Method for simulating high-frequency and high-precision attitude of satellite on ground based on three-axis gyroscope

Abstract

The invention provides a method for simulating high-frequency and high-precision attitudes of satellites on the ground based on a three-axis gyroscope, which is used for solving the problems that the updating frequency of feedback data is low, the control requirement of a control system for high-precision and long-time target tracking cannot be met, and the accuracy of the feedback data is low due to the fact that the attitude data output by the existing satellites is low and the accuracy is difficult to reach 1 ''. And no method for acquiring the high-frequency and high-precision attitude of the satellite indoors exists at present. According to the method for simulating the high-frequency and high-precision attitude of the satellite on the ground based on the three-axis gyroscope, the three-axis gyroscope is fixedly installed on a satellite attitude simulator, a conversion matrix from an earth coordinate system to a satellite attitude simulator coordinate system is solved, and then a ground velocity component under the satellite attitude simulator coordinate system is obtained; and the high-frequency accurate attitude of the satellite is obtained through the difference value between the angular rate of the three-axis gyroscope and the ground velocity component under the coordinate system of the satellite attitude simulator, so that the technical blank of obtaining the high-frequency and high-precision attitude of the satellite indoors is filled, the economic cost is low, and no hardware transformation loss and risk exist.

Description

Technical Field

[0001] The present invention relates to a method for acquiring satellite attitude, and in particular to a method for simulating high-frequency and high-precision satellite attitude on the ground based on a three-axis gyroscope. Background Art

[0002] The control requirements of the satellite itself do not require obtaining its own high-frequency and high-precision attitude. However, since the country has put forward the high-precision tracking requirement of no miss-margin and long integration time for the space-based optoelectronic turntable for the first time, the payload installed on the satellite needs to avoid satellite disturbances during the long integration time while tracking dynamic targets with high precision. At present, the tracking of moving targets with miss-margin can eliminate the disturbance of the satellite through the closed loop of the miss-margin itself. For low-precision tracking with a large field of view, if the disturbance of the satellite itself is not large, it does not need to be corrected. However, for the tracking of moving targets with no miss-margin with picosecond tracking stability and a long camera integration time (more than ten to twenty seconds), it is necessary not only to correct the disturbance of the satellite, but also to make very precise corrections. This requires knowing the real-time high-frequency and high-precision attitude of the satellite in order to eliminate the disturbance of the satellite to the payload itself as accurately as possible.

[0003] Because the attitude data output by the satellite itself is provided by star sensors, the frequency of the satellite's own attitude data is relatively low (4-10Hz) and the accuracy is difficult to achieve 1", resulting in a low feedback data update frequency, which cannot meet the control system's requirements for high-precision and long-term target tracking. In addition, although existing satellites are equipped with fiber optic gyroscopes, they are generally used for velocity measurement. However, the process of obtaining high-frequency and high-precision satellite attitude requires step-by-step verification from indoor to outdoor observation. However, the industry currently does not have a method for obtaining high-frequency and high-precision satellite attitude indoors. Summary of the Invention

[0004] The purpose of the present invention is to address the technical problems that the attitude data output by existing satellites is low in frequency and the accuracy is difficult to reach 1", resulting in a low update frequency of feedback data, which cannot meet the control requirements of the control system for high-precision and long-term target tracking. In addition, there is currently no technical method for obtaining high-frequency and high-precision satellite attitude indoors in the industry. Therefore, a method for simulating high-frequency and high-precision satellite attitude on the ground based on a three-axis gyroscope is proposed.

[0005] In order to achieve the above object, the technical solution provided by the present invention is as follows:

[0006] A method for simulating a high-frequency and high-precision attitude of a satellite on the ground based on a three-axis gyroscope is characterized in that it includes the following steps:

[0007] Step 1: Set up a satellite attitude simulator and fix the three-axis gyroscope on the satellite attitude simulator; establish a satellite attitude simulator coordinate system and a three-axis gyroscope coordinate system;

[0008] Step 2: calibrate the relationship between the satellite attitude simulator and the true north of the earth, and obtain the angle θ between the X-axis zero position of the satellite attitude simulator coordinate system and the true north of the earth;

[0009] Step 3, establishing the relationship between the earth coordinate system and the satellite attitude simulator coordinate system;

[0010] Step 3.1: Rotate the Earth coordinate system 90° clockwise around its Y axis, then rotate it clockwise around its new X axis by (90°-N°), where N° is the latitude of the Earth where the satellite attitude simulator is located, and then rotate it 90° clockwise around its new Z axis to obtain the ideal coordinate system of the Earth coordinate system at the location of the satellite attitude simulator.

[0011] Step 3.2, after rotating the Earth coordinate system clockwise around its new Z axis by an angle θ, calculate the transformation matrix from the Earth coordinate system to the satellite attitude simulator coordinate system;

[0012] Step 4: According to the transformation matrix from the Earth coordinate system to the satellite attitude simulator coordinate system, the vector of the Earth's rotation angular velocity in the Earth coordinate system is transformed into the satellite attitude simulator coordinate system to obtain the ground velocity component in the satellite attitude simulator coordinate system;

[0013] Step 5, establishing the relationship between the three-axis gyro coordinate system and the satellite attitude simulator coordinate system;

[0014] Step 5.1, measure the three Euler angles α, β, and γ between the three-axis gyro coordinate system and the satellite attitude simulator coordinate system, and calculate the transformation matrix from the three-axis gyro coordinate system to the satellite attitude simulator coordinate system based on the three Euler angles α, β, and γ;

[0015] Step 5.2, convert the three-axis gyro angular rate in the three-axis gyro coordinate system to the satellite attitude simulator coordinate system through the conversion matrix from the three-axis gyro coordinate system to the satellite attitude simulator coordinate system, and obtain the three-axis gyro angular rate in the satellite attitude simulator coordinate system;

[0016] Step 6: When the satellite attitude simulator simulates the rotation of the satellite, the difference between the three-axis gyro angular rate and the ground speed component in the satellite attitude simulator coordinate system is calculated, and the difference is integrated to obtain the high-frequency precise attitude of the satellite.

[0017] Furthermore, in step 1, the three-axis gyroscope is a three-axis fiber optic gyroscope, which is installed at the top of the satellite attitude simulator, and the installation surface of the three-axis gyroscope is the plane where the X-axis and Y-axis of the satellite attitude simulator coordinate system are located.

[0018] Furthermore, step 6 is specifically as follows:

[0019] When the satellite attitude simulator simulates satellite rotation, the high-frequency and precise attitude of the satellite is solved by the following formula:

[0020]

[0021] Among them, θ fogx ,θ fogy ,θ fogz are the three Euler angles corresponding to the high-frequency precise attitude of the satellite, t0 and t1 are the start and end times of integration respectively, t is the time for the satellite attitude simulator to simulate the satellite rotation, ω ex 、ω ey 、ω ez are the ground velocity components corresponding to the X-axis, Y-axis, and Z-axis in the satellite attitude simulator coordinate system; f yx 、f yy 、f yz They are the three-axis gyro angular rates corresponding to the X-axis, Y-axis, and Z-axis in the satellite attitude simulator coordinate system.

[0022] The beneficial effects of the present invention compared to the prior art are as follows:

[0023] 1. The present invention provides a method for simulating the high-frequency and high-precision attitude of a satellite on the ground based on a three-axis gyroscope. The three-axis gyroscope is fixedly installed on a satellite attitude simulator, and the angle between the X-axis zero position of the satellite attitude simulator coordinate system and the true north of the earth is obtained. The conversion matrix from the earth coordinate system to the satellite attitude simulator coordinate system is obtained in combination with the angle, and the ground speed component in the satellite attitude simulator coordinate system is obtained. The high-frequency and precise attitude of the satellite is obtained by the difference between the angular rate of the three-axis gyroscope and the ground speed component in the satellite attitude simulator coordinate system, which fills the technical gap in obtaining the high-frequency and high-precision attitude of satellites indoors.

[0024] 2. The present invention can be implemented by only modifying the software, which has low economic cost and no hardware modification loss or risk, thereby improving economy and operability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the installation of a three-axis gyroscope and a satellite attitude simulator in step 1 of a method for simulating a high-frequency and high-precision satellite attitude on the ground based on a three-axis gyroscope according to the present invention;

[0026] Figure 2 This is a schematic diagram of the relationship between the earth coordinate system and the satellite attitude simulator coordinate system in step 3.1 of the method for simulating high-frequency and high-precision satellite attitude on the ground based on a three-axis gyroscope of the present invention. DETAILED DESCRIPTION

[0027] In order to make the advantages and features of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] A method for simulating a high-frequency and high-precision attitude of a satellite on the ground based on a three-axis gyroscope specifically comprises the following steps:

[0029] Step 1: Since the indoor environment does not have the conditions for using a star sensor when conducting a ground simulation experiment indoors, the present invention sets up a satellite attitude simulator and establishes a satellite attitude simulator coordinate system OXYZ, and fixes a three-axis gyroscope on the satellite attitude simulator so that the output angle of the satellite attitude simulator replaces the output angle of the star sensor. In this embodiment, the three-axis gyroscope is a three-axis fiber optic gyroscope, which is fixedly connected to the satellite attitude simulator when installed. Figure 1 As shown, the three-axis gyro is installed at the top of the satellite attitude simulator, and its installation surface is the plane where the X-axis and Y-axis of the satellite attitude simulator coordinate system are located. After the three-axis gyro is installed, the three-axis gyro coordinate system O is established. f X f Y f Z f .

[0030] Step 2: calibrate the relationship between the satellite attitude simulator and the true north of the earth, and obtain the angle θ between the X-axis zero position of the satellite attitude simulator coordinate system and the true north of the earth.

[0031] Step 3: Establish the relationship between the Earth coordinate system and the satellite attitude simulator coordinate system.

[0032] Step 3.1, define the earth coordinate system as O e X e Y e Z e ,like Figure 2 As shown, the earth coordinate system O e X e Y e Z e Around Y e The axis rotates 90° clockwise and then moves around the new X e The axis rotates clockwise (90°-N), where N is the latitude of the Earth where the satellite attitude simulator is located, and then rotates around the new Z e The axis is rotated 90° clockwise to obtain the ideal coordinate system of the Earth coordinate system at the location of the satellite attitude simulator. Therefore, the transformation matrix from the Earth coordinate system to the ideal satellite attitude simulator coordinate system is Obtained by the following formula:

[0033]

[0034] Where, Tz(90°)=[cos(90°)sin(90°)0;-sin(90°)cos(90°)0;0 0 1];

[0035] Ty(90°)=[cos(90°)0-sin(90°); 0 1 0; sin(90°)0cos(90°)];

[0036] Tx(90°-N)=[1 0 0; 0cos(90°-N)sin(90°-N); 0-sin(90°-N)cos(90°-N)];

[0037] Step 3.2, reorient the Earth coordinate system around the new Z e After the axis rotates clockwise by an angle θ, the transformation from the earth coordinate system to the satellite attitude simulator coordinate system is realized, and the transformation matrix from the earth coordinate system to the satellite attitude simulator coordinate system is obtained. The specific formula is as follows:

[0038]

[0039] Step 4: Convert the vector of the Earth's rotational angular velocity in the Earth coordinate system to the satellite attitude simulator coordinate system to obtain the ground velocity component in the satellite attitude simulator coordinate system; let the vector of the Earth's rotational angular velocity in the Earth coordinate system be L; according to the conversion matrix from the Earth coordinate system to the satellite attitude simulator coordinate system Convert the vector L of the earth's rotational angular velocity in the earth coordinate system to the satellite attitude simulator coordinate system to obtain the ground velocity component L in the satellite attitude simulator coordinate system y , which is expressed as follows:

[0040]

[0041] The ground velocity component L in the satellite attitude simulator coordinate system y Written in scalar form, the ground velocity components ω corresponding to the X-axis, Y-axis, and Z-axis in the satellite attitude simulator coordinate system can be obtained ex 、ω ey 、ω ez .

[0042] Step 5: Establish the relationship between the three-axis gyro coordinate system and the satellite attitude simulator coordinate system.

[0043] Step 5.1, first measure the Euler angles α, β, and γ of the three-axis gyro coordinate system around the satellite attitude simulator coordinate system. Among them, α is the angle of the three-axis gyro coordinate system around the X-axis of the satellite attitude simulator coordinate system, β is the angle of the three-axis gyro coordinate system around the Y-axis of the satellite attitude simulator coordinate system, and γ is the angle of the three-axis gyro coordinate system around the Z-axis of the satellite attitude simulator coordinate system. Then calculate the transformation matrix from the three-axis gyro coordinate system to the satellite attitude simulator coordinate system using the following formula:

[0044]

[0045] Tz(γ)=[cos(γ)sin(γ)0; -sin(γ)cos(γ)0; 0 0 1];

[0046] Ty(β)=[cos(β)0-sin(β); ​​0 1 0; sin(β)0cos(β)];

[0047] Tx(α)=[1 0 0; 0cos(α)sin(α); 0-sin(α)cos(α)].

[0048] Step 5.2, set the three-axis angular rate of the three-axis gyroscope in the three-axis gyroscope coordinate system Transformation matrix from the three-axis gyro coordinate system to the satellite attitude simulator coordinate system The three-axis gyroscope angular rate in the three-axis gyroscope coordinate system Convert to the satellite attitude simulator coordinate system to obtain the three-axis gyro angular rate in the satellite attitude simulator coordinate system Its expression is as follows:

[0049]

[0050] The three-axis gyro angular rate in the satellite attitude simulator coordinate system Written in scalar form, the three-axis gyro angular rate f corresponding to the X-axis, Y-axis, and Z-axis in the satellite attitude simulator coordinate system can be obtained yx 、f yy 、f yz .

[0051] Step 6: When the satellite attitude simulator simulates the rotation of the satellite, the three-axis gyro angular rate in the satellite attitude simulator coordinate system is That is, the angular rate measured by the three-axis gyroscope is projected onto the satellite attitude simulator coordinate system. The ground velocity component L in the satellite attitude simulator coordinate system is y It is the value of the Earth's rotational angular velocity projected onto the satellite attitude simulator coordinate system.

[0052] Therefore, the high-frequency and precise attitude of the satellite can be obtained by solving the difference between the three-axis gyro angular rate and the ground speed component corresponding to the X-axis, Y-axis, and Z-axis in the satellite attitude simulator coordinate system by the following formula and integrating the difference.

[0053]

[0054] Among them, θ fogx ,θ fogy ,θ fogzare the three Euler angles corresponding to the high-frequency precise attitude of the satellite; t0 and t1 are the start and end times of integration respectively, and t is the time for the satellite attitude simulator to simulate the satellite rotation.

[0055] The above description is only used to illustrate the technical solution of the present invention, rather than to limit it. For ordinary professional and technical personnel in this field, the specific technical solutions recorded in the above embodiments can be modified, or some of the technical features therein can be replaced by equivalents. These modifications or replacements do not cause the essence of the corresponding technical solution to deviate from the scope of the technical solution protected by the present invention.

Claims

1. A method for simulating high-frequency and high-precision satellite attitude on the ground based on a three-axis gyroscope, characterized in that: The following steps are involved: Step 1: Set up a satellite attitude simulator and fix the three-axis gyroscope on the satellite attitude simulator; establish a satellite attitude simulator coordinate system and a three-axis gyroscope coordinate system; Step 2: Calibrate the relationship between the satellite attitude simulator and the true north of the earth, and obtain the angle between the X-axis zero position of the satellite attitude simulator coordinate system and the true north of the earth. Step 3, establishing the relationship between the earth coordinate system and the satellite attitude simulator coordinate system; Step 3.1: Rotate the Earth coordinate system 90° clockwise around its Y axis, then rotate it clockwise around its new X axis by (90°-N°), where N° is the latitude of the Earth where the satellite attitude simulator is located, and then rotate it 90° clockwise around its new Z axis to obtain the ideal coordinate system of the Earth coordinate system at the location of the satellite attitude simulator. Step 3.2, rotate the Earth coordinate system clockwise around its new Z axis by an angle Finally, calculate the transformation matrix from the earth coordinate system to the satellite attitude simulator coordinate system; Step 4: According to the transformation matrix from the Earth coordinate system to the satellite attitude simulator coordinate system, the vector of the Earth's rotation angular velocity in the Earth coordinate system is transformed into the satellite attitude simulator coordinate system to obtain the ground velocity component in the satellite attitude simulator coordinate system; Step 5, establishing the relationship between the three-axis gyro coordinate system and the satellite attitude simulator coordinate system; Step 5.1, measure the three Euler angles α, β, and γ between the three-axis gyro coordinate system and the satellite attitude simulator coordinate system, and calculate the transformation matrix from the three-axis gyro coordinate system to the satellite attitude simulator coordinate system based on the three Euler angles α, β, and γ; Step 5.2, convert the three-axis gyro angular rate in the three-axis gyro coordinate system to the satellite attitude simulator coordinate system through the conversion matrix from the three-axis gyro coordinate system to the satellite attitude simulator coordinate system, and obtain the three-axis gyro angular rate in the satellite attitude simulator coordinate system; Step 6: When the satellite attitude simulator simulates the rotation of the satellite, the difference between the three-axis gyro angular rate and the ground speed component in the satellite attitude simulator coordinate system is calculated, and the difference is integrated to obtain the high-frequency precise attitude of the satellite.

2. The method of simulating high-frequency and high-precision satellite attitude on the ground based on a three-axis gyroscope according to claim 1, characterized in that: In step 1, the three-axis gyroscope is a three-axis fiber optic gyroscope, which is installed at the top of the satellite attitude simulator. The installation surface of the three-axis gyroscope is the plane where the X-axis and Y-axis of the satellite attitude simulator coordinate system are located.

3. The method of simulating high-frequency and high-precision satellite attitude on the ground based on a three-axis gyroscope according to claim 1 or 2, characterized in that: Step 6 is as follows: When the satellite attitude simulator simulates satellite rotation, the high-frequency and precise attitude of the satellite is solved by the following formula: in, are the three Euler angles corresponding to the high-frequency precise attitude of the satellite, t0 and t1 are the start and end times of integration respectively, t is the time for the satellite attitude simulator to simulate the satellite rotation, ω ex 、ω ey 、ω ez are the ground velocity components corresponding to the X-axis, Y-axis, and Z-axis in the satellite attitude simulator coordinate system; f yx 、f yy 、f yz They are the three-axis gyro angular rates corresponding to the X-axis, Y-axis, and Z-axis in the satellite attitude simulator coordinate system.

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