Optimal arrangements of scanning heads for self-calibration of angle encoders

Abstract

The calibration of the angle encoder is necessary to improve the accuracy of angle measurement in precision rotating devices. Due to the characteristics of in situ calibration of encoders, self-calibration methods depending on special arrangements of multiple scanning heads have been widely used. Conventional works usually arrange the scanning heads in a regularly distributed way, generally involving too many scanning heads, especially when more high order Fourier components of the encoder error are calibrated. This paper presents an optimization-based arrangement method for self-calibration of angle encoders. Fourier approaches are used to determine the error of encoder from the angle differences measured between scanning heads. The relations between detectable Fourier components of the error and angular intervals of the heads are obtained from the properties of transfer functions. The optimal arrangements for two and three scanning heads, including the adjustment tolerances of the heads with the range of tested Fourier orders, are presented. The results of simulations and experiments demonstrate that the proposed optimal schemes can realize the same performance of calibration but with fewer scanning heads, compared to the conventional methods.

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

“…First, the compensation model of angle measurement error at each specific temperature is built by using Fourier expansion, as shown in Equation (13). Then the relationship between the coefficients of the Fourier series and ambient temperature is established by using of polynomial fitting separately, as shown in Equation (14). The orders of Fourier series are from 0 to 7, the degree of polynomial is 5.…”

“…The angle measurement error was decreased significantly [11][12][13]. The multi-reading heads were set in an irregularly distributed way and the transfer function was used to realize self-calibration of rotary encoder installed in the precise rotary table [14,15]. The researches mentioned above proposed many methods to correct the angle measurement error of the rotary encoder effectively without considering the effect of the ambient temperature.…”

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

“…(a) Most researchers have focused on the circular grating's accuracy of ground systems such as the articulated arm coordinate measuring machine (AACMM) and telescope control system. (b) Many scholars studied the compensation methods and self-calibration [27,28] of circular grating by multi reading heads. However, few research studies concerning the algorithm compensation can be found in recent years, and the comparison of the algorithm and hardware method has not been the focus of research on compensation of the circular grating.…”

Position Control of 1-DOF High-Precision Rotary Table using Adaptive Neuro-Fuzzy Inference System (ANFIS) Controller

“…The rotary table has been widely used in many areas such as synthetic aperture radar System (SAR) [1], industrial applications [2][3] [4][5] [6], calibration tools [7][8] [9], transportation systems [10] and so on. In order to get a satisfactory result, the rotary table has to meet high precision output which in this case is an accurate position of determined angle.…”