Adaptive correction and look-up table based interpolation of quadrature encoder signals
ASME 2012 5th Annual Dynamic Systems and Control Conference Joint with the JSME 2012 11th Motion and Vibration Conference, DSCC 2012-MOVIC 2012
543 - 552
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Please cite this item using this persistent URLhttp://hdl.handle.net/11693/28117
This paper presents a new method to increase the available measurement resolution of quadrature encoder signals. The proposed method features an adaptive signal correction phase and an interpolation phase. Typical imperfections in the encoder signals including amplitude difference, mean offsets and quadrature phase shift errors are corrected using recursive least squares with exponential forgetting and resetting. Interpolation of the corrected signals are accomplished by a quick access look-up table formed offline to satisfy a linear mapping from available sinusoidal signals to higher order sinusoids. The position information can be derived from the conversion of the high-order sinusoids to binary pulses. With the presented method, 10nm resolution is achieved with an encoder having 1μm of original resolution. Further increase in resolution can also be satisfied with minimizing electrical noises. Experiment results demonstrating the effectiveness of the proposed method for a single axis and two axis slider systems are given. Copyright © 2012 by ASME.