Calibration, Compensation and Accuracy Analysis of Circular Grating Used in Single Gimbal Control Moment Gyroscope

Abstract

The accuracy of the circular grating is the key point for control precision of the single gimbal control moment gyroscope servo system used in civilian micro-agile satellites. Instead of using the multi reading heads to eliminate eccentricity errors, an algorithm compensation method based on a calibration experiment using a single reading head was proposed to realize a low-cost and high accuracy angular position measurement. Moreover, the traditional hardware compensation method using double reading heads was also developed for comparison. Firstly, the single gimbal control moment gyroscope system of satellites was introduced. Then, the errors caused by the installation of the reading head were studied and the mathematic models of these errors were developed. In order to construct the compensation function, a calibration experiment using the autocollimator and 24-sided prism was performed. Comparison of angle error compensation using the algorithm and hardware method was presented, and results showed that the algorithm compensation method proposed by this paper achieved the same accuracy level as the hardware method. Finally, the proposed method was further verified through a control system simulation.

Study of a measurement system and a method for determining the distance between the grooves of a hydraulic valve

“…The valve part is measured n times; each time, the angle is increased by 2π n around the 0 axis, and the n installation measurements are evenly distributed. The measured results satisfy equation (13), and the data is substituted into the binary nonlinear overdetermined equation ( 14) to yield φ and…”

“…Chen et al developed an error model using multibody systems theory for angular measurements with geometric errors made by a torsional-characteristic-measurement system, as an attempt to delve into the impact of geometric errors on angular measurement and remedy measurement errors [12]. Instead of using multiple reading heads to eliminate eccentricity errors, Yu et al proposed a calibration experiment-based compensation algorithm method with a single reading head to measure angular position in a low-cost and high-accuracy manner [13]. Jia et al presented a method for measuring radial error motion and detecting eccentricity based on a visual system and image-processing technology [14].…”

“…As compared with the single-reading-head method [13] or the multiple-reading-head method [11,15], the abovementioned method does not require the addition of any reading head, while it eliminates the installation step. Multibody systems theory [12] cannot detect the eccentricity of the shaft system, but the method presented in this paper can determine the eccentricity of the system.…”

Compensation of Rotary Encoders Using Fourier Expansion-Back Propagation Neural Network Optimized by Genetic Algorithm

“…Many methods have been developed to improve the angle measurement accuracy of the rotary encoder. The discrete angle measurement error values were obtained by the use of an autocollimator and a regular optical polygon to provide reference angle [1][2][3][4][5]. The eccentricity of the grating disk accounts for the majority of the angle measurement error.…”

“…The eccentricity of the grating disk accounts for the majority of the angle measurement error. An eccentricity error model was built, and angle measurement accuracy was improved by compensating the eccentricity error [1][2][3]. Gao et al analyzed the discrete values by fast Fourier transform (FFT) and calculated the constants with particle swarm optimization (PSO) to solve the problem of the non-convergence of the traditional least square method [4].…”