A data processing method to improve the speed of spacecraft precise orbit determination calculation

Abstract

The present invention discloses a data processing method for improving the speed of precise orbit determination calculation of spacecraft, comprising the following steps: step 1, configuring orbit determination software parameters; step 2, pre-calculating the earth-fixed system to earth-inertial system coordinate conversion matrix sequence and TDB-TT time difference sequence, and saving the calculation result sequence in memory; step 3, using interpolation method to obtain the pre-calculated results in memory. The present invention discloses a data processing method for improving the speed of precise orbit determination calculation of spacecraft, taking into account the functions that are repeatedly calculated and time-consuming in the program, such as pre-calculating the earth-fixed system to earth-inertial system conversion matrix and TDB-TT time difference, and saving the calculation result sequence in memory, and using interpolation method to reduce the time consumption of software calculation when using it.

Description

Technical Field

[0001] The present invention belongs to the technical field of spacecraft precise orbit determination methods, and in particular relates to a data processing method for improving the calculation speed of spacecraft precise orbit determination. Background Art

[0002] At present, deep space exploration missions such as lunar exploration, Mars exploration, and asteroid exploration are being actively carried out at home and abroad. The measurement model of deep space spacecraft orbit determination software requires iterative solution of light travel time and consideration of complex relativistic effect calculations, which requires multiple high-precision TT-TDB time conversions and Earth-inertial system-Earth-fixed system coordinate conversion calculations. This leads to the problem of slow calculation speed and low efficiency of the mainstream deep space orbit determination software in current engineering. Therefore, there is an urgent need to invent a data processing method to improve the calculation speed of orbit determination. Summary of the invention

[0003] The purpose of the present invention is to provide a data processing method for improving the calculation speed of spacecraft precise orbit determination, thereby solving the problems of slow calculation speed and low efficiency in existing deep space orbit determination software.

[0004] The technical solution adopted by the present invention is: a data processing method for improving the speed of spacecraft precise orbit determination calculation, comprising the following steps:

[0005] Step 1: Configure orbit determination software parameters;

[0006] Step 2: Pre-calculate the coordinate transformation matrix sequence from the Earth-fixed system to the Earth-inertial system and the TDB-TT time difference sequence, and save the calculation result sequence in the memory;

[0007] Step 3: Use interpolation method to obtain the pre-calculated results in memory.

[0008] The present invention is also characterized in that:

[0009] The orbit determination software parameters configured in step 1 include the start and end times of the orbit determination software calculation scenario and the time step of the saved sequence.

[0010] The calculation of the coordinate transformation matrix sequence from the earth fixed system to the earth inertial system in step 2 specifically includes: the length N of the coordinate transformation matrix sequence sorted in time series by formula (1):

[0011]

[0012] In formula (1), t start and t endare the start and end times of the scene calculated by the orbit determination software, and d is the time step for saving the sequence; and these matrix sequences are saved in memory. The sequence is managed using a 10×N two-dimensional pointer, which indexes the TT relative time relative to the start time of the software and the 9 elements of the 3×3 coordinate transformation matrix.

[0013] The calculation of the TDB-TT time difference sequence in step 2 specifically includes: calculating the length N of the TDB time sequence sorted by time sequence by formula (2), and saving the sequence in the memory. The sequence is managed by a 3×N two-dimensional pointer, which respectively indexes the TT relative time sequence, the TDB relative time sequence and the TDB-TT time difference sequence relative to the software start time.

[0014] In step 3, the location of the data to be interpolated in the memory is calculated by formula (2):

[0015]

[0016] Among them, ceil() represents the rounding operation, t is the interpolation time, t0 is the start time of the sequence, and d is the time step for saving the sequence; take eight points I-4, I-3, I-2, I-1, I, I+1, I+2, and I+3, and use the 7th Lagrange interpolation method to obtain a coordinate transformation matrix of 9 elements.

[0017] In step 3, the location of the interpolated data in the memory is calculated by formula (2), and eight points, I-4, I-3, I-2, I-1, I, I+1, I+2, and I+3, are taken. The TDB-TT time difference is obtained by using the 7th Lagrange interpolation method.

[0018] The beneficial effects of the present invention are as follows: a data processing method for improving the speed of precise orbit determination calculation of a spacecraft takes into account the pre-calculation of functions such as the Earth-fixed system to Earth-inertial system conversion matrix and the TDB-TT time difference, which are repeatedly calculated and time-consuming in the program, and saves the calculation result sequence in the memory, and adopts the interpolation method when in use to reduce the time consumption of software calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a flow chart of a data processing method for improving the calculation speed of precise orbit determination of a spacecraft. DETAILED DESCRIPTION

[0020] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] The present invention provides a data processing method for improving the speed of spacecraft precise orbit determination calculation, such as Figure 1 As shown, the following steps are included:

[0022] 1. Configure orbit determination software parameters

[0023] Configure the start and end time of the orbit determination software to calculate the scene, the time step of the saved sequence, and other information. For example, set the time step of the Earth-fixed to Earth-inertial coordinate conversion matrix sequence to 1 second, and set the time step of the TDB-TT time difference sequence to 100 seconds.

[0024] 2. Calculate the coordinate transformation matrix sequence from the Earth-fixed system to the Earth-inertial system

[0025] The software is used to calculate the start and end time of the scene and the sequence step length, and the length N of the coordinate transformation matrix sequence sorted by time series is calculated according to formula (1).

[0026]

[0027] Among them, t start and t end is the start and end time of the software calculation scene, and d is the sequence step. Using the IAU2000 or IAU2006 earth pointing model, all transformation matrices within this time range are calculated and saved in the memory pointed to by the 10×N two-dimensional pointer.

[0028] 3. Calculate TDB-TT time difference series

[0029] Use the software to calculate the start and end time of the scene and the sequence step length, and calculate the required number of steps according to formula (1).

[0030] Using the SOFA precise time conversion model, all time differences within the time range are calculated and saved together with the TT and TDB times used for indexing in the memory pointed to by a 3×N two-dimensional pointer.

[0031] 4. Interpolation uses the Earth-fixed to Earth-inertial coordinate conversion matrix

[0032] When a point t to be interpolated is given, formula (2) is used to quickly index the memory area close to the interpolation point:

[0033]

[0034] Among them, ceil() means rounding up, t is the interpolation time, t0 is the start time of the sequence, and d is the time step of the saved sequence; take the 8 points before and after, use the 7th Lagrange method, and interpolate the 9 elements of the coordinate transformation matrix at the interpolation point in sequence. When the coordinate transformation matrix from the Earth Inertial System to the Earth Fixed System is needed, just transpose the original matrix.

[0035] 5. Interpolation using TDB-TT time difference

[0036] When the interpolation point t is given, use formula (2) to quickly index the memory area close to the interpolation point, take the 8 points before and after, and use the 7th Lagrange method to interpolate the TDB-TT time difference at the interpolation point. When converting from TT to TDB, use the TT sequence index; when converting from TDB to TT, use the TDB sequence index.

[0037] Through the above manner, a data processing method for improving the speed of spacecraft precise orbit determination calculation is provided in the present invention. It takes into account the pre-calculation of the earth-fixed system to earth-inertial system conversion matrix and TDB-TT time difference and other functions that are repeatedly calculated and time-consuming in the program, and saves the calculation result sequence in the memory. When in use, the interpolation method is used to reduce the time consumption of software calculation.

[0038] Example

[0039] The improvement of algorithm calculation efficiency is illustrated by taking a precise orbit of a Mars satellite as an example. A certain orbit determination mission uses three days of ground-based station observation data, including 200,000 two-way ranging and velocity measurement observation data. The nonlinear least squares batch processing method is used to iterate 20 times to calculate the precise orbit elements.

[0040] The efficiency of this method is shown in the following table.

[0041]

Claims

1. A data processing method for improving the speed of spacecraft precise orbit determination calculation, characterized in that: The following steps are involved: Step 1: Configure the orbit determination software parameters, including the start and end time of the orbit determination software calculation scene and the time step of the saved sequence; Step 2: Pre-calculate the coordinate transformation matrix sequence from the Earth-fixed system to the Earth-inertial system and the TDB-TT time difference sequence, and save the calculation result sequence in the memory; The calculation of the coordinate transformation matrix sequence from the earth fixed system to the earth inertial system specifically includes: calculating the length N of the coordinate transformation matrix sequence sorted in time series by formula (1): （1） In formula (1), and is the start and end time of the scene calculated by the orbit determination software, is the sequence step length; and the calculated coordinate transformation matrix sequence is saved in the memory. The sequence is managed by a 10×N two-dimensional pointer, which indexes the TT relative time relative to the software start time and the 9 elements of the 3×3 coordinate transformation matrix respectively; Calculating the TDB-TT time difference sequence specifically includes: calculating the length N of the TDB time sequence sorted by the time sequence by formula (1), and saving the calculated TDB time sequence in the memory. The sequence is managed by a 3×N two-dimensional pointer, which respectively indexes the TT relative time sequence, the TDB relative time sequence and the TDB-TT time difference sequence relative to the software start time; Step 3: Use interpolation method to obtain the pre-calculated results in memory; The location of the data to be interpolated in the memory is calculated by formula (2): （2） in, Indicates rounding up operation. is the interpolation moment, is the start time of the sequence, is the time step of the saved sequence; Eight points are interpolated in sequence using the 7th Lagrange interpolation method to obtain the 9 elements of the coordinate transformation matrix at the interpolation point; Pick At eight points, the TDB-TT time difference is obtained using the seventh-order Lagrange interpolation method.

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