Fault diagnosis and online calibration device and method for spacecraft executing mechanism based on double sensors

Abstract

The invention discloses a spacecraft executing mechanism fault diagnosis and online calibration device and method based on double sensors, and belongs to the technical field of aircraft control and ground simulation. In order to carry out detection and off-line compensation on errors, the device comprises an absolute grating encoder, an actuating mechanism expansion shaft, an inductosyn, a control moment gyroscope, a photoelectric reading head and a signal amplification circuit, the absolute grating encoder, the inductosyn and the control moment gyroscope are coaxially installed through the executing mechanism expansion shaft, one end of the executing mechanism expansion shaft is connected with the absolute grating encoder, the other end of the executing mechanism expansion shaft is connected with the inductosyn, and the inductosyn is connected with the control moment gyroscope. The absolute grating encoder is connected with a first processing circuit box through a photoelectric reading head wire, and the first processing circuit box is connected with an upper computer. The inductosyn is connected with the signal amplification circuit and the excitation power supply through wires, the signal amplification circuit is connected with the second processing circuit box through a wire, and the second processing circuit box is connected with the upper computer.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft control and ground simulation, and in particular relates to a dual-sensor based device and method for fault diagnosis and online calibration of a spacecraft actuator. Background Art

[0002] The spacecraft attitude control actuator is a device that generates control torque on the spacecraft and is an important part of the spacecraft attitude control system. It is controlled by the controller and generates torque acting on the spacecraft. The control torque generated by the attitude control actuator is used for: attitude stabilization, attitude maneuvering, maintaining and establishing the attitude required for orbit control, spin-up, de-spinning, speed control, nutation and precession control of spin-stabilized satellites, and attitude capture of spacecraft, which require precise control.

[0003] The invention patent with the patent number CN201810622584.4 and the invention name "A method for analyzing and compensating the angular measurement error of an inductive synchronizer" uses a high-precision single-axis test turntable as the angular measurement reference, and uses the least squares identification method to complete the harmonic analysis of the angular measurement error of the inductive synchronizer. According to the analysis results, the corresponding hardware adjustments are carried out in a targeted manner, and then the error data is collected again as the compensation sampling points, and the angular measurement error software is compensated using the linear interpolation method. It solves the problems of incomplete analysis, unsatisfactory compensation effect, limited number of sampling points, low efficiency and difficulty in model establishment in the existing inductive synchronizer analysis and compensation methods. However, the detection implementation process is relatively complicated. Summary of the invention

[0004] The problem to be solved by the present invention is to detect and compensate for errors offline, and a dual-sensor-based device and method for fault diagnosis and online calibration of a spacecraft actuator are proposed.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A dual-sensor-based spacecraft actuator fault diagnosis and online calibration device, comprising an absolute grating encoder, an actuator extension shaft, an inductive synchronizer, a control torque gyro, a photoelectric reading head, a signal amplification circuit, an excitation power supply, a first processing circuit box, a second processing circuit box, and a host computer;

[0007] The absolute grating encoder, the inductive synchronizer and the control torque gyro are coaxially installed through the actuator extension shaft, one end of the actuator extension shaft is connected to the absolute grating encoder, the other end of the actuator extension shaft is connected to the inductive synchronizer, and the inductive synchronizer is connected to the control torque gyro;

[0008] The absolute grating encoder is connected to a first processing circuit box via a photoelectric reading head wire, and the first processing circuit box is connected to a host computer;

[0009] The induction synchronizer is connected to the signal amplification circuit and the excitation power supply through wires, the signal amplification circuit is connected to the second processing circuit box through wires, and the second processing circuit box is connected to the host computer.

[0010] Furthermore, the photoelectric signal of the absolute grating encoder is read by a photoelectric reading head in two ways, namely, coarse and fine, and then connected to the first processing circuit box to be converted into an angle value feedback, which is then fed back to the host computer.

[0011] Furthermore, the induction synchronizer is single-phase excited by an excitation power supply, and the obtained two-phase output signal is first connected to a signal amplification circuit, and after the amplified signal is connected to a second processing circuit box, converted into an angle value feedback, and fed back to the host computer.

[0012] A method for fault diagnosis and online calibration of a spacecraft actuator based on dual sensors is implemented based on a device for fault diagnosis and online calibration of a spacecraft actuator based on dual sensors, and includes the following steps:

[0013] S1. When the actuator is located on the ground, the parameters to be identified of the induction synchronizer are constructed, the angle measurement error of the induction synchronizer is calibrated once, the angle measurement feedback of the absolute grating encoder is used as the angle measurement reference, the parameters to be identified of the angle measurement error of the induction synchronizer are identified offline, and then the identification results are compensated using the offline compensation method to complete the offline error calibration of the actuator;

[0014] S2. Based on the on-orbit operation of the actuator, the output angle measurement signal characteristics of the induction synchronizer when the actuator fails to operate on-orbit are constructed, and the output angle measurement signal characteristics of the absolute grating encoder when the actuator fails to operate on-orbit are constructed for fault judgment, and then a fault diagnosis method based on open-loop operation is constructed based on the working principle of the control moment gyro to diagnose major faults. If a major fault is diagnosed, step S3 is executed, and if no major fault is diagnosed, step S4 is executed;

[0015] S3. For a major fault diagnosed, feedback of the major fault information obtained in step S3 is sent to the host computer;

[0016] S4. For those diagnosed as having no major faults, use the induction synchronizer to perform online detection and compensation of the angular measurement error to complete the online error calibration of the actuator.

[0017] Furthermore, the specific implementation method of step S1 includes the following steps:

[0018] S1.1. Based on the fact that the main error of the induction synchronizer is the secondary component and DC component of the current electrical angle, the actual angle error angle Δα of the induction synchronizer is established D , the expression is:

[0019] Δα D =Δα D0 +Δα D1 +Δα D2 +ε

[0020] Among them, Δα D0 The DC component angle of the induction synchronizer’s angular error, Δα D1 Indicates the error angle caused by the inaccurate scale of the induction synchronizer itself and the non-orthogonality of the two phases, Δα D2 It represents the error angle caused by the unequal amplitude of the two phases of the exciting power supply and the non-orthogonal phase, and ε represents the measurement noise;

[0021] Establishing Δα D1 The expression is:

[0022]

[0023] Among them, Δα represents the adjacent orthogonal error angle of the two-phase windings, Δε represents the adjacent amplitude error angle of the two-phase windings, and α D Indicates the current electrical angle of the induction synchronizer;

[0024] Establishing Δα D2 The expression is:

[0025]

[0026] in, It represents the phase error between the two phases of the exciting power supply, and ΔU represents the amplitude error between the two phases of the exciting power supply;

[0027] Δα D1 and Δα D2 The actual angle measurement error Δα of the induction synchronizer D The expression of is:

[0028]

[0029] Known Δα D , α D All are detectable quantities, set Δα D0 , Δε-ΔU is the parameter to be identified of the induction synchronizer;

[0030] S1.2. Using the one-time least square method, based on the parameters to be identified of the induction synchronizer obtained in step S1.4, the angle measurement error of the induction synchronizer is calibrated once, and the expression is:

[0031]

[0032] in, represents the matrix of parameters to be identified, Φ represents the matrix composed of operation results, and Y represents the matrix composed of measurement values;

[0033] The expression is:

[0034]

[0035] The expression of Φ is:

[0036]

[0037] Among them, α D (N) represents the electrical angle position of the Nth induction synchronizer;

[0038] The expression of Y is:

[0039]

[0040] Among them, Δα D (N) represents the angle measurement error value of the Nth electrical angle of the induction synchronizer;

[0041] S1.3. Take the angle measurement feedback of the absolute grating encoder as the angle measurement reference, evenly select 23 test points within the full 360-degree range, record the feedback angle measurement values ​​of the induction synchronizer and the absolute grating encoder at the corresponding test points, and make a difference between the feedback angle measurement values ​​of the induction synchronizer and the absolute grating encoder to obtain Δα at each location. D The value of; bring in the matrix composed of the measured values, and use the one-time least square method to perform offline identification on the parameters to be identified of the induction synchronizer angular measurement error, and obtain the identification result, which is expressed as:

[0042]

[0043] Among them, A, B, and C represent the identification results corresponding to the amplitudes of the error components to be compensated;

[0044] S1.4. Use the offline compensation method to compensate the identification result obtained in step S1.3, denoted by α D is the current electrical angle position of the induction synchronizer, then the calculation formula for the actual angle measurement angle α′ of the induction synchronizer is:

[0045]

[0046] Furthermore, the specific implementation method of step S2 includes the following steps:

[0047] S2.1. Construct the output angle measurement signal characteristics of the induction synchronizer when the actuator fails during on-orbit operation;

[0048] S2.1.1. Considering that the induction synchronizer uses a continuous winding and a sinusoidal signal to excite, and the segmented winding outputs the potential, and works in the amplitude detection mode, the excitation circuit generates an excitation signal E that changes sinusoidally with time, which is expressed as:

[0049] E=E 0 sinωt

[0050] Among them, E 0 represents the amplitude of the excitation signal, ω represents the angular frequency of the excitation signal, and t represents time;

[0051] The excitation signal is directly applied to the continuous winding end of the induction synchronizer. The A and B phase segmented windings of the induction synchronizer are orthogonal in space, so that the A phase potential E of the induction synchronizer is induced on the two phase windings respectively. A 、B-phase potential E of the induction synchronizer B , the expression is:

[0052]

[0053] Among them, k A , k B It represents the voltage transfer ratio between the primary and secondary windings of the induction synchronizer;

[0054] S2.1.2. Set the A-phase potential E of the induction synchronizer A 、B-phase potential E of the induction synchronizer B After passing through the signal amplification circuit, it is input into the second processing circuit box, and the obtained A phase signal is U A , B phase signal is U B , the expression is:

[0055]

[0056] Among them, G A , G B Indicates the amplification factor of the signal amplifier circuit;

[0057] When the induction synchronizer is working normally, the amplification factor of the signal amplifier circuit ensures that the signal U input to the second processing circuit box is A , U B The maximum amplitude of is consistent, denoted by E m , the expression is:

[0058]

[0059] S2.1.3. Based on the induction synchronizer operating in the amplitude detection mode, the output of the signal amplification circuit in the second processing circuit box is connected to the function transformer to obtain two new potential signals U of phase A and phase B. A ',U B', the expression is:

[0060]

[0061] in, is the adjustable and measurable variable in the function transformer. The two new potential signals are superimposed by the adder to obtain the total output potential U, which is expressed as:

[0062]

[0063] When the induction synchronizer rotates to any certain position α D , by adjusting the variable Until the output potential U points to zero, record the current variable The value of the current electrical angle α D The measured value is obtained, and then the mechanical angle α of the current position is obtained according to the relationship between the mechanical angle and the electrical angle of the induction synchronizer. The expression is:

[0064] α D =Pα

[0065] Where P represents the number of pole pairs of the induction synchronizer, which completes the measurement of the current angle;

[0066] S2.1.4. Analyze the information characteristics of the induction synchronizer measurement results when the excitation power supply fails during on-orbit operation:

[0067] The excitation circuit open circuit fault means that there is no excitation signal input at all, then the total output potential U is 0, and the total output potential measured is a series of noise, α D The actual measured value is a series of noise and is related to the measured value at the previous moment, which depends on the dynamic tracking speed of the angle measurement;

[0068] S2.1.5. Analyze the information characteristics of the induction synchronizer measurement results when the signal amplifier circuit is open-circuited during on-orbit operation:

[0069] If one phase signal amplifier circuit of the induction synchronizer is open, the expression of the total output potential U is:

[0070]

[0071] According to the expression, no matter where the induction synchronizer is, U points to zero. The expression is:

[0072]

[0073] The value of k depends on the position of the induction synchronizer at the time of the fault, and the value of α from the time when the signal amplifier circuit open circuit fault occurs is obtained. DThe actual measured value is a constant value, which is the information characteristic of the measurement result of the induction synchronizer when the signal amplification circuit is open;

[0074] S2.2. Construct the output angle measurement signal characteristics of the absolute grating encoder when the actuator fails during on-track operation;

[0075] S2.2.1. The absolute grating encoder is arranged in a matrix, and operates in a combination of 8 photoelectric reading heads, a 12-bit coarse angle measurement channel with 2-circle code channels, and a fine angle measurement channel with a 16-bit subdivision angle measurement function;

[0076] S2.2.2. The rough angle measurement channel is encoded with Gray code. Eight photoelectric reading heads are evenly placed on the first circle of code tracks to convert the optical signal into a pulse electrical signal. The relationship between the eight optical signals a of the first circle and the first four bits of Gray code A is:

[0077]

[0078] in, It means that the optical signal a is negated;

[0079] On the second circle code channel, eight-quadrant matrix encoding is used, and eight photoelectric reading heads are evenly placed on a 360° circumference. The Gray code is obtained by the relationship between the eight optical signals of the second circle and the last eight bits of Gray code, and then decoded by the first processing circuit box to obtain the corresponding coarse channel angle measurement value;

[0080] S2.2.3. The sine signal and cosine signal output by the photoelectric reading head of the fine angle measurement channel are converted into 16-bit A / D, and the fine channel angle measurement value within the coarse channel angle measurement resolution is calculated after being converted into digital signals. The coarse channel angle measurement value and the fine channel angle measurement value obtained in step S2.2.2 are combined to obtain the final angle measurement result output by the absolute grating encoder;

[0081] S2.2.2. Set the absolute grating encoder to be a photoelectric reading head failure when the actuator is running on track. When at least one photoelectric reading head fails to work properly, the feedback angle measurement value shows a non-discontinuous feature near the position where the error occurs, and obtain the output angle measurement signal characteristics of the absolute grating encoder when the actuator fails to run on track;

[0082] S2.3. Construct the output angle measurement signal characteristic Δα′ when the actuator fails during on-orbit operation, and the expression is:

[0083] Δα′=α 1 -α 2

[0084] Among them, α 1 Indicates the angle of the induction synchronizer at a certain moment, α 2Indicates the angle of the absolute grating encoder at a certain moment;

[0085] When Δα′ is no longer within the set threshold range, it is preliminarily judged that the actuator has a fault in orbit operation; then take n 1 sampling points, when it is determined that there are n 2 If the sampling points satisfy the following relationship, it is judged that a fault in the angle measuring device is detected, and the expression is:

[0086]

[0087] Among them, p 0 The confidence level is manually set;

[0088] S2.4. Construct a fault diagnosis method based on open-loop operation based on the working principle of the control moment gyro;

[0089] S2.4.1. Using the method of step S2.3, determine whether the inductive synchronizer and the absolute grating encoder have failed according to the true angle value and the angle measurement result. When it is determined that the inductive synchronizer has failed, proceed to step S2.4.2. When it is determined that the absolute grating encoder has failed, proceed to step S2.4.3.

[0090] S2.4.2. First, determine whether the current fault is caused by an open circuit in the excitation circuit based on whether the angle measurement signal after the fault is periodic; use the method in step S2.3 to verify the periodicity of the angle measurement result. When the induction synchronizer rotates to the same position twice and the angle measurement result exceeds the threshold, the fault is caused by an open circuit in the excitation circuit;

[0091] When the induction synchronizer rotates to the same position twice and the angle measurement result is periodic, check whether the fault is caused by the open circuit of the signal amplifier circuit. The judgment standard is that the angle measurement result is a constant value. Record the most recent N 3 The angle measurement result at the sampling point α 5 , and calculate the mean of the angle measurements Find this N 3 The number of data points that do not satisfy the following formula among the sampling points is N 4 , the expression is:

[0092]

[0093] Among them, p 3 is a confidence level set artificially. If N 3 、N 4 、p 3 If the following relationship is satisfied, it is considered that the angle measurement result of the induction synchronizer of this fault is a constant value. The cause of the fault is diagnosed as an open circuit in the signal amplifier circuit. The expression is:

[0094]

[0095] S2.4.3. The fault caused by the absolute grating encoder is a fault in which the photoelectric reading head cannot receive the light-sensitive signal. The judgment basis is that the absolute grating encoder fault detection confidence is not less than 0.5 and the angle measurement result is periodic. If the above conditions are met, the absolute grating encoder is diagnosed as having a fault.

[0096] Furthermore, the specific implementation method of step S4 includes the following steps:

[0097] S4.1. Establish the actual online angle measurement error angle Δα of the induction synchronizer D ′, the expression is:

[0098] Δα D ′=Δα D0 +Δα D1 +Δα D2 +Δα Dc +ε

[0099] Among them, Δα Dc is the online compensation angle, and the expression is:

[0100]

[0101] Among them, α A , α B , α C They respectively represent the corresponding compensation coefficients of the online errors to be identified;

[0102] Substituting in:

[0103]

[0104] Based on the above formula, we get Δα D , α D All are detectable quantities, set Δα D0 +α A , Δε-ΔU+α C is the online parameter to be identified;

[0105] S4.2. For the α obtained in step S4.1 A , α B , α C Real-time adjustment based on the results of online identification; the compensation coefficient is adjusted once every 1 second, and the compensation coefficient after the kth compensation is α A (k), α B (k), α C (k), the compensation coefficient after the k+1th compensation is αA (k+1),α B (k+1),α C (k+1), then the k-th online parameter to be identified is Then the expression is:

[0106]

[0107] S4.3. Construct an online identification method using recursive memory-eliminating least squares method, and obtain The online identification expression of is:

[0108]

[0109] Among them, λ represents the forgetting factor of the gradual memory method, K represents the gain matrix, P represents the covariance matrix, and y represents the measurement error matrix. represents the operation matrix;

[0110]

[0111] Beneficial effects of the present invention:

[0112] The dual-sensor-based spacecraft actuator fault diagnosis and online calibration device described in the present invention is for a certain fixed axis, and an absolute grating encoder and an inductive synchronizer are installed as angle measuring sensors at the same time to form a dual-sensor actuator. In addition to being able to perform online error identification and compensation of the inductive synchronizer and timely diagnosis of sensor failures, the actuator can also ensure the normal operation of the spacecraft when one of the sensors fails, thereby improving the operating life and reliability of the on-orbit spacecraft.

[0113] The dual-sensor based spacecraft actuator fault diagnosis and online calibration method described in the present invention can detect and compensate for the principle angle measurement error of the induction synchronizer angle measurement system itself by using dual sensors on the ground to ensure its angle measurement accuracy.

[0114] The proposed dual-sensor actuator can verify whether the angle measurement system is faulty based on its own two-way angle measurement feedback through real-time algorithm comparison, and can accurately determine the source of the fault when a fault occurs. In view of the time-varying parameters of the induction synchronizer during on-orbit operation, a method using the fading memory least squares method to perform online identification and compensation of its parameters is proposed, which effectively improves the angle measurement accuracy with significant results. The proposed dual-sensor actuator can ensure the normal operation of the spacecraft when one of the sensors fails, and can improve the operating life and reliability of the on-orbit spacecraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0115] Figure 1It is a structural schematic diagram of a dual-sensor-based spacecraft actuator fault diagnosis and online calibration device according to the present invention;

[0116] Figure 2 for;

[0117] Figure 3 This is a diagram of the angle measurement error of the slow time-varying open-loop compensation induction synchronizer of the present invention;

[0118] Figure 4 This is a diagram of the angle measurement error of the slow time-varying recursive and gradually disappearing memory closed-loop compensation induction synchronizer of the present invention;

[0119] Figure 5 This is a diagram of the slow time-varying recursive gradual memory recognition result of the present invention;

[0120] Figure 6 This is a diagram of the angle measurement error of the sudden open-loop compensation induction synchronizer of the present invention;

[0121] Figure 7 This is a diagram of the angle measurement error of the sudden recursive gradual memory closed-loop compensation induction synchronizer of the present invention;

[0122] Figure 8 This is a diagram of the recognition result of the mutation recursive gradual memory extinction of the present invention;

[0123] Fig. 9 The present invention is a flow chart of a method for fault diagnosis and online calibration of a spacecraft actuator based on dual sensors. DETAILED DESCRIPTION

[0124] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the specific embodiments described are only part of the embodiments of the present invention, rather than all of the specific embodiments. The components of the specific embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations, and the present invention can also have other embodiments.

[0125] Therefore, the following detailed description of the specific embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected specific embodiments of the present invention. Based on the specific embodiments of the present invention, all other specific embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0126] In order to further understand the content, features and effects of the present invention, the following specific implementation methods are given as examples, and the attached Figure 1 -Attached Fig. 9The detailed instructions are as follows:

[0127] Embodiment 1:

[0128] A dual-sensor-based spacecraft actuator fault diagnosis and online calibration device, comprising an absolute grating encoder 1, an actuator extension shaft 2, an inductive synchronizer 3, a control torque gyro 4, a photoelectric reading head 5, a signal amplification circuit 6, an excitation power supply 7, a first processing circuit box 8, a second processing circuit box 9, and a host computer 10;

[0129] The absolute grating encoder 1, the inductive synchronizer 3 and the control torque gyro 4 are coaxially installed through the actuator extension shaft 2, one end of the actuator extension shaft 2 is connected to the absolute grating encoder 1, the other end of the actuator extension shaft 2 is connected to the inductive synchronizer 3, and the inductive synchronizer 3 is connected to the control torque gyro 4;

[0130] The absolute grating encoder 1 is connected to the first processing circuit box 8 through the photoelectric reading head 5 wire, and the first processing circuit box 8 is connected to the host computer 10;

[0131] The induction synchronizer 3 is connected to a signal amplifying circuit 6 and an excitation power supply 7 through wires, respectively. The signal amplifying circuit 6 is connected to a second processing circuit box 9 through wires, and the second processing circuit box 9 is connected to a host computer 10 .

[0132] Furthermore, the photoelectric signal of the absolute grating encoder 1 is read by the photoelectric reading head 5 in two ways, namely, coarse and fine, and then connected to the first processing circuit box 8 to be converted into an angle value feedback, and then fed back to the host computer.

[0133] Furthermore, the induction synchronizer 3 is single-phase excited by the excitation power supply 7, and the obtained two-phase output signal is first connected to the signal amplification circuit 6, and after the amplified signal is connected to the second processing circuit box 9, it is converted into an angle value feedback and fed back to the host computer.

[0134] Embodiment 2:

[0135] A method for fault diagnosis and online calibration of a spacecraft actuator based on dual sensors is implemented based on the device for fault diagnosis and online calibration of a spacecraft actuator based on dual sensors described in Example 1, and includes the following steps:

[0136] S1. When the actuator is located on the ground, the parameters to be identified of the induction synchronizer are constructed, the angle measurement error of the induction synchronizer is calibrated once, the angle measurement feedback of the absolute grating encoder is used as the angle measurement reference, the parameters to be identified of the angle measurement error of the induction synchronizer are identified offline, and then the identification results are compensated using the offline compensation method to complete the offline error calibration of the actuator;

[0137] In the dual-sensor fault diagnosis and calibration device, for the control torque gyro, both the induction synchronizer and the absolute grating encoder are used as angle feedback devices. The absolute grating encoder can obtain higher angle measurement accuracy than the induction synchronizer. At the same time, the matrix encoding method of the absolute grating encoder can obtain more encoder lines in the same space, which helps to integrate the angle measurement circuit in a smaller size.

[0138] Compared with the absolute grating encoder, the induction synchronizer has stronger anti-interference ability and works more stably. Based on the above characteristics, the angle measurement feedback of the absolute grating is used as the angle measurement reference on the ground to identify and compensate the relevant parameters of the angle measurement error of the induction synchronizer offline.

[0139] Furthermore, the specific implementation method of step S1 includes the following steps:

[0140] S1.1. Based on the fact that the main error of the induction synchronizer is the secondary component and DC component of the current electrical angle, the actual angle error angle Δα of the induction synchronizer is established D , the expression is:

[0141] Δα D =Δα D0 +Δα D1 +Δα D2 +ε

[0142] Among them, Δα D0 The DC component angle of the induction synchronizer’s angular error, Δα D1 Indicates the error angle caused by the inaccurate scale of the induction synchronizer itself and the non-orthogonality of the two phases, Δα D2 It represents the error angle caused by the unequal amplitude of the two phases of the exciting power supply and the non-orthogonal phase, and ε represents the measurement noise;

[0143] Establishing Δα D1 The expression is:

[0144]

[0145] Among them, Δα represents the adjacent orthogonal error angle of the two-phase windings, Δε represents the adjacent amplitude error angle of the two-phase windings, and α D Indicates the current electrical angle of the induction synchronizer;

[0146] Establishing Δα D2 The expression is:

[0147]

[0148] in, It represents the phase error between the two phases of the exciting power supply, and ΔU represents the amplitude error between the two phases of the exciting power supply;

[0149] Δα D1 and Δα D2 The actual angle measurement error Δα of the induction synchronizer D The expression of is:

[0150]

[0151] Known Δα D , α D All are detectable quantities, set Δα D0 , Δε-ΔU is the parameter to be identified of the induction synchronizer;

[0152] S1.2. Using the one-time least square method, based on the parameters to be identified of the induction synchronizer obtained in step S1.4, the angle measurement error of the induction synchronizer is calibrated once, and the expression is:

[0153]

[0154] in, represents the matrix of parameters to be identified, Φ represents the matrix composed of operation results, and Y represents the matrix composed of measurement values;

[0155] The expression is:

[0156]

[0157] The expression of Φ is:

[0158]

[0159] Among them, α D (N) represents the electrical angle position of the Nth induction synchronizer;

[0160] The expression of Y is:

[0161]

[0162] Among them, Δα D (N) represents the angle measurement error value of the Nth electrical angle of the induction synchronizer;

[0163] S1.3. Take the angle measurement feedback of the absolute grating encoder as the angle measurement reference, evenly select 23 test points within the full 360-degree range, record the feedback angle measurement values ​​of the induction synchronizer and the absolute grating encoder at the corresponding test points, and make a difference between the feedback angle measurement values ​​of the induction synchronizer and the absolute grating encoder to obtain Δα at each location. DThe value of; bring in the matrix composed of the measured values, and use the one-time least square method to perform offline identification on the parameters to be identified of the induction synchronizer angular measurement error, and obtain the identification result, which is expressed as:

[0164]

[0165] Among them, A, B, and C represent the identification results corresponding to the amplitudes of the error components to be compensated;

[0166] S1.4. Use the offline compensation method to compensate the identification result obtained in step S1.3, denoted by α D is the current electrical angle position of the induction synchronizer, then the calculation formula for the actual angle measurement angle α′ of the induction synchronizer is:

[0167]

[0168] S2. Based on the on-orbit operation of the actuator, the output angle measurement signal characteristics of the induction synchronizer when the actuator fails to operate on-orbit are constructed, and the output angle measurement signal characteristics of the absolute grating encoder when the actuator fails to operate on-orbit are constructed for fault judgment, and then a fault diagnosis method based on open-loop operation is constructed based on the working principle of the control moment gyro to diagnose major faults. If a major fault is diagnosed, step S3 is executed, and if no major fault is diagnosed, step S4 is executed;

[0169] When the actuator is running on-orbit, the dual sensor fault diagnosis and on-orbit calibration device can identify the fault state of the current sensor according to the two-way angle measurement feedback information. Firstly, the output angle measurement signal characteristics of the two types of sensors when they fail are given.

[0170] Furthermore, the specific implementation method of step S2 includes the following steps:

[0171] S2.1. Construct the output angle measurement signal characteristics of the induction synchronizer when the actuator fails during on-orbit operation;

[0172] S2.1.1. Considering that the induction synchronizer uses a continuous winding and a sinusoidal signal to excite, and the segmented winding outputs the potential, and works in the amplitude detection mode, the excitation circuit generates an excitation signal E that changes sinusoidally with time, which is expressed as:

[0173] E=E 0 sinωt

[0174] Among them, E 0 represents the amplitude of the excitation signal, ω represents the angular frequency of the excitation signal, and t represents time;

[0175] The excitation signal is directly applied to the continuous winding end of the induction synchronizer. The A and B phase segmented windings of the induction synchronizer are orthogonal in space, so that the A phase potential E of the induction synchronizer is induced on the two phase windings respectively. A 、B-phase potential E of the induction synchronizer B , the expression is:

[0176]

[0177] Among them, k A , k B It represents the voltage transfer ratio between the primary and secondary windings of the induction synchronizer;

[0178] S2.1.2. Set the A-phase potential E of the induction synchronizer A 、B-phase potential E of the induction synchronizer B After passing through the signal amplification circuit, it is input into the second processing circuit box, and the obtained A phase signal is U A , B phase signal is U B , the expression is:

[0179]

[0180] Among them, G A , G B Indicates the amplification factor of the signal amplifier circuit;

[0181] When the induction synchronizer is working normally, the amplification factor of the signal amplifier circuit ensures that the signal U input to the second processing circuit box is A , U B The maximum amplitude of is consistent, denoted by E m , the expression is:

[0182]

[0183] S2.1.3. Based on the induction synchronizer operating in the amplitude detection mode, the output of the signal amplification circuit in the second processing circuit box is connected to the function transformer to obtain two new potential signals U of phase A and phase B. A ',U B ', the expression is:

[0184]

[0185] in, is the adjustable and measurable variable in the function transformer. The two new potential signals are superimposed by the adder to obtain the total output potential U, which is expressed as:

[0186]

[0187] When the induction synchronizer rotates to any certain position αD , by adjusting the variable Until the output potential U points to zero, record the current variable The value of the current electrical angle α D The measured value is obtained, and then the mechanical angle α of the current position is obtained according to the relationship between the mechanical angle and the electrical angle of the induction synchronizer. The expression is:

[0188] α D =Pα

[0189] Where P represents the number of pole pairs of the induction synchronizer, which completes the measurement of the current angle;

[0190] S2.1.4. Analyze the information characteristics of the induction synchronizer measurement results when the excitation power supply fails during on-orbit operation:

[0191] The excitation circuit open circuit fault means that there is no excitation signal input at all, then the total output potential U is 0, and the total output potential measured is a series of noise, α D The actual measured value is a series of noise and is related to the measured value at the previous moment, which depends on the dynamic tracking speed of the angle measurement;

[0192] If the excitation circuit of the induction synchronizer is open and there is no excitation signal input, the total output potential U is 0. That is to say, from the occurrence of this type of fault, no matter where the induction synchronizer is, no matter how the variable is adjusted The total output potential U is 0 or, more precisely, we can only measure the total output potential as a series of noise, then α D The actual measured value is a series of noise, and the measured value at this moment is related to the measured value at the previous moment, which depends on the dynamic tracking speed of the angle measurement of the decoding system. This is the information characteristic of the measurement result of the induction synchronizer when the excitation circuit is open.

[0193] S2.1.5. Analyze the information characteristics of the induction synchronizer measurement results when the signal amplifier circuit is open-circuited during on-orbit operation:

[0194] If one phase signal amplifier circuit of the induction synchronizer is open, the expression of the total output potential U is:

[0195]

[0196] According to the expression, no matter where the induction synchronizer is, U points to zero. The expression is:

[0197]

[0198] The value of k depends on the position of the induction synchronizer at the time of the fault, and the value of α from the time when the signal amplifier circuit open circuit fault occurs is obtained.D The actual measured value is a constant value, which is the information characteristic of the measurement result of the induction synchronizer when the signal amplification circuit is open;

[0199] S2.2. Construct the output angle measurement signal characteristics of the absolute grating encoder when the actuator fails during on-track operation;

[0200] During actual on-orbit operation, the most frequent problem is the photoelectric reading head. After being affected by the environment, the photodiodes in it can no longer be sensitive to the light signal after passing through the matrix encoder grating. That is, no matter how the encoder is rotated, the photoelectric reading head can only read the signal when the light intensity is the weakest. It is not difficult to find that as long as at least one photoelectric reading head fails to work properly, the feedback angle measurement value will definitely show discontinuous characteristics near the position where the error occurs, and at least half of the feedback angle measurement value will no longer be accurate. This is the information feature of the matrix encoder measurement result caused by the failure of the photoelectric reading head.

[0201] S2.2.1. The absolute grating encoder is arranged in a matrix, and operates in a combination of 8 photoelectric reading heads, a 12-bit coarse angle measurement channel with 2-circle code channels, and a fine angle measurement channel with a 16-bit subdivision angle measurement function;

[0202] S2.2.2. The rough angle measurement channel is encoded with Gray code. Eight photoelectric reading heads are evenly placed on the first circle of code tracks to convert the optical signal into a pulse electrical signal. The relationship between the eight optical signals a of the first circle and the first four bits of Gray code A is:

[0203]

[0204] in, It means that the optical signal a is negated;

[0205] On the second circle code channel, eight-quadrant matrix encoding is used, and eight photoelectric reading heads are evenly placed on a 360° circumference. The Gray code is obtained by the relationship between the eight optical signals of the second circle and the last eight bits of Gray code, and then decoded by the first processing circuit box to obtain the corresponding coarse channel angle measurement value, which is expressed as:

[0206]

[0207] S2.2.3. The sine signal and cosine signal output by the photoelectric reading head of the fine angle measurement channel are converted into 16-bit A / D, and the fine channel angle measurement value within the coarse channel angle measurement resolution is calculated after being converted into digital signals. The coarse channel angle measurement value and the fine channel angle measurement value obtained in step S2.2.2 are combined to obtain the final angle measurement result output by the absolute grating encoder;

[0208] S2.2.2. Set the absolute grating encoder to be a photoelectric reading head failure when the actuator is running on track. When at least one photoelectric reading head fails to work properly, the feedback angle measurement value shows a non-discontinuous feature near the position where the error occurs, and obtain the output angle measurement signal characteristics of the absolute grating encoder when the actuator fails to run on track;

[0209] Once a sensor fails, whether it is only the inductive synchronizer that fails, the matrix encoder that fails, or even both of them fail at the same time, the information characteristics of the angle measurement results caused by different faults are almost completely different, so Δα′ is no longer within the threshold. Therefore, we only need to compare the two angle measurement results of the dual sensors to determine whether there is an angle measurement device that has failed. However, it is unreasonable to assume that an angle measurement device has failed simply because a large Δα′ has appeared, because the measurement circuit is always accompanied by accidental external interference signals. Considering that the failure of the angle measurement device must be irreversible damage, it is considered to extend the timeline for detecting the fault. S2.3. Construct the output angle measurement signal characteristic Δα′ when the actuator fails during on-orbit operation, and the expression is:

[0210] Δα′=α 1 -α 2

[0211] Among them, α 1 Indicates the angle of the induction synchronizer at a certain moment, α 2 Indicates the angle of the absolute grating encoder at a certain moment;

[0212] When Δα′ is no longer within the set threshold range, it is preliminarily judged that the actuator has a fault in orbit operation; then take n 1 sampling points, when it is determined that there are n 2 If the sampling points satisfy the following relationship, it is judged that a fault in the angle measuring device is detected, and the expression is:

[0213]

[0214] Among them, p 0 The confidence level is manually set;

[0215] After the fault is detected, the cause of the fault needs to be further analyzed. The main difficulty in diagnosing the fault is that once the current sensor is judged to be faulty, the cause of the fault cannot be directly determined. Therefore, neither the induction synchronizer nor the absolute grating is completely reliable at this time. To solve this problem, a fault diagnosis method based on open-loop operation is proposed according to the working principle of the control torque gyro.

[0216] At present, the actuators in the controlled torque gyroscopes are permanent magnet synchronous motors in most cases. In addition to the advantages of high efficiency, high power density, low noise, high control performance and reliability, the permanent magnet synchronous motor has another very important property: the speed of the permanent magnet synchronous motor is strictly equal to the speed of the stator rotating magnetic field;

[0217] Right now

[0218]

[0219] Therefore, as long as the number of pole pairs of the permanent magnet synchronous motor in the control torque gyro is known, given a known stator magnetic field power-on frequency, the motor will rotate at a constant speed, and the speed can be calculated. Therefore, combined with the sampling frequency of the sensor, two sets of one-to-one corresponding angle true value and angle measurement result data are obtained, and an angle true value-angle measurement result image can be drawn with the angle true value as the horizontal coordinate and the sensor angle measurement result as the vertical coordinate. This is the key step we use to perform fault diagnosis.

[0220] S2.4. Construct a fault diagnosis method based on open-loop operation based on the working principle of the control moment gyro;

[0221] S2.4.1. Using the method of step S2.3, determine whether the inductive synchronizer and the absolute grating encoder have failed according to the true angle value and the angle measurement result. When it is determined that the inductive synchronizer has failed, proceed to step S2.4.2. When it is determined that the absolute grating encoder has failed, proceed to step S2.4.3.

[0222] S2.4.2. First, determine whether the current fault is caused by an open circuit in the excitation circuit based on whether the angle measurement signal after the fault is periodic; use the method in step S2.3 to verify the periodicity of the angle measurement result. When the induction synchronizer rotates to the same position twice and the angle measurement result exceeds the threshold, the fault is caused by an open circuit in the excitation circuit;

[0223] When the induction synchronizer rotates to the same position twice and the angle measurement result is periodic, check whether the fault is caused by the open circuit of the signal amplifier circuit. The judgment standard is that the angle measurement result is a constant value. Record the most recent N 3 The angle measurement result at the sampling point α 5 , and calculate the mean of the angle measurements Find this N 3 The number of data points that do not satisfy the following formula among the sampling points is N 4 , the expression is:

[0224]

[0225] Among them, p 3is a confidence level set artificially. If N 3 、N 4 、p 3 If the following relationship is satisfied, it is considered that the angle measurement result of the induction synchronizer of this fault is a constant value. The cause of the fault is diagnosed as an open circuit in the signal amplifier circuit. The expression is:

[0226]

[0227] S2.4.3. The fault caused by the absolute grating encoder is a fault in which the photoelectric reading head cannot receive the light-sensitive signal. The judgment basis is that the absolute grating encoder fault detection confidence is not less than 0.5 and the angle measurement result is periodic. If the above conditions are met, the absolute grating encoder is diagnosed as having a fault.

[0228] Further explanation is as follows:

[0229] First, we need to determine whether the induction synchronizer and absolute grating have failed based on the two sets of data, the true angle value and the angle measurement result. The test methods for both are the same. For a certain sensor, the number of sampling points of the sensor in one cycle is N. 1 , subtract the angle measurement results of these sampling points from the true angle, and compare them with the error threshold to find the number of points N where the angle measurement error is large 2 , p1 is an artificially set confidence level.

[0230]

[0231] This sensor is considered to have failed. Whether it is an induction synchronizer or a matrix encoder, this method can be used to determine whether it has failed.

[0232] If the diagnosis result is that the induction synchronizer has failed. The two fault characteristics of the induction synchronizer are quite clear. After the fault caused by the open circuit of the excitation circuit occurs, the angle measurement result is a series of noise sequences that are only related to the measurement value at the previous moment. In other words, even if the induction synchronizer rotates to the same position twice, its angle measurement results may not be consistent. Therefore, it is possible to determine whether the current fault is this type of fault based on whether the angle measurement signal after the fault is periodic. Here, the periodicity of the angle measurement result can still be verified by detecting the fault. The number of sampling points in one cycle is recorded as N 1 , respectively extract the angle measurement result sequence α within two periods 3 , α 4 , subtract the angle measurement results of the same position in two cycles, and compare them with the error threshold to find the number of points N where the angle measurement error is large 2 , p 2 is a confidence level set artificially. If N1 、N 2 、p 2 The following relationship is satisfied

[0233]

[0234] It is believed that the angle measurement result of the induction synchronizer of this fault does not have the periodicity with a period of 360 mechanical degrees, and the cause of the fault is diagnosed as an open circuit in the excitation circuit.

[0235] If the test result shows that the angle measurement result of the faulty induction synchronizer is periodic, then it is necessary to check whether the fault is caused by an open circuit in the signal amplifier circuit. When an open circuit fault occurs in the signal amplifier circuit, the signal characteristic is that the angle measurement result is a constant value. Record the most recent N 3 The angle measurement result at the sampling point α 5 , and calculate the mean of its angle measurements Find this N 3 The number of data points that do not satisfy the following formula is N 4 ;

[0236]

[0237] p 3 is a confidence level set artificially. If N 3 、N 4 、p 3 The following relationship is satisfied

[0238]

[0239] It is considered that the angle measurement result of the induction synchronizer with this fault is a constant value, and the fault cause is diagnosed as an open circuit of the signal amplifier circuit. After the above steps, if the fault cause of the induction synchronizer is still not diagnosed, it is considered that other faults have occurred, resulting in the abnormal operation of the induction synchronizer.

[0240] If the result of the diagnosis is that the matrix encoder has a fault, it is mainly necessary to detect whether the photoelectric reading head cannot receive the light-sensitive signal. When this type of fault occurs, the signal characteristics of the angle measurement result of the sensor are that the angle measurement result is discontinuous near the point where the measurement error occurs, and at least half of the angle measurement results deviate far from the true value of the angle. At the same time, it is not difficult to see that even if this type of fault occurs, the angle measurement result of the sensor should still maintain a periodicity with a mechanical angle of 360 degrees as a period. Therefore, there are two main diagnostic criteria for this type of fault: first, the confidence level p1 of the matrix encoder fault detection is not less than 0.5; second, the angle measurement result is periodic. If these two conditions are met, it can be diagnosed that the cause of the fault at this time is that the photoelectric reading head cannot be normally sensitive to the light signal. If the cause of the matrix encoder fault is still not diagnosed, it is considered that other faults have occurred, resulting in the abnormal operation of the matrix encoder.

[0241] The above gives the information characteristics of the angle measurement results when the two sensors fail when the dual sensor fault diagnosis and online calibration device is running on orbit, and the corresponding diagnostic mathematical method is given accordingly. If the above major fault occurs, the information will be fed back to the ground in time. If the above major fault does not occur, on-orbit compensation can be performed.

[0242] S3. For a major fault diagnosed, feedback of the major fault information obtained in step S3 is sent to the host computer;

[0243] S4. For those diagnosed as having no major faults, use the induction synchronizer to perform online detection and compensation of the angular measurement error to complete the online error calibration of the actuator.

[0244] Furthermore, the specific implementation method of step S4 includes the following steps:

[0245] S4.1. Establish the actual online angle measurement error angle Δα of the induction synchronizer D ′, the expression is:

[0246] Δα D ′=Δα D0 +Δα D1 +Δα D2 +Δα Dc +ε

[0247] Among them, Δα Dc is the online compensation angle, and the expression is:

[0248]

[0249] Among them, α A , α B , α C They respectively represent the corresponding compensation coefficients of the online errors to be identified;

[0250] Substituting in:

[0251]

[0252] Based on the above formula, we get Δα D , α D All are detectable quantities, set Δα D0 +α A , Δε-ΔU+α C is the online parameter to be identified;

[0253] S4.2. For the α obtained in step S4.1 A , α B , α C Real-time adjustment based on the results of online identification; the compensation coefficient is adjusted once every 1 second, and the compensation coefficient after the kth compensation is α A (k), α B (k), α C (k), the compensation coefficient after the k+1th compensation is α A (k+1),α B (k+1),α C (k+1), then the k-th online parameter to be identified is Then the expression is:

[0254]

[0255] S4.3. Construct an online identification method using recursive memory-eliminating least squares method, and obtain The online identification expression of is:

[0256]

[0257] Among them, λ represents the forgetting factor of the gradual memory method, K represents the gain matrix, P represents the covariance matrix, and y represents the measurement error matrix. represents the operation matrix;

[0258]

[0259] Considering the induction synchronizer working in a slow time-varying system (continuous parameter change) and a sudden change system (discontinuous parameter change), simulation verification is performed to compare the angle measurement error of the induction synchronizer when using this scheme and when not using this scheme. Figure 3-Figure 8 As shown:

[0260] For slow time-varying systems, Figure 3When this solution is not used, the angular measurement error of the induction synchronizer changes with time. It can be seen that the angular measurement error is gradually diverging, which will cause a significant decrease in the angular measurement accuracy of the induction synchronizer over time. Figure 4 After using the online compensation solution, the angular measurement error of the inductive synchronizer changes with time. It can be seen that the error is accurately identified and compensated in real time, and the angular measurement accuracy is always maintained within a reliable range. Figure 5 It represents the identification value of each component of the induction synchronizer angular measurement error after online compensation. It can be seen that each error component is almost close to 0 after compensation, indicating that the angular measurement accuracy of the induction synchronizer is good.

[0261] For mutation systems, Figure 6 When this solution is not used, the angular measurement error of the induction synchronizer changes with time. It can be seen that the sudden change in the system will also cause a sudden change in the angular measurement error of the induction synchronizer, resulting in instability in the angular measurement accuracy. Figure 7 After using the online compensation solution, the angular measurement error of the inductive synchronizer changes with time. It can be seen that the sudden angular measurement error will be identified and compensated in a short time, so that the accuracy of the inductive synchronizer can quickly return to a higher level. Figure 5 It represents the identification value of each component of the induction synchronizer angular measurement error after online compensation. It can be seen that except for the high angular measurement error component when a sudden change occurs, each error component is almost close to 0 after being compensated in a short time, indicating that the angular measurement accuracy of the induction synchronizer can still return to a good level.

[0262] The above gives a mathematical method for online compensation of the angle measurement error of the induction synchronizer using the angle measurement feedback of the absolute grating when there is no major fault. And through simulation, it is verified that the recursive gradual memory method can significantly improve the angle measurement accuracy of the induction synchronizer, whether it is a time-varying system with discontinuous parameter changes or a slow time-varying system with continuous parameter changes, and the online identification compensation adjustment effect is significant.

[0263] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0264] Although the present application has been described above with reference to specific embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural conflict, the various features in the specific embodiments disclosed in the present application may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A dual-sensor based spacecraft actuator fault diagnosis and online calibration device, characterized in that: It comprises an absolute grating encoder (1), an actuator expansion shaft (2), an inductive synchronizer (3), a control torque gyro (4), a photoelectric reading head (5), a signal amplifying circuit (6), an exciting power supply (7), a first processing circuit box (8), a second processing circuit box (9), and a host computer (10); An absolute grating encoder (1), an inductive synchronizer (3) and a control torque gyro (4) are coaxially mounted via an actuator extension shaft (2), one end of the actuator extension shaft (2) is connected to the absolute grating encoder (1), the other end of the actuator extension shaft (2) is connected to the inductive synchronizer (3), and the inductive synchronizer (3) is connected to the control torque gyro (4); The absolute grating encoder (1) is connected to a first processing circuit box (8) via a photoelectric reading head (5) wire, and the first processing circuit box (8) is connected to a host computer (10); The induction synchronizer (3) is connected to a signal amplifying circuit (6) and an excitation power supply (7) respectively through wires, the signal amplifying circuit (6) is connected to a second processing circuit box (9) through wires, and the second processing circuit box (9) is connected to a host computer (10).

2. A dual-sensor based spacecraft actuator fault diagnosis and online calibration device according to claim 1, characterized in that: The photoelectric signal of the absolute grating encoder (1) is read by a photoelectric reading head (5) in two ways, namely, coarse and fine, and then connected to a first processing circuit box (8) to be converted into an angle value feedback and fed back to the host computer.

3. A dual-sensor based spacecraft actuator fault diagnosis and online calibration device according to claim 2, characterized in that: The induction synchronizer (3) is single-phase excited by an exciting power supply (7), and the obtained two-phase output signal is first connected to a signal amplification circuit (6), and after the amplified signal is connected to a second processing circuit box (9), converted into an angle value feedback, and fed back to the host computer.

4. A method for fault diagnosis and online calibration of a spacecraft actuator based on dual sensors, implemented by a device for fault diagnosis and online calibration of a spacecraft actuator based on dual sensors as claimed in any one of claims 1 to 3, characterized in that: The steps include: S1. When the actuator is located on the ground, the parameters to be identified of the induction synchronizer are constructed, the angle measurement error of the induction synchronizer is calibrated once, the angle measurement feedback of the absolute grating encoder is used as the angle measurement reference, the parameters to be identified of the angle measurement error of the induction synchronizer are identified offline, and then the identification results are compensated using the offline compensation method to complete the offline error calibration of the actuator; S2. Based on the on-orbit operation of the actuator, the output angle measurement signal characteristics of the induction synchronizer when the actuator fails to operate on-orbit are constructed, and the output angle measurement signal characteristics of the absolute grating encoder when the actuator fails to operate on-orbit are constructed for fault judgment, and then a fault diagnosis method based on open-loop operation is constructed based on the working principle of the control moment gyro to diagnose major faults. If a major fault is diagnosed, step S3 is executed, and if no major fault is diagnosed, step S4 is executed; S3. For a major fault diagnosed, feedback of the major fault information obtained in step S3 is sent to the host computer; S4. For those diagnosed as having no major faults, use the induction synchronizer to perform online detection and compensation of the angular measurement error to complete the online error calibration of the actuator.

5. A method for fault diagnosis and online calibration of spacecraft actuators based on dual sensors according to claim 4, characterized in that: The specific implementation method of step S1 includes the following steps: S1.

1. Based on the fact that the main error of the induction synchronizer is the secondary component and DC component of the current electrical angle, the actual angle error angle Δα of the induction synchronizer is established D , the expression is: Da D =Da D0 +Da D1 +Da D2 +e Among them, Δα D0 The DC component angle of the induction synchronizer’s angular error, Δα D1 Indicates the error angle caused by the inaccurate scale of the induction synchronizer itself and the non-orthogonality of the two phases, Δα D2 It represents the error angle caused by the unequal amplitude of the two phases of the exciting power supply and the non-orthogonal phase, and ε represents the measurement noise; Establishing Δα D1 The expression is: Among them, Δα represents the adjacent orthogonal error angle of the two-phase windings, Δε represents the adjacent amplitude error angle of the two-phase windings, and α D Indicates the current electrical angle of the induction synchronizer; Establishing Δα D2 The expression is: in, It represents the phase error between the two phases of the exciting power supply, and ΔU represents the amplitude error between the two phases of the exciting power supply; Δα D1 and Δα D2 The actual angle measurement error Δα of the induction synchronizer D The expression of is: Known Δα D , α D All are detectable quantities, set Δα D0 , Δε-ΔU is the parameter to be identified of the induction synchronizer; S1.

2. Using the one-time least square method, based on the parameters to be identified of the induction synchronizer obtained in step S1.4, the angle measurement error of the induction synchronizer is calibrated once, and the expression is: in, represents the matrix of parameters to be identified, Φ represents the matrix composed of operation results, and Y represents the matrix composed of measurement values; The expression is: The expression of Φ is: Among them, α D (N) represents the electrical angle position of the Nth induction synchronizer; The expression of Y is: Among them, Δα D (N) represents the angle measurement error value of the Nth electrical angle of the induction synchronizer; S1.

3. Take the angle measurement feedback of the absolute grating encoder as the angle measurement reference, evenly select 23 test points within the full 360-degree range, record the feedback angle measurement values ​​of the induction synchronizer and the absolute grating encoder at the corresponding test points, and make a difference between the feedback angle measurement values ​​of the induction synchronizer and the absolute grating encoder to obtain Δα at each location. D The value of; the matrix composed of the measured values ​​is brought into the offline identification of the parameters to be identified of the induction synchronizer angle measurement error by the one-time least square method, and the identification result is obtained, which is expressed as: Among them, A, B, and C represent the identification results corresponding to the amplitudes of the error components to be compensated; S1.

4. Use the offline compensation method to compensate the identification result obtained in step S1.3, denoted by α D is the current electrical angle position of the induction synchronizer, then the calculation formula for the actual angle measurement angle α′ of the induction synchronizer is:

6. A method for fault diagnosis and online calibration of spacecraft actuators based on dual sensors according to claim 5, characterized in that: The specific implementation method of step S2 includes the following steps: S2.

1. Construct the output angle measurement signal characteristics of the induction synchronizer when the actuator fails during on-orbit operation; S2.1.

1. Considering that the induction synchronizer uses a continuous winding and a sinusoidal signal to excite, and the segmented winding outputs the potential, and works in the amplitude detection mode, the excitation circuit generates an excitation signal E that changes sinusoidally with time, which is expressed as: E=E0 sinωt Where, E0 represents the amplitude of the excitation signal, ω represents the angular frequency of the excitation signal, and t represents time; The excitation signal is directly applied to the continuous winding end of the induction synchronizer. The A and B phase segmented windings of the induction synchronizer are orthogonal in space, so that the A phase potential E of the induction synchronizer is induced on the two phase windings respectively. A 、B-phase potential E of the induction synchronizer B , the expression is: Among them, k A , k B It represents the voltage transfer ratio between the primary and secondary windings of the induction synchronizer; S2.1.

2. Set the A-phase potential E of the induction synchronizer A 、B-phase potential E of the induction synchronizer B After passing through the signal amplification circuit, it is input into the second processing circuit box, and the obtained A phase signal is U A , B phase signal is U B , the expression is: Among them, G A , G B Indicates the amplification factor of the signal amplifier circuit; When the induction synchronizer is working normally, the amplification factor of the signal amplifier circuit ensures that the signal U input to the second processing circuit box is A , U B The maximum amplitude of is consistent, denoted by E m , the expression is: S2.1.

3. Based on the induction synchronizer operating in the amplitude detection mode, the output of the signal amplification circuit in the second processing circuit box is connected to the function transformer to obtain two new potential signals U of phase A and phase B. A ',U B ', the expression is: in, is the adjustable and measurable variable in the function transformer. The two new potential signals are superimposed by the adder to obtain the total output potential U, which is expressed as: When the induction synchronizer rotates to any certain position α D , by adjusting the variable Until the output potential U points to zero, record the current variable The value of the current electrical angle α D The measured value is obtained, and then the mechanical angle α of the current position is obtained according to the relationship between the mechanical angle and the electrical angle of the induction synchronizer. The expression is: α D ＝Pα Where P represents the number of pole pairs of the induction synchronizer, which completes the measurement of the current angle; S2.1.

4. Analyze the information characteristics of the induction synchronizer measurement results when the excitation power supply fails during on-orbit operation: The excitation circuit open circuit fault means that there is no excitation signal input at all, then the total output potential U is 0, and the total output potential measured is a series of noise, α D The actual measured value is a series of noise and is related to the measured value at the previous moment, which depends on the dynamic tracking speed of the angle measurement; S2.1.

5. Analyze the information characteristics of the induction synchronizer measurement results when the signal amplifier circuit is open-circuited during on-orbit operation: If one phase signal amplifier circuit of the induction synchronizer is open, the expression of the total output potential U is: According to the expression, no matter where the induction synchronizer is, U points to zero. The expression is: The value of k depends on the position of the induction synchronizer at the time of the fault, and the value of α from the time when the signal amplifier circuit open circuit fault occurs is obtained. D The actual measured value is a constant value, which is the information characteristic of the measurement result of the induction synchronizer when the signal amplification circuit is open; S2.

2. Construct the output angle measurement signal characteristics of the absolute grating encoder when the actuator fails during on-track operation; S2.2.

1. The absolute grating encoder is arranged in a matrix, and operates in a combination of 8 photoelectric reading heads, a 12-bit coarse angle measurement channel with 2-circle code channels, and a fine angle measurement channel with a 16-bit subdivision angle measurement function; S2.2.

2. The rough angle measurement channel is encoded with Gray code. Eight photoelectric reading heads are evenly placed on the first circle of code tracks to convert the optical signal into a pulse electrical signal. The relationship between the eight optical signals a of the first circle and the first four bits of Gray code A is: in, It means that the optical signal a is negated; On the second circle code channel, eight-quadrant matrix encoding is used, and eight photoelectric reading heads are evenly placed on a 360° circumference. The Gray code is obtained by the relationship between the eight optical signals of the second circle and the last eight bits of Gray code, and then decoded by the first processing circuit box to obtain the corresponding coarse channel angle measurement value; S2.2.

3. The sine signal and cosine signal output by the photoelectric reading head of the fine angle measurement channel are converted into 16-bit A / D, and the fine channel angle measurement value within the coarse channel angle measurement resolution is calculated after being converted into digital signals. The coarse channel angle measurement value and the fine channel angle measurement value obtained in step S2.2.2 are combined to obtain the final angle measurement result output by the absolute grating encoder; S2.2.

2. Set the absolute grating encoder to be a photoelectric reading head failure when the actuator is running on track. When at least one photoelectric reading head fails to work properly, the feedback angle measurement value shows a non-discontinuous feature near the position where the error occurs, and obtain the output angle measurement signal characteristics of the absolute grating encoder when the actuator fails to run on track; S2.

3. Construct the output angle measurement signal characteristic Δα′ when the actuator fails during on-orbit operation, and the expression is: Δα′=α1-α2 Among them, α1 represents the angle of the angle measurement result of the induction synchronizer at a certain moment, and α2 represents the angle of the angle measurement result of the absolute grating encoder at a certain moment; When Δα′ is no longer within the set threshold range, it is preliminarily determined that the actuator has a fault in orbit; then n1 sampling points are taken within a period of time. When it is determined that n2 sampling points satisfy the following relationship, it is determined that a fault has been detected in the angle measuring device. The expression is: Among them, p0 is the confidence level set manually; S2.

4. Construct a fault diagnosis method based on open-loop operation based on the working principle of the control moment gyro; S2.4.

1. Using the method of step S2.3, determine whether the inductive synchronizer and the absolute grating encoder have failed according to the true angle value and the angle measurement result. When it is determined that the inductive synchronizer has failed, proceed to step S2.4.

2. When it is determined that the absolute grating encoder has failed, proceed to step S2.4.

3. S2.4.

2. First, determine whether the current fault is caused by an open circuit in the excitation circuit based on whether the angle measurement signal after the fault is periodic; use the method in step S2.3 to verify the periodicity of the angle measurement result. When the induction synchronizer rotates to the same position twice and the angle measurement result exceeds the threshold, the fault is caused by an open circuit in the excitation circuit; When the induction synchronizer rotates to the same position twice and the angle measurement result is periodic, check whether the fault cause is the open circuit of the signal amplifier circuit. The judgment standard is that the angle measurement result is a constant value. Record the angle measurement results α5 at the most recent N3 sampling points and calculate the average value of the angle measurement. Find out the number of data points that do not satisfy the following formula among the N3 sampling points, which is N4. The expression is: Among them, p3 is a confidence level set artificially. If the following relationship is satisfied among N3, N4, and p3, it is considered that the angle measurement result of the induction synchronizer of this fault is a constant value. The cause of the fault is diagnosed as an open circuit in the signal amplifier circuit. The expression is: S2.4.

3. The fault caused by the absolute grating encoder is a fault in which the photoelectric reading head cannot receive the light-sensitive signal. The judgment basis is that the absolute grating encoder fault detection confidence is not less than 0.5 and the angle measurement result is periodic. If the above conditions are met, the absolute grating encoder is diagnosed as having a fault.

7. A method for fault diagnosis and online calibration of spacecraft actuators based on dual sensors according to claim 6, characterized in that: The specific implementation method of step S4 includes the following steps: S4.

1. Establish the actual online angle measurement error angle Δα of the induction synchronizer D ′, the expression is: Da D ′=Da D0 +Da D1 +Da D2 +Da Dc +e Among them, Δα Dc is the online compensation angle, and the expression is: Among them, α A , α B , α C They respectively represent the corresponding compensation coefficients of the online errors to be identified; Substituting in: Based on the above formula, we get Δα D , α D All are detectable quantities, set Δα D0 +α A , Δε-ΔU+α C is the online parameter to be identified; S4.

2. For the α obtained in step S4.1 A , α B , α C Real-time adjustment based on the results of online identification; the compensation coefficient is adjusted once every 1 second, and the compensation coefficient after the kth compensation is α A (k), α B (k), α C (k), the compensation coefficient after the k+1th compensation is α A (k+1),α B (k+1),α C (k+1), then the k-th online parameter to be identified is Then the expression is: S4.

3. Construct an online identification method using recursive memory-eliminating least squares method, and obtain The online identification expression of is: Among them, λ represents the forgetting factor of the gradual memory method, K represents the gain matrix, P represents the covariance matrix, and y represents the measurement error matrix. represents the operation matrix;

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