors of the inter-satellite link bi-directional observation values, to obtain the processed inter-satellite link bi-directional observation values; the normalization module 53 is configured to determine a preset epoch interval and a set epoch point, to normalize the inter-satellite link bi-directional observation values of all satellites with an interval of half of the preset epoch interval before and after the set epoch point to the set epoch point, and to add each pair of inter-satellite link bi-directional observation values to obtain a clock error free combined observation; the estimation module 54 is configured to correct the errors of the clock error free combined observation, to establish an observation equation, to linearize the observation equation, and to dynamically estimate the Ka antenna phase center offset of each satellite at each epoch; the solving module 55 is configured to solve the satellite attitude deviation of the actual yaw attitude of the satellite at each epoch relative to the nominal yaw attitude of the satellite according to the mathematical relationship between the satellite yaw attitude change and the Ka antenna phase center offset of a single epoch; and the calculation module 56 is configured to add the satellite attitude deviation to the nominal yaw attitude of the satellite at the corresponding time to obtain the estimated actual yaw attitude of the satellite.

[0082] Figure 6 An example of a schematic diagram of a physical structure of an electronic device is shown in Figure 6 The electronic device can include a processor 610, a communications interface 620, a memory 630, and a communications bus 640, wherein the processor 610, the communications interface 620, and the memory 630 communicate with each other through the communications bus 640. The processor 610 can invoke a logical instruction in the memory 630 to execute a Beidou satellite yaw attitude real-time estimation method based on inter-satellite link observation values, which includes detecting and eliminating coarse errors of inter-satellite link bi-directional observation values to obtain processed inter-satellite link bi-directional observation values;

[0083] The normalization module 53 is configured to determine a preset epoch interval and a set epoch point, to normalize the inter-satellite link bi-directional observation values of all satellites with an interval of half of the preset epoch interval before and after the set epoch point to the set epoch point, and to add each pair of inter-satellite link bi-directional observation values to obtain a clock error free combined observation; the estimation module 54 is configured to correct the errors of the clock error free combined observation, to establish an observation equation, to linearize the observation equation, and to dynamically estimate the Ka antenna phase center offset of each satellite at each epoch; the solving module 55 is configured to solve the satellite attitude deviation of the actual yaw attitude of the satellite at each epoch relative to the nominal yaw attitude of the satellite according to the mathematical relationship between the satellite yaw attitude change and the Ka antenna phase center offset of a single epoch; and the calculation module 56 is configured to add the satellite attitude deviation to the nominal yaw attitude of the satellite at the corresponding time to obtain the estimated actual yaw attitude of the satellite.

[0084] In addition, the logic instructions in the memory 630 described above can be implemented in the form of a software function unit and sold or used as an independent product, which can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the parts that contribute to the prior art or parts of the technical solutions can be embodied in the form of a software product, which is stored in a storage medium, includes several instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in various embodiments of the present application. And the aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disk and various program code storage media.

[0085] In another aspect, the present application also provides a non-transitory computer readable storage medium having stored thereon a computer program, which, when executed by a processor, implements a Beidou satellite yaw attitude real-time estimation method based on inter-satellite link observation values provided by the above method, the method comprising: performing rough error detection and elimination on inter-satellite link two-way observation values to obtain processed inter-satellite link two-way observation values;

[0086] determining a preset epoch interval and a set epoch point, normalizing the inter-satellite link two-way observation values of all satellites with an interval of half of the preset epoch interval before and after the set epoch point to the set epoch point, and adding each pair of inter-satellite link two-way observation values to obtain a clock error free combined observation; performing error correction on the clock error free combined observation to establish an observation equation, linearizing the observation equation, and dynamically estimating the Ka antenna phase center offset of each satellite at each epoch; according to the mathematical relationship between the satellite yaw attitude change and the Ka antenna phase center offset of a single epoch, solving the satellite attitude deviation of the actual satellite yaw attitude relative to the nominal satellite yaw attitude at each epoch; and adding the satellite attitude deviation and the nominal satellite yaw attitude at the corresponding time to obtain the estimated actual satellite yaw attitude.

[0087] The device embodiments described above are only schematic, wherein the units illustrated as separate components can or can not be physically separated, and the components illustrated as units can or can not be physical units, i.e., they can be located in one place, or distributed on multiple network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the present embodiment. Those skilled in the art can understand and implement without creative labor.

[0088] Those skilled in the art can clearly understand the technical solutions of the various embodiments from the above description of the embodiments, and the various embodiments can be implemented by means of software with the necessary general hardware platforms, and of course, can also be implemented by hardware. Based on such understanding, the above technical solutions, essentially or in other words, the part of the prior art that makes a contribution, can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, and the like, and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0089] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for some technical features therein; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for real-time estimation of the yaw attitude of a Beidou satellite based on inter-satellite link observations, characterized in that, The method comprises the following steps: Obtaining the inter-satellite link bi-directional observation values of the Beidou-3 satellite Ka band and auxiliary data; Performing rough error detection and elimination on the inter-satellite link bi-directional observation values to obtain processed inter-satellite link bi-directional observation values; Determining a preset epoch interval and a set epoch point, normalizing the inter-satellite link bi-directional observation values of all satellites with an interval of half of the preset epoch interval before and after the set epoch point to the set epoch point, and adding each pair of inter-satellite link bi-directional observation values to obtain clock error free combined observation values; Performing error correction on the clock error free combined observation values, establishing an observation equation, linearizing the observation equation, and dynamically estimating the Ka antenna phase center offset of each satellite at each epoch; According to the mathematical relationship between the satellite yaw attitude change and the Ka antenna phase center offset of a single epoch, the satellite attitude offset of each epoch is solved, which is the actual yaw attitude of the satellite relative to the nominal yaw attitude of the satellite; Adding the satellite attitude offset to the nominal yaw attitude of the satellite at the corresponding time to obtain the estimated actual yaw attitude of the satellite; Performing error correction on the clock error free combined observation values, establishing an observation equation, linearizing the observation equation, and dynamically estimating the Ka antenna phase center offset of each satellite at each epoch, comprising: Using the clock error free combined observation values for precise orbit determination, fixing the satellite orbit and hardware time delay as parameter estimates in the precise orbit determination, and dynamically estimating the satellite antenna phase center offset as a random parameter using white noise mode; Using all link observation values normalized to the same epoch to establish an observation equation and a normal equation, and using sequential least squares or Kalman filtering method for network adjustment to solve the Ka antenna phase center offset of each satellite; The observation equation comprises: where A and B represent two BeiDou-3 satellites, For the clockless combination observation of the inter-satellite link between satellites A and B at time t, and For the positions of satellites A and B at time t, and For the rotation matrix of satellites A and B from the star-fixed system to the inertial system or the earth-fixed system, and For the phase center offset of the Ka antenna of satellites A and B in the star-fixed system at time t, is the speed of light in a vacuum, and is the inter-satellite link equipment delay of satellites A and B, is the inter-satellite link measurement noise; The mathematical relationship comprises: wherein, is the deviation of the actual yaw angle of the satellite at time t from the nominal yaw angle of the satellite, and is the initial value of the deviation of the phase center of the Ka antenna in the x and y directions, and is the estimated value of the deviation of the phase center of the Ka antenna in the x and y directions at time t, is the arctangent function that returns the arctangent in radians.

2. The method of Claim 1, wherein the method comprises: The inter-satellite link bi-directional observation values comprise Ka band bi-directional ranging observation values formed between satellites and between satellites and ground anchor stations; The auxiliary data comprise satellite broadcast ephemeris and inter-satellite link device time delay calibration values.

3. The method of Claim 1, wherein the method comprises: Performing rough error detection and elimination on the inter-satellite link bi-directional observation values to obtain processed inter-satellite link bi-directional observation values, comprising: Using residual method or polynomial fitting method to perform rough error detection and elimination on the inter-satellite link bi-directional observation values, wherein: The residual method comprises calculating the theoretical inter-satellite distance using the predicted satellite orbit, clock error and pre-calibrated time delay parameter in the broadcast ephemeris, and obtaining the observation value residual by subtracting the inter-satellite link bi-directional observation values, if the residual exceeds the set threshold, the inter-satellite link bi-directional observation value is determined as a rough error and is eliminated; The polynomial fitting method comprises obtaining a fitting curve by polynomial fitting on the inter-satellite link bi-directional observation values of multiple epochs, if the difference between the fitting curve and the current epoch observation value exceeds the set threshold, the inter-satellite link bi-directional observation value is determined as a rough error and is eliminated.

4. The method of Claim 1, wherein the method is characterized by, Determining a preset epoch interval and a set epoch point, normalizing the inter-satellite link bi-directional observation values of all satellites with an interval of half of the preset epoch interval before and after the set epoch point to the set epoch point, and adding each pair of inter-satellite link bi-directional observation values to obtain clock error free combined observation values, comprising: The time division multiple access system is adopted to perform bidirectional measurement on the Beidou No. 3 inter-satellite link, and forward inter-satellite link ranging observation values and backward inter-satellite link ranging observation values are obtained, wherein the bidirectional measurement interval is the preset epoch interval; The forward inter-satellite link ranging observation values and the backward inter-satellite link ranging observation values of each pair of inter-satellite links are corrected for satellite motion and clock difference variation by using the predicted satellite orbit and clock difference, and are normalized to the set epoch point, so that the forward inter-satellite link ranging observation values and the backward inter-satellite link ranging observation values at the same time are obtained; The forward inter-satellite link ranging observation values and the backward inter-satellite link ranging observation values at the same time are added to obtain the clock-difference-free combined observation.

5. A BeiDou satellite yaw attitude real-time estimation system based on inter-satellite link observations, based on the BeiDou satellite yaw attitude real-time estimation method based on inter-satellite link observations of any one of claims 1 to 4, characterized in that, It comprises: An acquisition module is configured to acquire bidirectional observation values of inter-satellite links of Beidou No. 3 satellites in Ka band and auxiliary data; A preprocessing module is configured to perform rough error detection and elimination on the bidirectional observation values of inter-satellite links to obtain processed bidirectional observation values of inter-satellite links; A normalization module is configured to determine a preset epoch interval and a set epoch point, normalize the bidirectional observation values of inter-satellite links of all satellites within an interval of half of the preset epoch interval before and after the set epoch point to the set epoch point, and add the bidirectional observation values of each pair of inter-satellite links to obtain clock-difference-free combined observation; An estimation module is configured to perform error correction on the clock-difference-free combined observation, establish an observation equation, linearize the observation equation, and dynamically estimate Ka antenna phase center offsets of each satellite at each epoch; A solving module is configured to solve satellite attitude offsets of actual yaw attitudes of satellites relative to nominal yaw attitudes of satellites at each epoch according to a mathematical relationship between satellite yaw attitude changes and Ka antenna phase center offsets of a single epoch; A calculation module is configured to add the satellite attitude offsets to the nominal yaw attitudes of satellites at corresponding time to obtain estimated actual yaw attitudes of satellites.

6. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor implements the Beidou satellite yaw attitude real-time estimation method based on inter-satellite link observation values according to any one of claims 1 to 4 when executing the program.

7. A non-transitory computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program implements the Beidou satellite yaw attitude real-time estimation method based on inter-satellite link observation values according to any one of claims 1 to 4 when executed by the processor.

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