An Improved Linearization Circuit Used for Optical Rotary Encoders

Measurement Science Review

Jovanović Uglješa¹  Denić Dragan²  Jovanović Jelena² 

[1] Department of Electronics, Faculty of Electronic Engineering, University of Niš, Aleksandra Medvedeva, 14, 18000, Niš, Serbia;Department of Measurements, Faculty of Electronic Engineering, University of Niš, Aleksandra Medvedeva, 14, 18000, Niš, Serbia;

关键词: angular position measurement;    linearization;    analog-to-digital conversion;    accuracy improvement;   

DOI  :  10.1515/msr-2017-0029

来源: DOAJ

【 摘 要 】

Optical rotary encoders generate nonlinear sine and cosine signals in response to a change of angular position that is being measured. Due to the nonlinear shape of encoder output signals, encoder sensitivity to very small changes of angular position is low, causing a poor measurement accuracy level. To improve the optical encoder sensitivity and to increase its accuracy, an improved linearization circuit based on pseudo-linear signal generation and its further linearization with the two-stage piecewise linear analog-to-digital converter is presented in this paper. The proposed linearization circuit is composed of a mixed-signal circuit, which generates analog pseudo-linear signal and determines the first four bits of the final digital result, and the two-stage piecewise linear analog-to-digital converter, which performs simultaneous linearization and digitalization of the pseudo-linear signal. As a result, the maximal value of the absolute measurement error equals to 3.77168·10−5 [rad] (0.00216°) over the full measurement range of 2π [rad].

【 授权许可】

Unknown