Autocorrection of interpolation errors in optical encoders

Chunhai Wang; Guoxiong Zhang; Shangqi Guo; Jing Jiang

doi:10.1117/12.240896

30 May 1996 Autocorrection of interpolation errors in optical encoders

Chunhai Wang, Guoxiong Zhang, Shangqi Guo, Jing Jiang

Proceedings Volume 2718, Smart Structures and Materials 1996: Smart Sensing, Processing, and Instrumentation; (1996) https://doi.org/10.1117/12.240896
Event: 1996 Symposium on Smart Structures and Materials, 1996, San Diego, CA, United States

Abstract

The accuracy of optical encoders is usually limited by interpolation errors. A new design for eliminating these errors is presented. Its distinguished features are: (1) Gratings having sine function transmissivity are used as the index gratings, and as a result the harmonic errors of encoder signals are greatly reduced with the total amount of harmonic components less than 1%. A new method for producing sine index grating of various kinds is also investigated. (2) Non-orthogonal error, unequal amplitudes in the two interpolation signals and their residual dc voltages are corrected in real time by a specially designed error compensator. Non-orthogonal error is reduced to less than plus or minus 1 degree, inequality in amplitudes of the two signals less than plus or minus 2% and residual dc voltages less than plus or minus 20 mv. (3) An easy method for evaluating the interpolation errors without using reference instruments is proposed. Experiments show that a rotary encoder by using the sine index grating and the error compensator could meet the accuracy requirement for interpolation to 0.26% of the encoder's constant.

Citation Download Citation

Chunhai Wang, Guoxiong Zhang, Shangqi Guo, and Jing Jiang "Autocorrection of interpolation errors in optical encoders", Proc. SPIE 2718, Smart Structures and Materials 1996: Smart Sensing, Processing, and Instrumentation, (30 May 1996); https://doi.org/10.1117/12.240896

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