A calibration and compensation system for resolver harmonic errors based on rate gyroscope

Abstract

The present invention relates to a rotary transformer harmonic error calibration and compensation system based on a rate gyro, comprising: a servo control unit, an error evaluation unit, an error calibration unit, and an error compensation unit; the servo control unit is used to control the load to stably rotate according to the command angular velocity. The error evaluation unit sends the command angular velocity to the control servo control unit, performs spectrum analysis on the rotary transformer angular velocity output by the servo controller, and transmits the error harmonic order N obtained by the spectrum analysis to the error calibration unit and the error compensation unit as a basis for adjusting error calibration and error compensation. The error calibration unit accurately calibrates the rotary transformer angular measurement error with a harmonic order of N from the difference between the angular velocity measured by the rate gyro and the angular velocity measured by the rotary transformer, and obtains the error sine and error cosine. The error compensation unit reconstructs the error according to the error sine and error cosine obtained by the error calibration unit, and performs error compensation on the original angular position output by the rotary transformer.

Description

Technical Field

[0001] The invention relates to a resolver harmonic error calibration and compensation system. Background Art

[0002] The rotary transformer has high reliability and good adaptability to mechanical and thermal environments, and is widely used in the field of high-precision angle measurement in aerospace.

[0003] The resolver obtains the envelope of the two amplitude modulated signals through detection, and then uses a demodulation algorithm to obtain the angular position information. Ideally, the envelope signal after detection should be an orthogonal sine and cosine signal, but due to factors such as the asymmetric amplitude of the transformer output signal, non-ideal orthogonality, inductor harmonics, and phase offset of the carrier reference signal, the envelope signal after detection often contains DC bias, amplitude asymmetry, and phase offset. Coupled with the demodulation error of the demodulation chip, the resolver produces a certain angle measurement error.

[0004] The demodulation errors of the resolver mainly include amplitude error, quadrature error and function error. The frequency of amplitude error and quadrature error is twice the frequency of the rotation frequency, while the frequency of function error is twice the frequency of the rotation frequency and its higher harmonics. In addition, the uneven winding of the stator and rotor magnetic sheets of the resolver will also produce frequency errors related to the number of stator and rotor magnetic sheets.

[0005] In summary, the main components of the rotary transformer angular measurement error are the inconsistency, non-orthogonality and waveform distortion (function error) of the rotary transformer excitation sine and cosine signals, which are reflected in the angular velocity as the second and higher harmonic errors of the rotation frequency, which seriously affect the demodulation accuracy of the rotary transformer, and then affect the control accuracy of the servo system, and need to be compensated. The existing rotary transformer error compensation method is mainly based on the calibration method, using a high-precision angular position sensor to measure the angular measurement error of the rotary transformer at different angular positions, and making an angular measurement error lookup table for compensation. This compensation method requires the purchase of an ultra-high-precision angular position sensor, and requires the compensated rotary transformer to have a mechanical transfer interface and design an ultra-high-precision transfer tooling to install an ultra-high-precision angular measurement sensor. The assembly accuracy requirements are extremely high. Using this method to compensate for the high-order harmonic error of the rotary transformer must be precisely traced, the process is complicated, and online compensation cannot be performed, which is inconvenient to use. Summary of the invention

[0006] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and provide a resolver harmonic error calibration and compensation system based on a rate gyroscope, which corrects the angular measurement error caused by the non-equal amplitude, non-orthogonality and waveform distortion (function error) of the sine and cosine signals output by the resolver, which is reflected in the angular velocity as the secondary and higher harmonics of the resolver's rotation frequency, improves the angular measurement accuracy of the resolver, and further improves the control accuracy of the servo system. The system is suitable for high-precision correction and compensation of the harmonic errors of the resolver, and is suitable for correction and compensation of the angular measurement errors of the resolver, and can greatly improve the angular measurement accuracy of the resolver.

[0007] The technical solution adopted by the present invention is:

[0008] A rate gyro-based resolver harmonic error calibration and compensation system comprises: a servo control unit, an error evaluation unit, an error calibration unit, and an error compensation unit;

[0009] The servo control unit includes a servo controller, a servo motor, a load, a rate gyro, a resolver, a resolver demodulator and a differentiator; the resolver and the rate gyro are both installed on the load; the servo control unit receives the command angular velocity of the error evaluation unit, uses the rate gyro to obtain the load angular velocity, controls the load to rotate at a steady speed, transmits the obtained resolver angular velocity to the error evaluation unit, and transmits the obtained resolver angular position to the error calibration unit and the error compensation unit;

[0010] The error evaluation unit sends a command angular velocity to the servo control unit, performs spectrum analysis on the resolver measurement angular velocity output by the servo controller, and transmits the error harmonic order N obtained by the spectrum analysis to the error calibration unit and the error compensation unit;

[0011] The error calibration unit uses the correlation integration method to accurately calibrate the angle measurement error of the resolver with harmonic order N from the difference between the gyro angular velocity and the resolver angular velocity, and obtains the error sine and error cosine.

[0012] The error compensation unit reconstructs the error according to the error sine quantity and the error cosine quantity obtained by the error calibration unit, and performs error compensation on the measured angular position θ output by the resolver demodulator.

[0013] Furthermore, in the servo control unit, the resolver demodulator demodulates the sine and cosine signals output by the resolver to obtain the measured angular position θ, and obtains the resolver angular velocity Vel_RDC after passing through the differentiator; the rate gyro measures the angle in a direction parallel to the rotation axis of the resolver, and measures the load angular velocity to obtain the gyro angular velocity Vel_Gyro; the servo controller calculates and outputs the control current to the servo motor based on the difference between the command angular velocity Vel_zl output by the error evaluation unit and the gyro angular velocity Vel_Gyro; the servo motor outputs a torque based on the control current to drive the load to track the command angular velocity Vel_zl.

[0014] Furthermore, it is assumed that the error evaluation unit sends a command angular velocity Vel_zl to the servo control unit, and the servo controller is ordered to rotate at a constant speed, and a spectrum analysis is performed on the measured angular velocity Vel_RDC.

[0015] Error harmonic order

[0016] Among them, f N is the frequency of the main spectral component of the measured angular velocity Vel_RDC.

[0017] Further, it is assumed that the gyro angular velocity Vel_Gyro and the resolver angular velocity Vel_RDC sent by the resolver demodulator received by the error calibration unit are difference processing to obtain the resolver angular velocity measurement error Vel_RDC_e, and then high-pass filtering is performed by a high-pass filter to obtain the filtered resolver angular velocity measurement error Vel_RDC_e_filter.

[0018] Further, the error calibration unit receives the resolver angular position θ sent by the resolver demodulator, multiplies it by the error harmonic order N to obtain Nθ, performs sine-cosine transform on Nθ to obtain sin(Nθ) and cos(Nθ), and multiplies it with the filtered resolver angular velocity measurement error Vel_RDC_e_filter to obtain:

[0019]

[0020]

[0021] Then the harmonic error compensation coefficients A_sin and A_cos are obtained after low-pass filtering through a low-pass filter and sent to the error compensation unit.

[0022] Furthermore, the high-pass filter is a second-order Butterworth high-pass filter, whose cut-off frequency is less than 0.1×f N .

[0023] Furthermore, the low-pass filter is a second-order Butterworth low-pass filter, whose cut-off frequency is less than 0.1×f N .

[0024] Furthermore, it is assumed that the measured angular position sent by the resolver demodulator received by the error compensation unit is θ, multiplied by the error harmonic order N, and then Nθ is transformed into sin(Nθ) and cos(Nθ); the harmonic error compensation coefficients A_sin and A_cos obtained by the error calibration unit are divided by the error harmonic order N, and then divided by the command angular velocity Vel_zl used during calibration, and multiplied by cos(Nθ) and sin(Nθ) respectively, and the difference is obtained. The sum of the measured angular position θ output by the rotary transformer is then taken to compensate for the measured angular position θ.

[0025] The beneficial effects of the present invention compared with the prior art are:

[0026] (1) The present invention discloses an error calibration unit, which uses a rate gyro for speed feedback to complete the speed closed loop of a servo controller, and uses the difference between the rate gyro and the resolver to calibrate the resolver angular measurement error. The rate gyro does not need to be coaxial with the resolver, but only needs to be parallel, and the rate gyro has low installation accuracy requirements.

[0027] (2) The present invention discloses an error evaluation unit, which evaluates the error size of the resolver according to the amplitude of the higher harmonics in the spectrum analysis result of the angular velocity measurement of the resolver during constant speed rotation, thereby realizing the evaluation of the harmonic error size of the resolver angular measurement.

[0028] (3) The present invention discloses an error compensation unit, which performs open-loop compensation for the angle measurement harmonic error of the rotary transformer without affecting the stability of the servo control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the structural diagram of the rate gyro-based resolver harmonic error calibration and compensation system;

[0030] Figure 2 This is the structure diagram of the error calibration unit;

[0031] Figure 3 This is the structural diagram of the error compensation unit. DETAILED DESCRIPTION

[0032] The present invention is described in detail below with reference to the accompanying drawings.

[0033] like Figure 1 As shown, the present invention discloses a rate gyro-based resolver harmonic error calibration and compensation system, comprising four units:

[0034] The servo control unit receives the command angular velocity from the error evaluation unit, obtains the load angular velocity using the rate gyro, controls the load to rotate at a steady speed, transmits the obtained resolver angular velocity to the error evaluation unit, and transmits the obtained resolver angular position to the error calibration unit and the error compensation unit.

[0035] The error evaluation unit sends the command angular velocity to the control servo control unit, performs spectrum analysis on the resolver angular velocity output by the servo controller, and transmits the error harmonic order N obtained by the spectrum analysis to the error calibration unit and the error compensation unit as the basis for adjusting the error calibration and error compensation. The angle measurement error of the resolver is evaluated based on the harmonic amplitude in the spectrum analysis.

[0036] The error calibration unit uses the correlation integration method to accurately calibrate the angle measurement error of the resolver with harmonic order N from the difference between the gyro angular velocity and the resolver angular velocity, and obtains the error sine and error cosine.

[0037] The error compensation unit reconstructs the error according to the error sine quantity and the error cosine quantity obtained by the error calibration unit, and performs error compensation on the measured angular position θ output by the resolver demodulator.

[0038] 1. Servo control unit

[0039] like Figure 1 As shown, the servo control unit includes a servo controller, a servo motor, a load, a rate gyro, a resolver, a resolver demodulator, and a differentiator; the resolver is installed on the load, and the resolver demodulator demodulates the sine and cosine signals output by the resolver to obtain the measured angular position θ, and obtains the resolver angular velocity Vel_RDC after passing through the differentiator; the rate gyro is installed on the load, and the measuring angle direction is parallel to the rotating axis of the resolver, and the load angular velocity is measured to obtain the gyro angular velocity Vel_Gyro; the servo controller calculates and outputs a control current to the servo motor based on the difference between the command angular velocity Vel_zl output by the error evaluation unit and the gyro angular velocity Vel_Gyro; the servo motor outputs a torque based on the control current to drive the load to track the command angular velocity Vel_zl;

[0040] 2. Error evaluation unit

[0041] The error evaluation unit sends the command angular velocity Vel_zl to the servo control unit, which makes the servo controller rotate at a constant speed and performs spectrum analysis on the measured angular velocity Vel_RDC. N Calculate the error harmonic order N:

[0042]

[0043] And according to f N The frequency spectrum amplitude at is used to obtain the angle measurement error of the rotary transformer; at the same time, the error harmonic order N is sent to the error calibration unit and the error compensation unit.

[0044] 3. Error calibration unit

[0045] like Figure 2 As shown,

[0046] The error calibration unit receives the gyro angular velocity Vel_Gyro and the resolver angular velocity Vel_RDC sent by the resolver demodulator, performs difference processing on them, obtains the resolver angular velocity measurement error Vel_RDC_e, and then passes through a high-pass filter (a second-order Butterworth high-pass filter with a cutoff frequency less than 0.1×f N) is high-pass filtered to obtain the filtered resolver angular velocity measurement error Vel_RDC_e_filter.

[0047] The error calibration unit receives the resolver angular position θ sent by the resolver demodulator, multiplies it by the error harmonic order N, obtains Nθ, performs sine and cosine transform on Nθ to obtain sin(Nθ) and cos(Nθ), and multiplies it with Vel_RDC_e_filter to obtain

[0048]

[0049]

[0050] Then it passes through a low-pass filter (a second-order Butterworth low-pass filter with a cutoff frequency less than 0.1×f N ) is low-pass filtered to obtain the harmonic error compensation coefficients A_sin and A_cos, which are then sent to the error compensation unit.

[0051] 4. Error compensation unit

[0052] like Figure 3 As shown, the error compensation unit receives the resolver measurement angular position θ sent by the resolver demodulator, multiplies it by the error harmonic order N, and then performs sine-cosine transform on Nθ to obtain sin(Nθ) and cos(Nθ); the harmonic error compensation coefficients A_sin and A_cos obtained by the error calibration unit are divided by the error harmonic order N, and then divided by the command angular velocity Vel_zl used during calibration, and multiplied by cos(Nθ) and sin(Nθ) respectively to obtain the difference:

[0053]

[0054] The sum of the measured angular position θ output by the resolver is then taken to compensate for the resolver measured angular position θ.

[0055] The compensation system of the present invention can correct the angular measurement error caused by the non-equal amplitude, non-orthogonality and waveform distortion (function error) of the sine and cosine signals output by the rotary transformer, which is reflected in the angular velocity as the secondary and higher harmonics of the rotary transformer rotation frequency, thereby improving the angular measurement accuracy of the rotary transformer and further improving the control accuracy of the servo system. It is suitable for high-precision correction and compensation of the harmonic errors of the rotary transformer and for correction and compensation of the angular measurement errors of the rotary transformer, and can greatly improve the angular measurement accuracy of the rotary transformer.

[0056] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A rate gyro-based resolver harmonic error calibration and compensation system, characterized in that: include: Servo control unit, error evaluation unit, error calibration unit, error compensation unit; The servo control unit includes a servo controller, a servo motor, a load, a rate gyro, a resolver, a resolver demodulator and a differentiator; the resolver and the rate gyro are both installed on the load; the servo control unit receives the command angular velocity of the error evaluation unit, uses the rate gyro to obtain the load angular velocity, controls the load to rotate at a steady speed, transmits the obtained resolver angular velocity to the error evaluation unit, and transmits the obtained resolver angular position to the error calibration unit and the error compensation unit; The error evaluation unit sends a command angular velocity to the servo control unit, performs spectrum analysis on the resolver measurement angular velocity output by the servo controller, and transmits the error harmonic order N obtained by the spectrum analysis to the error calibration unit and the error compensation unit; The error calibration unit uses the correlation integration method to accurately calibrate the angle measurement error of the resolver with harmonic order N from the difference between the gyro angular velocity and the resolver angular velocity, and obtains the error sine and error cosine. The error compensation unit reconstructs the error according to the error sine quantity and the error cosine quantity obtained by the error calibration unit, and performs error compensation on the measured angular position θ output by the resolver demodulator; Assume that the gyro angular velocity sent by the resolver demodulator received by the error calibration unit is Vel_Gyro, and the resolver angular velocity is Vel_RDC, and perform difference processing on them to obtain the resolver angular velocity measurement error Vel_RDC_e, and then obtain the filtered resolver angular velocity measurement error Vel_RDC_e_filter after high-pass filtering; The error calibration unit receives the resolver angular position θ sent by the resolver demodulator, multiplies it by the error harmonic order N to obtain Nθ, performs sine-cosine transform on Nθ to obtain sin(Nθ) and cos(Nθ), and multiplies it by the filtered resolver angular velocity measurement error Vel_RDC_e_filter to obtain: Then the harmonic error compensation coefficients A_sin and A_cos are obtained after low-pass filtering through a low-pass filter and sent to the error compensation unit.

2. The rate gyro-based resolver harmonic error calibration and compensation system according to claim 1, characterized in that: In the servo control unit, the resolver demodulator demodulates the sine and cosine signals output by the resolver to obtain the measured angular position θ, and obtains the resolver angular velocity Vel_RDC after passing through the differentiator; the rate gyro measures the angle direction parallel to the rotating axis of the resolver, and measures the load angular velocity to obtain the gyro angular velocity Vel_Gyro; the servo controller calculates and outputs the control current to the servo motor based on the difference between the command angular velocity Vel_zl output by the error evaluation unit and the gyro angular velocity Vel_Gyro; the servo motor outputs torque based on the control current to drive the load to track the command angular velocity Vel_zl.

3. The rate gyro-based resolver harmonic error calibration and compensation system according to claim 2, characterized in that: Assume that the error evaluation unit sends a command angular velocity Vel_zl to the servo control unit, instructs the servo controller to rotate at a constant speed, and performs spectrum analysis on the measured angular velocity Vel_RDC. Error harmonic order Among them, f N is the frequency of the main spectral component of the measured angular velocity Vel_RDC.

4. The rate gyro-based resolver harmonic error calibration and compensation system according to claim 1, characterized in that: The high-pass filter is a second-order Butterworth high-pass filter with a cut-off frequency less than 0.1×f N .

5. The rate gyro-based resolver harmonic error calibration and compensation system according to claim 1, characterized in that: The low-pass filter is a second-order Butterworth low-pass filter with a cut-off frequency less than 0.1×f N .

6. The rate gyro-based resolver harmonic error calibration and compensation system according to claim 3, characterized in that: Assume that the measured angular position sent by the resolver demodulator received by the error compensation unit is θ, multiplied by the error harmonic order N, and then Nθ is transformed into sin(Nθ) and cos(Nθ); the harmonic error compensation coefficients A_sin and A_cos obtained by the error calibration unit are divided by the error harmonic order N, and then divided by the command angular velocity Vel_zl used during calibration, and multiplied by cos(Nθ) and sin(Nθ) respectively, and the difference is obtained. The sum of the measured angular position θ output by the rotary transformer is then taken to compensate for the measured angular position θ.

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