Fault Tolerant Control Method and System for Angle Measurement Signal Grounding Fault of Biaxial Windsurfing Board Driving Mechanism

Abstract

Fault Tolerant Control Method and System for the Angle Measurement Signal Grounding Fault of the Biaxial Windsurfing Drive Mechanism, including: Denote the measured value of the rotation angle of the B-axis collected in each control cycle as a1, and denote the rotation angle of the B-axis corresponding to the number of driving steps of the B-axis as b1. Set the initial value of b1 equal to the value of a1 read for the first time after power-on. Then, in each control cycle, calculate the difference between the a1 value collected in this control cycle and the b1 value calculated in this control cycle. Judge the working state of the spacecraft's windsurfing drive mechanism according to the difference. If the absolute value of the difference is less than the fault threshold, the spacecraft's windsurfing drive mechanism is working normally. At this time, record the measured value of the rotation angle of the B-axis in this control cycle as the historical value of the rotation angle of the B-axis, denoted as A1. If the absolute value of the difference is greater than the fault threshold, the B-axis stops rotating in this control cycle, and at the same time, A1 is not updated. The present invention establishes an on-board autonomous diagnosis and control strategy, which can quickly solve the problem of short-term faults in the B-axis rotation angle measurement signal.

Description

Technical Field

[0001] The present invention belongs to the technical field of spacecraft attitude control, and particularly relates to a fault-tolerant control method and system for the ground connection fault of the angle measurement signal of a two-axis solar panel drive mechanism, aiming to solve the problem of the ground connection fault of the angle measurement signal of the distal axis of the two-axis solar panel drive mechanism. Background Art

[0002] With the development of space technology, the requirements of space missions have changed greatly. The selection of the operating orbit of spacecraft has become more and more complex. Many spacecraft need to operate in non-sun-synchronous orbits. For such orbits, the traditional single-axis solar panel drive mechanism cannot align with the sun throughout the orbit period. To address this issue, there are usually two strategies. One is to adopt the strategy of combining body offset with single-axis solar panel control, which has certain limitations on the operation of payloads. The other is to adopt a two-axis solar panel drive mechanism, which not only ensures that the solar panel can track the sun in real time but also meets the requirement of three-axis stability for satellite earth orientation.

[0003] For a two-axis solar panel drive mechanism, we define the axis close to the spacecraft body as the proximal axis (hereinafter referred to as the A axis), and the axis far from the spacecraft as the distal axis (hereinafter referred to as the B axis). The A axis rotates 360 degrees to track the sun, and the B axis swings at a limited position to track the sun. Usually, the rotation angle measurement signal of the B axis needs to be transmitted to the spacecraft through the slip ring of the A axis and serves as the input signal for controlling the B axis of the solar panel drive mechanism. As the operation time of the spacecraft becomes longer, especially for some spacecraft operating beyond their designed lifespan, due to the accumulation of slip ring abrasives, the rotation angle measurement signal of the B axis may experience short-term ground connection failure when the A axis rotates to certain angular intervals. Outside this angular interval, the rotation angle measurement signal of the B axis can be used normally again.

[0004] For the current control strategy of the two-axis solar panel drive mechanism, after determining the fault of the rotation angle measurement signal of the B axis, it switches to the backup rotation angle measurement signal of the B axis, and the system loses redundant backup. Summary of the Invention

[0005] The present invention proposes a fault-tolerant control method and system for the ground connection fault of the angle measurement signal of a two-axis solar panel drive mechanism to solve the problem of short-term failure of the rotation angle measurement signal of the distal axis of the spacecraft.

[0006] The present invention proposes a fault-tolerant control method for the ground connection fault of the angle measurement signal of a two-axis solar panel drive mechanism, including:

[0007] For a spacecraft with a two-axis solar panel, the axis close to the spacecraft body is taken as the A axis, and the axis far from the spacecraft is taken as the B axis; the rotation angle measurement value of the B axis collected in each control cycle is denoted as a1, and the number of driving steps of the B-axis motor in this control cycle is recorded, and the rotation angle of the B axis corresponding to the number of driving steps of the B-axis motor is denoted as b1;

[0008] First, set the initial value of b1 equal to the value of a1 read for the first time after power-on. In each control period, subtract the value of a1 collected in this control period from the value of b1 in this control period to obtain a difference value.

[0009] Judge the working state of the spacecraft solar panel drive mechanism according to the difference value. If the absolute value of the difference value is less than the fault threshold, it is determined that the spacecraft solar panel drive mechanism is working normally; if the difference value is greater than the fault threshold for n1 consecutive times, it is determined that there is a fault in the B-axis rotation angle measurement signal. At this time, reassign the value of b1 with the historical value A1 of the B-axis rotation angle, and at the same time use b1 as the input signal for B-axis rotation control.

[0010] After it is determined that there is a fault in the B-axis rotation angle measurement signal, continue to continuously judge the difference value between a1 and b1 in each control period. When the absolute value of the difference value is less than the fault threshold for n2 consecutive times, it is determined that the fault of the B-axis rotation angle measurement signal is eliminated. At this time, use the current B-axis rotation angle measurement value a1 as the input signal for B-axis rotation control.

[0011] Furthermore, if the difference value is greater than the fault threshold for n1 consecutive times, it is determined that there is a fault in the B-axis rotation angle measurement signal, which specifically includes:

[0012] Set a first counter T1, and the first counter T1 records the number of times the difference value is continuously greater than the fault threshold; set a second counter T2, and the second counter T2 records the number of times the difference value is continuously less than the fault threshold.

[0013] If it is detected that the absolute value of the difference value is greater than the fault threshold, the first counter T1 is incremented by 1.

[0014] If it is detected that the absolute value of the difference value is less than the fault threshold, the second counter T2 is incremented by 1.

[0015] If the value of T1 is less than n1, the B-axis stops rotating in this control period and A1 is not updated.

[0016] If the value of T1 is greater than n1, it is determined that there is a fault in the B-axis rotation angle measurement signal, and at the same time the second counter T2 is cleared.

[0017] Furthermore, when continuously judging the difference value between a1 and b1 in the control period, when the absolute value of the difference value is less than the fault threshold for n2 consecutive times, the fault of the B-axis rotation angle measurement signal is eliminated, which specifically includes:

[0018] If it is detected that the absolute value of the difference is greater than the fault threshold, the first counter T1 is incremented by 1; if it is detected that the absolute value of the difference is less than the fault threshold, the second counter T2 is incremented by 1, and the first counter T1 is cleared. If it is detected that the absolute value of the difference is greater than the fault threshold, the second counter T2 is cleared;

[0019] When the second counter T2 is greater than n2, it is determined that the fault of the B-axis rotation angle measurement signal is eliminated.

[0020] The present invention also provides an angle measurement signal grounding fault tolerance control system for a dual-axis solar panel drive mechanism, which includes: an initialization module and a fault judgment and processing module, wherein,

[0021] Initialization module: Set the initial value of b1, and the initial value of b1 is equal to the value of a1 read for the first time after power-on. In each control cycle, the difference between the value of a1 collected in this control cycle and the value of b1 in this control cycle is obtained; wherein, for a spacecraft with a dual-axis solar panel, the axis closer to the spacecraft body is used as the A-axis, and the axis away from the spacecraft is used as the B-axis; the measured value of the B-axis rotation angle collected in each control cycle is recorded as a1, and the number of steps of the B-axis motor drive in this control cycle is recorded, and the B-axis rotation angle corresponding to the number of steps of the B-axis drive is recorded as b1, and the last measured value of the B-axis rotation angle in this control cycle is used as the B-axis rotation angle historical value A1;

[0022] Fault judgment and processing module: Judge the working state of the spacecraft solar panel drive mechanism according to the difference. If the absolute value of the difference is less than the fault threshold, it is determined that the spacecraft solar panel drive mechanism is working normally;

[0023] If the difference is greater than the fault threshold for n1 consecutive times, it is determined that a fault has occurred in the B-axis rotation angle measurement signal. At this time, the B-axis rotation angle historical value A1 is used to reassign the value of b1, and at the same time, b1 is used as the input signal for B-axis rotation control;

[0024] After it is determined that a fault has occurred in the B-axis rotation angle measurement signal, the difference between a1 and b1 is continuously judged within the control cycle. When the absolute value of the difference is less than the fault threshold for n2 consecutive times, it is determined that the fault of the B-axis rotation angle measurement signal is eliminated. At this time, the current measured value a1 of the B-axis rotation angle is used as the input signal for B-axis rotation control;

[0025] Furthermore, if the difference is greater than the fault threshold for n1 consecutive times, the fault judgment and processing module determines that a fault has occurred in the B-axis rotation angle measurement signal, specifically including:

[0026] Set a first counter T1, where the first counter T1 records the number of times the difference is continuously greater than the fault threshold; set a second counter T2, where the second counter T2 records the number of times the difference is continuously less than the fault threshold;

[0027] If it is detected that the absolute value of the difference is greater than the fault threshold, then the first counter T1 is incremented by 1,

[0028] If it is detected that the absolute value of the difference is less than the fault threshold, then the second counter T2 is incremented by 1,

[0029] If the value of T1 is less than n1, then the B-axis stops rotating within this control cycle and A1 is not updated;

[0030] If the value of T1 is greater than n1, then it is determined that there is a fault in the B-axis rotation angle measurement signal, and at the same time the second counter T2 is cleared.

[0031] Furthermore, the fault judgment and processing module continuously judges the difference between a1 and b1 within the control cycle. When the absolute value of the difference is continuously less than the fault threshold for n2 times, then the fault of the B-axis rotation angle measurement signal is eliminated. Specifically, it includes:

[0032] If it is detected that the absolute value of the difference is greater than the fault threshold, then the first counter T1 is incremented by 1; if it is detected that the absolute value of the difference is less than the fault threshold, then the second counter T2 is incremented by 1, and the first counter T1 is cleared. If it is detected that the absolute value of the difference is greater than the fault threshold, then the second counter T2 is cleared;

[0033] When the second counter T2 is greater than n2, then the fault of the B-axis rotation angle measurement signal is eliminated.

[0034] Furthermore, the fault threshold is equal to 5 degrees.

[0035] Furthermore, n1 = 20 and n2 = 50.

[0036] The advantages of the present invention compared with the prior art are as follows:

[0037] (1) The method of the present invention combines the fault characteristics to establish an on-orbit autonomous diagnosis and control strategy, which can quickly solve the short-term fault problem of the B-axis rotation angle measurement signal;

[0038] (2) After the B-axis rotation angle measurement signal is restored, the present invention autonomously introduces and uses it on the satellite, avoiding the cumulative error introduced by the step pulse rotation angle during long-term use;

[0039] (3) The method and system of the present invention can be popularized and used for spacecraft using a dual-axis solar panel drive mechanism. Description of the Drawings

[0040] Figure 1 Schematic diagram of the dual-axis solar panel drive mechanism of the present invention;

[0041] Figure 2 Block diagram of the B-axis drive mechanism of the present invention;

[0042] Figure 3 Fault-tolerant control flowchart of the B-axis of the present invention. Specific embodiments

[0043] To more clearly illustrate the present invention, the present invention will be further described below in conjunction with actual application examples and drawings. The content described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0044] The present invention proposes a method and system for fault-tolerant control of the ground fault of the angle measurement signal of the dual-axis solar panel drive mechanism. As Figure 1 shown in the dual-axis solar panel drive mechanism, the axis closer to the spacecraft body is the proximal axis (hereinafter referred to as the A-axis), and the axis far from the spacecraft is the distal axis (hereinafter referred to as the B-axis). Taking the center of mass of the spacecraft as the origin, an XYZ coordinate system is established. When the A-axis and the B-axis rotate to the angle of 0 position, the output axes of the A-axis and the B-axis are respectively consistent with the positive directions of the Y-axis and the X-axis of the spacecraft body. The A-axis drives the solar panel to rotate 360 degrees around the Y-axis of the spacecraft body, and the B-axis drives the solar panel to swing within a limited position around the X-axis of the spacecraft body.

[0045] As Figure 2 shown, the B-axis drive mechanism consists of a drive controller, a stepping motor, a drive shaft, and an angle measurement sensor. The rotation angle of the B-axis is measured by the angle measurement sensor, and its measured value is transmitted to the drive controller through the slip ring of the A-axis, serving as the input for the drive controller to calculate the control quantity of the B-axis. The drive controller calculates the control quantity of the B-axis in this cycle according to the angle measured by the B-axis measurement sensor and the azimuth of the sun, and at the same time converts the control quantity of the B-axis into drive pulses corresponding to the number of steps of the stepping motor and acts on the stepping motor, and the stepping motor rotates to drive the B-axis to rotate.

[0046] The fault-tolerant control method for the ground fault of the angle measurement signal of the distal axis of the dual-axis solar panel drive mechanism of the present invention includes:

[0047] S1: For a spacecraft with a dual-axis solar panel, the axis closer to the spacecraft body is taken as the A-axis, and the axis far from the spacecraft is taken as the B-axis; the measured value of the rotation angle of the B-axis collected in each control cycle is denoted as a1, and the number of driving steps nb of the B-axis motor in this control cycle is recorded; the rotation angle of the B-axis corresponding to the number of driving steps nb of the B-axis is denoted as b1.

[0048] In the case of multiple control cycles, the rotation angle of the B-axis in the previous control cycle can be added to the driving angle b1 of the B-axis corresponding to the number of steps nb of the B-axis motor drive in this control cycle as the rotation angle of the B-axis; for the sake of simplicity, the following describes the process of the control method in the case of a single control cycle.

[0049] S2: The initial value of b1 is initialized with the value of a1 read for the first time after power-on. After that, in each control cycle, the difference is obtained by subtracting the value of a1 collected in this control cycle from the value of b1 calculated in this control cycle. If the absolute value of the difference is less than the fault threshold, the spacecraft solar panel drive mechanism is operating normally; at this time, the measured value of the rotation angle of the B-axis in this control cycle is used as the historical value of the rotation angle of the B-axis and recorded as A1.

[0050] In each control cycle, the difference between a1 and b1 is continuously judged. If the absolute value of the difference is greater than the fault threshold, the B-axis stops rotating in this control cycle and A1 is not updated.

[0051] If the difference is greater than the fault threshold for n1 consecutive times, it is determined that the measurement signal of the B-axis rotation angle fails.

[0052] S3: When the measurement signal of the B-axis rotation angle fails, b1 is re-assigned once with the historical value A1 of the B-axis rotation angle, and then b1 is used as the input signal for B-axis rotation control; A1 is the historical value finally saved before the B-axis angle measurement signal fails, and at this time it can represent the true rotation angle of the B-axis. After switching to control with b1, b1 is updated once with A1 first, so that the calculated angle of the b-axis will be more accurate.

[0053] S4: In each control cycle, the difference between a1 and b1 is continuously judged. When the absolute value of the difference is less than the fault threshold for n2 consecutive times, the fault of the B-axis rotation angle measurement signal is eliminated.

[0054] S5: If it is judged that the fault of the B-axis rotation angle measurement signal is eliminated, the current measured value a1 of the B-axis rotation angle is used as the input signal for B-axis rotation control at this time.

[0055] The specific implementation method is as Figure 3 shown:

[0056] S0: Software initialization, collect the measurement signal a1 of the B-axis rotation angle and assign it as the initial value of b1, and at the same time assign initial values to the counters T1, T2 and comparison thresholds n1, n2, C1 used later.

[0057] S1: By default, the measurement signal a1 of the B-axis rotation angle is used as the input for B-axis control quantity calculation.

[0058] S11: In each control cycle, collect a1 and the number of steps nb for the B-axis motor drive. b1 is the rotation angle of the B-axis calculated in the previous control cycle plus the drive angle of the B-axis corresponding to the number of steps nb of the motor in this cycle. The rotation angle corresponding to each step of the motor drive is determined.

[0059] S12: Determine the selection of the threshold value C1 for the angle measurement signal fault of the B-axis rotation angle. The selection of the threshold value is generally determined by the equivalent of the angle measurement signal of the B-axis rotation angle. Generally, it is taken as greater than 5 times the equivalent of the angle measurement signal. Here, 5 degrees is selected.

[0060] S13: The value of n1. The value of n1 should be able to accurately judge the fault and will not affect the normal control of the B-axis. Here, 20 is taken. Since the control of the B-axis depends on the change in the angle between the solar vector and the orbital plane, taking the critical orbit with an inclination of 63.4 degrees as an example, if the control cycle is 1 s, the control amount of the B-axis in one day is 3 degrees, and the control amount of the B-axis corresponding to 20 times of non-control is 0.0007 degrees, which has basically negligible influence on the sailboard tracking the sun; that is, if the B-axis is normal, it should drive the solar sailboard to track the solar vector. 20 times of non-control is equivalent to the angle between the normal of the sailboard and the solar vector differing by 0.0007 degrees, which can be considered to have basically no influence on the energy.

[0061] S14: The value of n2 is generally greater than n1 to ensure that the fault range is determined for the angle measurement signal fault of the B-axis rotation angle. Here, n2 is taken as 50.

[0062] S15: Calculate the difference between a1 and b1. When the absolute value of the angle difference is less than 5 degrees, use a1 as the input for calculating the B-axis control amount, and at the same time update the historical value A1 of the B-axis rotation angle measurement signal with a1 in this cycle.

[0063] S2: The T1 counter is used to judge whether the B-axis angle measurement signal is faulty. If its continuous count is greater than n1, it is considered that the B-axis angle measurement signal is faulty. The T2 counter is used to judge whether the B-axis angle measurement signal returns to normal. If its continuous count is greater than n2, it is considered that the B-axis angle measurement signal fault disappears and returns to normal. For the reliability of the judgment, both of these counters are required to be continuous and need to be used in cooperation with each other.

[0064] If the angle difference is greater than 5 degrees, the counter T1 is incremented by 1. If T1 is less than 20 times, the B-axis stops rotating and A1 is not updated. If T1 is greater than 20 times, assign an initial value to b1 with A1, and then use b1 as the input for calculating the B-axis control amount, and at the same time clear the counter T2 to 0. The reason why T1 is required to have a continuous count greater than n1 is that if the B-axis angle measurement signal has an occasional jump, it can be considered as an outlier. The B-axis is stopped from being controlled for 1 control cycle, and in the next cycle, it is still controlled by a1, and it is not easily switched to b1.

[0065] S3: T2 also needs to count continuously to confirm that the B-axis angle measurement signal has indeed disappeared from the fault. The difference between a1 and b1 is judged in each control cycle. When the difference is less than 5 degrees, T2 is incremented by 1 and T1 is cleared to 0. Once the difference is greater than 5 degrees, T2 is cleared to 0. When T2 is less than 50, b1 is used as the input for calculating the B-axis control amount. When T2 is greater than 50, it is considered that the fault of the B-axis rotation angle measurement signal has been eliminated.

[0066] S4: The controller software autonomously switches to using a1 as the input for B-axis control.

[0067] On the other hand, the present invention also proposes a fault-tolerant control system for the ground fault of the remote-axis angle measurement signal of a dual-axis solar panel drive mechanism, including: an initialization module, a fault judgment module, and a rotation angle update module.

[0068] The initialization module sets the initial value of b1. The initial value of b1 is equal to the value of a1 read for the first time after power-on. After that, in each control cycle, the difference between the value of a1 collected in this control cycle and the value of b1 calculated in this control cycle is obtained. Among them, for the spacecraft with a dual-axis solar panel, the axis closer to the spacecraft body is taken as the A-axis, and the axis far from the spacecraft is taken as the B-axis; the measured value of the B-axis rotation angle collected in each control cycle is denoted as a1, and the number of steps nb of the B-axis motor drive in this control cycle is recorded; the B-axis rotation angle corresponding to the number of steps of the B-axis drive is denoted as b1.

[0069] The fault judgment module judges the working state of the spacecraft solar panel drive mechanism according to the difference. If the absolute value of the difference is less than the fault threshold, the spacecraft solar panel drive mechanism is working normally; at this time, the measured value of the B-axis rotation angle in this control cycle is used as the historical value of the B-axis rotation angle and denoted as A1.

[0070] During the control cycle, the difference between a1 and b1 is continuously judged. If the absolute value of the difference is greater than the fault threshold, the B-axis stops rotating in this control cycle and A1 is not updated.

[0071] If the difference is greater than the fault threshold for n1 consecutive times, it is determined that the B-axis rotation angle measurement signal has a fault.

[0072] When the absolute value of the difference is less than the fault threshold for n2 consecutive times, the fault of the B-axis rotation angle measurement signal is eliminated.

[0073] When the B-axis rotation angle measurement signal has a fault, the rotation angle update module reassigns the value of b1 with the historical value A1 of the B-axis rotation angle, and at the same time uses b1 as the input signal for B-axis rotation control.

[0074] When the fault of the B-axis rotation angle measurement signal is eliminated, the current measured value a1 of the B-axis rotation angle is used as the input signal for B-axis rotation control.

[0075] The fault judgment module judges that: if the absolute value of the difference is greater than the fault threshold, the B-axis stops rotating in the current control cycle and A1 is not updated; if the difference is greater than the fault threshold for n1 consecutive times, it is determined that there is a fault in the B-axis rotation angle measurement signal; specifically including:

[0076] Set a first counter T1, and the first counter T1 records the number of times the difference is continuously greater than the fault threshold; set a second counter T2, and the second counter T2 records the number of times the difference is continuously less than the fault threshold.

[0077] If it is detected that the absolute value of the difference is greater than the fault threshold, the first counter T1 is incremented by 1.

[0078] If it is detected that the absolute value of the difference is less than the fault threshold, the second counter T2 is incremented by 1.

[0079] If the value of T1 is less than n1, the B-axis stops rotating in the current control cycle and A1 is not updated.

[0080] If the value of T1 is greater than n1, it is determined that there is a fault in the B-axis rotation angle measurement signal, and at the same time the second counter T2 is cleared.

[0081] The fault judgment module judges that when the absolute value of the difference is less than the fault threshold for n2 consecutive times, the fault of the B-axis rotation angle measurement signal is eliminated, specifically including:

[0082] If it is detected that the absolute value of the difference is greater than the fault threshold, the first counter T1 is incremented by 1; if it is detected that the absolute value of the difference is less than the fault threshold, the second counter T2 is incremented by 1, and the first counter T1 is cleared, and if it is detected that the absolute value of the difference is greater than the fault threshold, the second counter T2 is cleared.

[0083] When the second counter T2 is greater than n2, the fault of the B-axis rotation angle measurement signal is eliminated.

[0084] The content not described in detail in the specification of the present invention belongs to the common general knowledge of those skilled in the art.

Claims

1. A fault-tolerant control method for the ground fault of the angle measurement signal of a biaxial windsurfing drive mechanism, characterized in that, Including: For a spacecraft with a two-axis solar sailboard, the axis closer to the spacecraft body is defined as axis A, and the axis farther from the spacecraft is defined as axis B; the measured value of the rotation angle of axis B collected in each control cycle is denoted as a1, and the number of driving steps of the axis B motor in this control cycle is recorded, and the rotation angle of axis B corresponding to the number of driving steps of the axis B motor is denoted as b1; First, set the initial value of b1 to be equal to the value of a1 read for the first time after power-on. In each control cycle, subtract the value of a1 collected in this control cycle from the value of b1 in this control cycle to obtain a difference value; Judge the working state of the spacecraft solar sailboard driving mechanism according to the difference value. If the absolute value of the difference value is less than the fault threshold, it is determined that the spacecraft solar sailboard driving mechanism is working normally; If the difference value is greater than the fault threshold continuously for n1 times, it is determined that a fault occurs in the measurement signal of the rotation angle of axis B. At this time, reassign b1 with the historical value A1 of the rotation angle of axis B, and at the same time use b1 as the input signal for the rotation control of axis B; the last measured value of the rotation angle of axis B in this control cycle is used as the historical value A1 of the rotation angle of axis B; After it is determined that a fault occurs in the measurement signal of the rotation angle of axis B, continuously judge the difference between a1 and b1 in each control cycle. When the absolute value of the difference value is less than the fault threshold continuously for n2 times, it is determined that the fault of the measurement signal of the rotation angle of axis B is eliminated. At this time, use the current measured value a1 of the rotation angle of axis B as the input signal for the rotation control of axis B.

2. The method according to claim 1, characterized in that, If the difference value is greater than the fault threshold continuously for n1 times, it is determined that a fault occurs in the measurement signal of the rotation angle of axis B, specifically including: Set a first counter T1, and the first counter T1 records the number of times the difference value is continuously greater than the fault threshold; set a second counter T2, and the second counter T2 records the number of times the difference value is continuously less than the fault threshold; If it is detected that the absolute value of the difference value is greater than the fault threshold, the first counter T1 is incremented by 1, If it is detected that the absolute value of the difference value is less than the fault threshold, the second counter T2 is incremented by 1, If the value of T1 is less than n1, axis B stops rotating in this control cycle and A1 is not updated; If the value of T1 is greater than n1, it is determined that a fault occurs in the measurement signal of the rotation angle of axis B, and at the same time the second counter T2 is cleared.

3. The method according to claim 2, characterized in that, The continuous judgment of the difference between a1 and b1 in the control cycle. When the absolute value of the difference value is less than the fault threshold continuously for n2 times, the fault of the measurement signal of the rotation angle of axis B is eliminated, specifically including: If it is detected that the absolute value of the difference value is greater than the fault threshold, the first counter T1 is incremented by 1; if it is detected that the absolute value of the difference value is less than the fault threshold, the second counter T2 is incremented by 1, and the first counter T1 is cleared. If it is detected that the absolute value of the difference value is greater than the fault threshold, the second counter T2 is cleared; When the value of the second counter T2 is greater than n2, it is determined that the fault of the measurement signal of the rotation angle of axis B is eliminated.

4. The method according to claim 1, wherein The fault threshold is equal to 5 degrees.

5. The method according to claim 1, wherein The n1 = 20 and n2 = 50.

6. A biaxial windsurfing board drive mechanism angle measurement signal grounding fault tolerance control system, characterized in that, It includes: An initialization module and a fault judgment and processing module, where, Initialization module: Set the initial value of b1, where the initial value of b1 is equal to the value of a1 read for the first time after power-on. In each control cycle, calculate the difference between the value of a1 collected in this control cycle and the value of b1 in this control cycle; for a spacecraft with a two-axis solar panel, the axis closer to the spacecraft body is defined as axis A, and the axis farther from the spacecraft is defined as axis B; record the measured value of the rotation angle of axis B collected in each control cycle as a1, record the number of motor drive steps of axis B in this control cycle, and define the rotation angle of axis B corresponding to the number of drive steps of axis B as b1. The last measured value of the rotation angle of axis B in this control cycle is used as the historical value A1 of the rotation angle of axis B. Fault judgment and processing module: Judge the working state of the spacecraft solar panel drive mechanism according to the difference. If the absolute value of the difference is less than the fault threshold, it is determined that the spacecraft solar panel drive mechanism is working normally. If the difference is greater than the fault threshold for n1 consecutive times, it is determined that a fault has occurred in the measured signal of the rotation angle of axis B. At this time, reassign b1 with the historical value A1 of the rotation angle of axis B, and at the same time use b1 as the input signal for the rotation control of axis B. After it is determined that a fault has occurred in the measured signal of the rotation angle of axis B, continuously judge the difference between a1 and b1 within the control cycle. When the absolute value of the difference is less than the fault threshold for n2 consecutive times, it is determined that the fault of the measured signal of the rotation angle of axis B has been eliminated. At this time, use the current measured value a1 of the rotation angle of axis B as the input signal for the rotation control of axis B.

7. The system according to claim 6, wherein If the difference is greater than the fault threshold for n1 consecutive times, the fault judgment and processing module determines that a fault has occurred in the measured signal of the rotation angle of axis B, specifically including: Set the first counter T1, where the first counter T1 records the number of times the difference is continuously greater than the fault threshold; set the second counter T2, where the second counter T2 records the number of times the difference is continuously less than the fault threshold. If it is detected that the absolute value of the difference is greater than the fault threshold, the first counter T1 is incremented by 1. If it is detected that the absolute value of the difference is less than the fault threshold, the second counter T2 is incremented by 1. If the value of T1 is less than n1, axis B stops rotating in this control cycle and A1 is not updated. If the value of T1 is greater than n1, it is determined that a fault has occurred in the measured signal of the rotation angle of axis B, and at the same time the second counter T2 is cleared.

8. The system according to claim 7, characterized in that, The fault judgment and processing module continuously judges the difference between a1 and b1 within the control cycle. When the absolute value of the difference is less than the fault threshold for n2 consecutive times, the fault of the measured signal of the rotation angle of axis B is eliminated, specifically including: If it is detected that the absolute value of the difference is greater than the fault threshold, the first counter T1 is incremented by 1; if it is detected that the absolute value of the difference is less than the fault threshold, the second counter T2 is incremented by 1, and the first counter T1 is cleared. If it is detected that the absolute value of the difference is greater than the fault threshold, the second counter T2 is cleared. When the value of the second counter T2 is greater than n2, the fault of the measured signal of the rotation angle of axis B is eliminated.

9. The system according to claim 6, characterized in that, The fault threshold is equal to 5 degrees.

10. The system according to claim 6, wherein The n1 = 20 and n2 = 50.

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