A satellite attitude determination accuracy evaluation method and system

Abstract

The invention relates to a satellite attitude determination accuracy evaluation method and system, comprising: using a satellite onboard computer to collect quaternion original measurement data of all star sensors installed on two or more satellites, transmitting all the original measurement data of the star sensors and the satellite attitude quaternion determined in real time by the onboard computer to the ground through a data transmission channel; obtaining the inertial attitude angular velocity of the satellite three axes and the inertial attitude angular velocity of the three axes of each star sensor during the evaluation period; processing the acquired star sensor original measurement data and the attitude quaternion determined in real time on the satellite, and further obtaining the high-frequency part and low-frequency trend item of the two data measurement errors; processing the high-frequency part of the measurement error to obtain the satellite attitude determination high-frequency error evaluation standard and evaluation result; processing the measurement error low-frequency trend item to obtain the star sensor installation benchmark stability evaluation result, the satellite attitude determination low-frequency error evaluation standard and evaluation result.

Description

Technical Field

[0001] The present invention relates to a satellite attitude determination accuracy assessment method and system, which belongs to the technical field of satellite on-orbit performance assessment and can be applied to the rapid assessment of attitude determination accuracy after a satellite enters orbit. Background Art

[0002] As the requirements for satellite payload attitude determination accuracy in space missions continue to increase, the attitude measurement accuracy of satellite sensors is also increasing. At present, the sensors with the highest attitude measurement accuracy on almost all satellites are star sensors, but there is still a lack of a universal, effective and fast evaluation method for satellite attitude determination accuracy based on star sensor measurements.

[0003] Most low-orbit remote sensing satellites use satellite-ground joint calibration to indirectly evaluate the accuracy of satellite attitude determination. The satellite images the ground calibration field, matches the control points of known geographic information in the remote sensing image with the satellite image, calibrates the systematic error of satellite positioning, and indirectly evaluates the level of satellite attitude determination accuracy. The shortcomings of this method are:

[0004] The positioning error includes multiple errors, such as attitude determination error, orbit determination error, camera internal azimuth error, and time error. It is impossible to separate the attitude determination error alone.

[0005] Accuracy assessment can only be performed on areas with ground control points. It is impossible to assess other areas without calibration sites / control points. In deserts, oceans, dense forests, borders, and overseas areas, it is often difficult or even impossible to obtain ground control points because the ground features are not obvious or personnel cannot reach them.

[0006] The satellite-ground joint calibration requires the cooperation of the ground calibration site, involves multiple units, is difficult to operate, consumes a lot of resources, and has a long cycle.

[0007] In 2014, Zhou Xiaohua proposed an accuracy analysis method for determining the attitude of a satellite system using dual star sensors based on the dual-vector TRIAD method. Under the premise of known star sensor attitude determination accuracy, the functional relationship between the maximum error of satellite attitude and the star sensor layout angle was derived. The shortcomings of this method are:

[0008] The number of star sensors is limited to 2;

[0009] The installation angles of the two star sensors are limited, and they can only be installed symmetrically relative to the YOZ plane of the satellite system;

[0010] The effect of the base deformation of the star sensor installation on the attitude determination accuracy is ignored, and the base deformation is a very important item in the satellite attitude determination error. Summary of the invention

[0011] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to provide a satellite attitude determination accuracy assessment method and system, to achieve rapid assessment of satellite inertial system attitude determination accuracy based on star sensor or star camera measurement and star sensor installation benchmark stability assessment, to reduce the assessment cost of attitude determination accuracy indicators in the early stage of satellite orbit entry, and to accelerate the rapid performance assessment of satellite systems after orbit entry.

[0012] The technical solution of the present invention is:

[0013] A satellite attitude determination accuracy assessment method, the steps are as follows:

[0014] Step S1, using a satellite onboard computer to collect quaternion raw measurement data of all star sensors installed on the satellite, two or more, and transmit all the star sensor raw measurement data and the satellite attitude quaternion determined in real time by the onboard computer to the ground through a data transmission channel;

[0015] Step S2, obtaining the inertial attitude angular velocity of the three axes of the satellite and the inertial attitude angular velocity of the three axes of each star sensor during the evaluation period;

[0016] Step S3, processing the original star-sensing measurement data obtained in step S1 and the attitude quaternion determined in real time on the satellite, and combining the information obtained in step S2 to obtain the high-frequency part and low-frequency trend item in the measurement errors of the two data;

[0017] Step S4, processing the high-frequency part of the measurement error in step S3 to obtain a satellite attitude determination high-frequency error evaluation standard and evaluation result;

[0018] Step S5, processing the low-frequency trend item of the measurement error in step S3, and obtaining the stability evaluation result of the star-sensing installation benchmark, the evaluation standard and evaluation result of the low-frequency error of satellite attitude determination.

[0019] Furthermore, in step S1, the star sensor may also be a star camera or a combination of a star sensor and a star camera.

[0020] Furthermore, in step S2, the satellite inertial attitude angular velocity is obtained by on-board telemetry or calculated according to the characteristics of the satellite orbit. Further, the inertial angular velocity of the three axes of the star sensor is obtained in combination with the installation matrix of the star sensor under the satellite system; the star sensor installation matrix is ​​obtained by ground mechanical calibration or by on-orbit calibration of the star sensor.

[0021] Furthermore, in step S3, the on-board star sensor measurement data and attitude determination results are processed by a fitting method or an angle method, and then filtered by a low-pass filter or a sliding window filter method to separate the high-frequency part and the low-frequency trend item.

[0022] Furthermore, the angle method is used to analyze the on-board star sensor measurement data and attitude determination results, and separate the high-frequency part and the low-frequency trend item, specifically:

[0023] The attitude quaternion at each moment is converted into the attitude conversion matrix from the J2000 inertial system to the current system. Each row of the matrix is ​​the vector representation of the X, Y, and Z axes of the current system in the J2000 system. The attitude matrix represented by the quaternion Q at time k is:

[0024]

[0025] in,

[0026]

[0027] In the above formula, the column vector is the vector part, q 0 is the scalar part, C(Q k ) is the posture matrix at time k, e x 、e y 、e z are the three-axis unit vectors of the reference rotation axis, φ is the rotation angle;

[0028] The origin of the J2000 coordinate system is located at the Earth's center of mass, the Z axis points to the J2000.0 mean celestial pole, and the X axis points to the J2000.0 mean vernal equinox;

[0029] Calculate the angle curve of the three axes of this system at the same moment:

[0030] ZGar k =arccos(Z k-1 ·Z k )

[0031] AngX k =arccos(X k-1 ·X k )

[0032] AngY k =arccos(Y k-1 ·Y k )

[0033] The angle curve contains three parts: the projection of the system's inertial angular velocity on the three axes, the low-frequency trend of the system's three-axis pointing error, and the high-frequency part of the system's three-axis pointing error. Next, these three items are separated one by one:

[0034] The angle curve is filtered by low-pass filtering or sliding window filtering. The result is subtracted from the filtered curve by the original curve and then divided by Get the high-frequency part of the pointing error:

[0035]

[0036]

[0037]

[0038] in, Represents the three-axis angle curve after filtering;

[0039] According to the satellite orbit and attitude operation rules, the three-axis theoretical inertial angular velocity of the system is calculated, and the theoretical inertial angular velocity is subtracted from the filtered curve to obtain the low-frequency trend term of the three-axis pointing error:

[0040]

[0041]

[0042]

[0043] Among them, VX, VY, VZ are the theoretical inertial angular velocities of the three axes of this system, T s For data sampling period, use LF X , LF Y , LF Z Represents the low-frequency trend term of the satellite's X, Y, and Z axes.

[0044] Furthermore, the step S4 processes the high-frequency part of the measurement error to obtain the satellite attitude determination high-frequency error evaluation standard and evaluation result, which are specifically:

[0045] According to the calculation, the high-frequency measurement error HF of the optical axis of each star sensor is obtained STSA HF STSB HF STSC And the satellite Z-axis attitude determination high frequency error HF Z , the evaluation criteria for high-frequency error in satellite Z-axis attitude determination are:

[0046]

[0047] Where N is the number of star sensors involved in attitude determination;

[0048] Evaluate the high-frequency accuracy of satellite attitude determination:

[0049] when When the satellite Z-axis attitude is determined, the high-frequency accuracy is within the normal range. Z The smaller the value, the higher the high frequency accuracy;

[0050] when When the satellite Z-axis attitude is determined, the high-frequency accuracy is poor.Z The larger the value, the worse the high frequency accuracy.

[0051] Furthermore, the step S5 processes the low-frequency trend item of the measurement error to obtain the stability evaluation result of the star-sensing installation benchmark, the evaluation standard and evaluation result of the low-frequency error determined by the satellite attitude, which are specifically:

[0052] When using Samsung Sensing, there are

[0053]

[0054] in,

[0055] ——Evaluation criteria for low-frequency error of satellite +Z-axis attitude determination. During the calculation process, only the original quaternions of each star sensor on orbit are used, which represents the low-frequency accuracy of attitude determination that the satellite should achieve under the conditions of the configured star sensor measurement accuracy and installation benchmark deformation;

[0056] ω i ——The configurable weighted value is selected based on the actual attitude determination algorithm, the on-orbit illumination conditions of each star sensor, the thermal control environment, the installation orientation, etc., and represents the contribution of each star sensor's low-frequency error term to the satellite's total low-frequency error;

[0057] The low-frequency determination accuracy that can actually be achieved by the satellite is obtained by the following method:

[0058] Depend on

[0059] LF AngZA =LF STSA +LF Z +LF Flat

[0060] LF AngZB =LF STSB +LF Z +LF Flat

[0061] LF AngZC =LF STSC +LF Z +LF Flat

[0062] Among them, LF STSA , LF STSB , LF STSC is the low-frequency term in the measurement error of each star-sensing optical axis, LF Flat Deformation of the benchmark for star-sensing installation;

[0063] Combination From the expression of , we can see that

[0064]

[0065] Evaluate the low-frequency accuracy of satellite attitude determination:

[0066] when When the satellite Z-axis attitude is determined, the low-frequency accuracy is within the normal range. Z The smaller the value, the higher the low frequency accuracy;

[0067] when When the satellite Z-axis attitude is determined, the low-frequency accuracy is poor. Z The larger the value, the worse the low-frequency accuracy.

[0068] Furthermore, the sum of the weighted values Take 0.8~3, where N is the number of star sensors involved in attitude determination.

[0069] Furthermore, the present invention also proposes a satellite attitude determination accuracy assessment system, comprising:

[0070] Raw measurement data acquisition module: using the satellite onboard computer, collects the quaternion raw measurement data of all star sensors installed on the satellite, two or more, and transmits all the raw measurement data of the star sensors and the satellite attitude quaternion determined in real time by the onboard computer to the ground through the data transmission channel;

[0071] Three-axis attitude angular velocity acquisition module: acquires the inertial attitude angular velocity of the satellite's three axes and the inertial attitude angular velocity of each star sensor's three axes during the evaluation period;

[0072] High-frequency and low-frequency separation module: Processes the original star-sensing measurement data obtained in the original measurement data acquisition module and the attitude quaternion determined in real time on the satellite, and combines the information obtained in the three-axis attitude angular velocity acquisition module to obtain the high-frequency part and low-frequency trend item in the measurement errors of the two data;

[0073] High-frequency processing evaluation module: processes the high-frequency part of the measurement error in the high-frequency and low-frequency separation module to obtain the evaluation standard and evaluation results of the high-frequency error of satellite attitude determination;

[0074] Low-frequency processing and evaluation module: processes the low-frequency trend items of the measurement errors in the high-frequency and low-frequency separation module to obtain the star-sensing installation benchmark stability evaluation results, satellite attitude determination low-frequency error evaluation standards and evaluation results.

[0075] The beneficial effects of the present invention compared with the prior art are:

[0076] (1) Filling the technical gap in related fields: At present, there is a lack of effective and fast satellite attitude determination accuracy evaluation methods in China. The attitude determination accuracy evaluation method proposed in this invention fills the gap in related technical fields in China.

[0077] (2) Wide range of applications - the satellite attitude determination error model and method constructed by the present invention are applicable to most satellites and spacecraft, including: satellites that use no less than two star sensors as the highest precision attitude measurement sensors, and satellites whose orbits are not return orbits or halo orbits. A halo orbit refers to an orbit in which a spacecraft moves around a libration point (Lagrange point) in a restricted three-body problem in a closed curve. A halo orbit that moves around the libration point of the Sun-Earth system is called a solar halo orbit, and a halo orbit that moves around the libration point of the Earth-Moon system is called a lunar halo orbit.

[0078] (3) Short evaluation cycle: The data input used in the present invention is all original data on the satellite, which can be transmitted to the ground through the digital transmission channel for accuracy evaluation, and the time cycle is short.

[0079] (4) Small resource occupation - The method used in the present invention does not require satellite joint calibration, which can minimize the dependence on human resources and site resources, and has small resource occupation and low evaluation cost.

[0080] (5) The evaluation results are of great value - the method used in the present invention can evaluate the high-frequency error, low-frequency error, error caused by the stability of the star sensor installation benchmark, and the measurement error of the star sensor itself in satellite attitude determination, clarify the contribution of various influencing factors to the accuracy of attitude determination, and lay the foundation for improving satellite design. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 It is a diagram of an embodiment of the present invention;

[0082] Figure 2 is a block diagram of the system composition principle of an embodiment of the present invention;

[0083] Figure 3 It is a schematic diagram of the installation structure of a star sensor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0084] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0085] In this embodiment, the number of star sensors configured is 3, namely star sensor A, star sensor B, and star sensor C. In practical applications, the method of the present invention can be used as long as the number of star sensors is greater than or equal to 2. Figure 1 and Figure 2 shown.

[0086] In S1, the onboard computer obtains the original quaternion observations of the three star sensors through the onboard data transmission bus, and solves the satellite attitude quaternion in real time, and regularly sends the original measurement quaternion Q of each star sensor with a time stamp to the satellite. A , Q B , Q CThe satellite attitude quaternion Q is transmitted to the onboard data transmission unit through the satellite data bus, and then transmitted to the ground data transmission receiving station through the satellite-to-ground data transmission link. The ground station transmits it to the ground data processing system through the ground data link.

[0087] In S2, the satellite inertial attitude angular velocity data VX, VY, and VZ are obtained through the ground measurement and control system. When the satellite's orbit is a stable orbit such as a circular orbit or an elliptical orbit, and the satellite is in a steady-state operation state without attitude maneuvers and orbital maneuvers, the satellite's attitude motion is stable, and the angular velocity change law of the star sensor optical axis pointing and the satellite's three-axis pointing in the inertial space is constant. The inertial attitude angular velocity VX of each axis of the satellite and the star sensor can also be obtained through theoretical calculations. i , VY i , VZ i ,i=A,B,C.

[0088] In S3, the angle method is used to analyze the onboard star sensor measurement data and attitude determination results, and separate the high-frequency part and the low-frequency trend item. The star sensor measurement coordinate system and the satellite body coordinate system are called this system, and the angle method is used to analyze the three-axis pointing data of this system, as follows:

[0089] The attitude quaternion at each moment is converted into the attitude conversion matrix from the J2000 inertial system to the current system. Each row of the matrix is ​​the vector representation of the X, Y, and Z axes of the current system in the J2000 system. The attitude matrix represented by the quaternion Q at time k is:

[0090]

[0091] in,

[0092]

[0093] In the above formula, the column vector is the vector part, q 0 is the scalar part, C(Q k ) is the attitude matrix at time k. The origin of the J2000 coordinate system is located at the center of mass of the Earth, the Z axis points to the J2000.0 mean celestial pole, and the X axis points to the J2000.0 mean vernal equinox.

[0094] Calculate the angle between the three axes of this system at the moment of contact.

[0095] ZGar k =arccos(Z k-1 ·Z k )

[0096] AngX k =arccos(X k-1 ·X k)

[0097] AngY k =arccos(Y k-1 ·Y k )

[0098] The angle curve contains three parts: the projection of the system's inertial angular velocity on the three axes, the low-frequency trend of the system's three-axis pointing error, and the high-frequency part of the system's three-axis pointing error. Next, these three items need to be separated one by one according to the satellite's orbit and attitude operation characteristics.

[0099] The angle curve is filtered by low-pass filtering, sliding window filtering and other filtering methods. The result is subtracted from the filtered curve by the original curve and then divided by Get the high frequency part of the pointing error.

[0100]

[0101]

[0102]

[0103] in, In this embodiment, when the number of satellite-configured star sensors is 3, HF STSA / HF STSB / HF STSC Indicates the high-frequency error of the A / B / C optical axis of the star sensor.

[0104] According to the satellite orbit and attitude operation rules, the three-axis theoretical inertial angular velocity of the system is calculated, and the theoretical inertial angular velocity is subtracted from the filtered curve to obtain the low-frequency trend term of the three-axis pointing error:

[0105]

[0106]

[0107]

[0108] Among them, VX / VY / VZ are the theoretical inertial angular velocity of the three axes of this system, T s is the data sampling period. For easy distinction, LF is used X / LF Y / LF Z LF represents the low-frequency trend of the satellite X / Y / Z axes. STSA / LF STSB / LF STSC Represents the low-frequency trend term of the star sensor A / B / C optical axis.

[0109] The method described in this step can be used to obtain the following axis angle curve and filtered curve:

[0110] The input for calculating the angle is set to the measured quaternion of two star sensors at the same time, and the optical axis angle curves of the two star sensors are obtained. After removing the mean (i.e. the nominal value of the angle), the optical axis angle change curve can be obtained. The optical axis angle change curves of any two star sensors can be obtained by the same method. In this embodiment, the optical axis angle change curves to be calculated are:

[0111] AngAB / AngAC / AngBC

[0112] The filtered curve is the low-frequency term of the angle of each star-sensing optical axis.

[0113]

[0114]

[0115]

[0116] When the input for calculating the angle is set to the measured quaternion of a certain star sensor and the satellite attitude quaternion at the same time, the angle curve between the optical axis of this star sensor and the Z axis of the satellite body is obtained. After removing the mean (i.e. the nominal value of the angle), the angle change curve is obtained. The same method is used to obtain the angle change curves between the optical axes of all star sensors and the Z axis of the star body.

[0117] In this embodiment, the angle change curves that need to be calculated are:

[0118] AngZA / AngZB / AngZC

[0119] The filtered curve is the low-frequency term of the angle of each star-sensing optical axis.

[0120]

[0121]

[0122]

[0123] In step S4, in step S3, the high frequency measurement error HF of the optical axis of each star sensor is calculated STSA / HF STSB / HF STSC And the satellite Z-axis attitude determination high frequency error HF Z , through the analysis of on-orbit data and engineering development experience, the evaluation standard of high-frequency error of satellite Z-axis attitude determination is proposed:

[0124]

[0125] Wherein, N is the number of star sensors involved in attitude determination. In this embodiment, N=3.

[0126] In HF Z and In the calculation process, the satellite attitude quaternion and the in-orbit measurement quaternion of each star sensor are used.

[0127] Evaluate the high-frequency accuracy of satellite attitude determination:

[0128] when When the satellite Z-axis attitude is determined, the high-frequency accuracy is within the normal range. Z The smaller the value, the higher the high frequency accuracy;

[0129] when When the satellite Z-axis attitude is determined, the high-frequency accuracy is poor. Z The larger the value, the worse the high frequency accuracy.

[0130] In S5, Figure 3 3a, 3b, and 3c show the installation diagrams of several common star sensors on satellites. In specific applications, the installation methods of star sensors include but are not limited to the methods given in the diagrams. According to the satellite mission requirements, the star sensor bracket is not necessary, and the star sensor can be directly installed on the satellite structure. From the analysis of the figure, it can be seen that the low-frequency trend term of the star sensor measurement error includes the low-frequency measurement error of the star sensor itself and the deformation of the star sensor installation benchmark, so there is:

[0131] LF AngAB =LF STSA +LF STSB +LF Flat

[0132] LF AngAC =LF STSA +LF STSC +LF Flat

[0133] LF AngBC =LF STSB +LF STSC +LF Flat

[0134] Among them, LF STSA , LF STSB , LF STSC is the low-frequency term in the measurement error of each star-sensing optical axis, LF AngAB , LF AngAC , LF AngBC is the low-frequency term of the change in the angle between the two star sensitivities, LF Flatis the deformation of the star sensor installation benchmark. The on-orbit deformation of the star sensor installation benchmark is obtained by the following formula.

[0135]

[0136] The widely used attitude determination methods based on star sensors are mainly divided into static determination algorithms (such as numerical solutions based on Newton iteration, TRIAD method and its improved algorithm, Euler-q method, QUEST method, least squares method MLS method, SVD method and FOAM method, etc.), dynamic state estimation algorithms (Kalman filter, extended Kalman filter, UKF method, predictive Kalman filter, nonlinear predictive filter, adaptive Kalman filter, recursive attitude prediction method, extended quaternion estimation, non-tracking filter, strong tracking filter, etc.), all of which are difficult to estimate and eliminate long-period low-frequency errors. Therefore, the attitude determination low-frequency error (LF) of the satellite + Z axis is difficult to estimate and eliminate. Z ) is an objective existence, and we should establish a Z An evaluation method is necessary.

[0137] Based on the above analysis, LF Z From the composition of

[0138]

[0139] in,

[0140] ——Evaluation criteria for low-frequency error in satellite +Z-axis attitude determination. During the calculation process, only the original quaternions of each star sensor on orbit are used, which characterizes the low-frequency accuracy of attitude determination that the satellite should achieve under the conditions of the configured star sensor measurement accuracy and installation reference deformation.

[0141] ω i ——The configurable weighted value is selected based on the actual attitude determination algorithm, the on-orbit illumination conditions of each star sensor, the thermal control environment, the installation orientation, etc., and represents the contribution of each star sensor's low-frequency error term to the satellite's total low-frequency error. According to engineering experience, in actual applications, the sum of the weighted values ​​( N is the number of star sensors involved in attitude determination and can be taken as 0.8 to 3.

[0142] The low-frequency determination accuracy that can actually be achieved by the satellite can be obtained by the following method.

[0143] Depend on

[0144] LF AngZA =LF STSA +LF Z +LF Flat

[0145] LF AngZB=LF STSB +LF Z +LF Flat

[0146] LF AngZC =LF STSC +LF Z +LF Flat

[0147] Combination From the expression of , we can see that

[0148]

[0149] In LF Z In the calculation process, the satellite attitude quaternion and the in-orbit measurement quaternion of each star sensor are used.

[0150] Therefore, the above method can be used to evaluate the low-frequency accuracy of satellite attitude determination:

[0151] when When the satellite Z-axis attitude is determined, the low-frequency accuracy is within the normal range. Z The smaller the value, the higher the low frequency accuracy;

[0152] when When the satellite Z-axis attitude is determined, the low-frequency accuracy is poor. Z The larger the value, the worse the low-frequency accuracy.

[0153] The contents not described in detail in the specification of the present invention belong to the common knowledge in the art.

Claims

1. A satellite attitude determination accuracy assessment method, characterized in that Here are the steps: Step S1, using a satellite onboard computer to collect raw measurement data of two or more star sensors installed on the satellite, and transmitting all the raw measurement data of the star sensors and the satellite attitude quaternion determined in real time by the onboard computer to the ground through a data transmission channel; Step S2, obtaining the satellite inertial attitude angular velocity and the inertial attitude angular velocity of the three axes of the star sensor during the evaluation period; Step S3, processing the original measurement data of the star sensor obtained in step S1 and the attitude quaternion determined in real time on the star, combining the information obtained in step S2, to obtain the high-frequency part and low-frequency trend item in the measurement error between the original measurement data of the star sensor and the attitude quaternion determined in real time on the star; In the step S3, the original measurement data of the on-board star sensor and the attitude determination result are processed by a fitting method or an angle method, and then a low-pass filter or a sliding window filter method is used to filter and separate the high-frequency part and the low-frequency trend item; The angle method is used to analyze the original measurement data of the on-board star sensor and the attitude determination results, and separate the high-frequency part and the low-frequency trend item, specifically: The attitude quaternion at each moment is converted into the attitude conversion matrix from the J2000 inertial system to the current system. Each row of the matrix is ​​the vector representation of the X, Y, and Z axes of the current system in the J2000 inertial system. The attitude matrix represented by the quaternion Q at moment k is: in, In the above formula, the column vector is the vector part, q0 is the scalar part, C(Q k ) is the posture matrix at time k, e x 、e y 、e z are the three-axis unit vectors of the reference rotation axis, φ is the rotation angle; The origin of the J2000 inertial system is located at the Earth's center of mass, the Z axis points to the J2000.0 mean celestial pole, and the X axis points to the J2000.0 mean vernal equinox; Calculate the angle curve of the three axes of this system at the same moment: AngZ k arccos(Z) k-1 ·Z k ) AngX k arccos(X) k-1 ·X k ) AngY k arccos(Y) k-1 ·Y k ) The angle curve contains three parts: the projection of the system's inertial angular velocity on the three axes, the low-frequency trend of the system's three-axis pointing error, and the high-frequency part of the system's three-axis pointing error. Next, these three items are separated one by one: The angle curve is filtered by low-pass filtering or sliding window filtering. The result of subtracting the filtered curve from the original curve is divided by Get the high-frequency part of the pointing error: Among them, AngX / AngY / AngZ represent the three-axis angle curve after filtering; According to the satellite orbit and attitude operation rules, the three-axis theoretical inertial angular velocity of the system is calculated, and the theoretical inertial angular velocity is subtracted from the filtered curve to obtain the low-frequency trend term of the three-axis pointing error: LF Z =AngZ-VZ*T s LF X =AngX-VX*T s Faculty of Medicine Y =AngY-VY*T s Among them, VX, VY, VZ are the theoretical inertial angular velocities of the three axes of this system, T s For data sampling period, use LF X , LF Y , LF Z Represents the low-frequency trend items of the satellite's X, Y, and Z axes; Step S4, processing the high-frequency part of the measurement error in step S3 to obtain a satellite attitude determination high-frequency error evaluation standard and evaluation result; Step S5, processing the low-frequency trend item of the measurement error in step S3, and obtaining the stability evaluation result of the star-sensing installation benchmark, the evaluation standard and evaluation result of the low-frequency error of satellite attitude determination.

2. A satellite attitude determination accuracy assessment method according to claim 1, characterized in that: In step S1, the star sensor may also be a star camera or a combination of a star sensor and a star camera.

3. A satellite attitude determination accuracy assessment method according to claim 1, characterized in that: In step S2, the satellite inertial attitude angular velocity is obtained by on-board telemetry or calculated according to the characteristics of the satellite orbit. Further, the inertial attitude angular velocity of the three axes is obtained in combination with the installation matrix of the star sensor in the satellite system. The star sensor installation matrix is ​​obtained through ground-based mechanical calibration or through on-orbit calibration of the star sensor.

4. A satellite attitude determination accuracy assessment method according to claim 1, characterized in that: The step S4 processes the high-frequency part of the measurement error to obtain the satellite attitude determination high-frequency error evaluation standard and evaluation result, which are specifically: According to the calculation, the high-frequency measurement error HF of the optical axis of each star sensor is obtained STSA HF STSB HF STSC And the satellite Z-axis attitude determination high frequency error HF Z , the evaluation criteria for high-frequency error in satellite Z-axis attitude determination are: Where N is the number of star sensors involved in attitude determination; Evaluate the high-frequency accuracy of satellite attitude determination: when When the satellite Z-axis attitude is determined, the high-frequency accuracy is within the normal range. Z The smaller the value, the higher the high frequency accuracy; when When the satellite Z-axis attitude is determined, the high-frequency accuracy is poor. Z The larger the value, the worse the high frequency accuracy.

5. A satellite attitude determination accuracy assessment method according to claim 4, characterized in that: The step S5 processes the low-frequency trend item of the measurement error to obtain the star sensor installation benchmark stability evaluation result, the satellite attitude determination low-frequency error evaluation standard and the evaluation result, specifically: When using the Samsung sensor for attitude determination, in, ——Evaluation criteria for low-frequency error of satellite +Z-axis attitude determination. During the calculation process, only the original quaternions of each star sensor on orbit are used, which represents the low-frequency accuracy of attitude determination that the satellite should achieve under the conditions of the configured star sensor measurement accuracy and installation benchmark deformation; ω i ——The configurable weighted value is selected based on the actual attitude determination algorithm, the on-orbit illumination conditions of each star sensor, the thermal control environment, the installation orientation, etc., and represents the contribution of the low-frequency error term of each star sensor to the total low-frequency error of the satellite; The low-frequency determination accuracy that can actually be achieved by the satellite is obtained by the following method: Depend on LF AngZA =LF STSA +LF Z +LF Flat LF AngZB =LF STSB +LF Z +LF Flat LF AngZC =LF STSC +LF Z +LF Flat Among them, LF STSA , LF STSB , LF STSC is the low-frequency term in the optical axis measurement error of each star sensor, LF Flat Install benchmark deformation for star sensors; Combination From the expression of , we can see that Evaluate the low-frequency accuracy of satellite attitude determination: when When the satellite Z-axis attitude is determined, the low-frequency accuracy is within the normal range. Z The smaller the value, the higher the low frequency accuracy; when When the satellite Z-axis attitude is determined, the low-frequency accuracy is poor. Z The larger the value, the worse the low-frequency accuracy.

6. A satellite attitude determination accuracy assessment method according to claim 5, characterized in that: Sum of weighted values Take 0.8~3, N is the number of star sensors involved in attitude determination.

7. A satellite attitude determination accuracy assessment system implemented based on the satellite attitude determination accuracy assessment method according to any one of claims 1 to 6, characterized in that include: Original measurement data acquisition module: using the satellite onboard computer, collects the original measurement data of all star sensors installed on the satellite, and transmits all the original measurement data of the star sensors and the satellite attitude quaternion determined in real time by the onboard computer to the ground through the data transmission channel; Three-axis attitude angular velocity acquisition module: acquires the inertial attitude angular velocity of the satellite's three axes and the inertial attitude angular velocity of each star sensor's three axes during the evaluation period; High-frequency and low-frequency separation module: Processes the original measurement data of the star sensor obtained in the original measurement data acquisition module and the attitude quaternion determined in real time on the satellite, and combines the information obtained in the three-axis attitude angular velocity acquisition module to obtain the high-frequency part and low-frequency trend item in the measurement errors of the two data; High-frequency processing evaluation module: processes the high-frequency part of the measurement error in the high-frequency and low-frequency separation module to obtain the evaluation criteria and results of the high-frequency error of satellite attitude determination; Low-frequency processing evaluation module: Processes the low-frequency trend items of the measurement errors in the high-frequency and low-frequency separation module to obtain the star sensor installation benchmark stability evaluation results, satellite attitude determination low-frequency error evaluation standards and evaluation results.

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