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Proceedings Paper

Autocorrection of interpolation errors in optical encoders
Author(s): Chunhai Wang; Guoxiong Zhang; Shangqi Guo; Jing Jiang
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Paper 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.

Paper Details

Date Published: 30 May 1996
PDF: 9 pages
Proc. SPIE 2718, Smart Structures and Materials 1996: Smart Sensing, Processing, and Instrumentation, (30 May 1996); doi: 10.1117/12.240896
Show Author Affiliations
Chunhai Wang, Tianjin Univ. (China)
Guoxiong Zhang, Tianjin Univ. (China)
Shangqi Guo, Tianjin Univ. (China)
Jing Jiang, Tianjin Univ. (China)


Published in SPIE Proceedings Vol. 2718:
Smart Structures and Materials 1996: Smart Sensing, Processing, and Instrumentation
Kent A. Murphy; Dryver R. Huston, Editor(s)

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