Research of miniature self-calibratable absolute rotary encoder kit: measurement error analysis and virtual emulation

Abstract

Self-calibrating modular type absolute rotary encoder kit was developed to offer a solution for applications where mounting space is extremely limited and high angular position measurement accuracy, and resolution are required. With the help of two combined optical sensors, the encoder`s scale eccentricity as well as the radial runout of the measured shaft errors are eliminated, and the installation requirements for the device are simplified. Theoretical and experimental research of the produced prototypes was performed to investigate properties of the considered encoder and analyse possible methods for further improvement of the device. In this work, ten manufactured encoders are cross-calibrated by using high-accuracy reference encoder and their angular position measurement error is determined. Performed harmonic analysis of the measured error distinguishes the Fourier components that have the greatest influence. The possibility of eliminating these harmonics by using several additional evenly spaced optical sensors is theoretically verified by virtual emulation of collected data. Considering the small dimensions of the device, the study analyses the cases where three and four optical sensors are used.