Redundant and Flexible Pseudorandom Optical Rotary Encoder

Abstract

Optical encoders are mainly used in modern motion servo systems for high-resolution and reliable position and velocity feedback. Pseudorandom optical rotary encoders are single-track and use a serial pseudorandom binary code to measure absolute position. The realization and analysis of such a rotary encoder with advanced code scanning and error detection techniques, as well as an improved redundancy in operation, are presented. A presented serial code reading solution uses two phase-shifted code tracks and two optical encoder modules. So, the realized encoder, hybrid in nature, provides “output on demand” and more or less reliable position information using very efficient error checking. Compared to a standard absolute encoder, this encoder requires a smaller code disc, facilitates installation, has greater flexibility in operation, and is less sensitive to external influences.

Capacitive Angle Sensor Research Using COMSOL Multiphysics

“…Given the optical rotary encoder principle, absolute encoders are generally used for optical sensors, which are more complex than the incremental angle encoders used for other types rotary encoders [10]. However, its performance deteriorates in harsh environments [11]. Compared with optical rotary encoders, electromagnetic rotary encoders are more reliable, but they usually have permanent magnets set inside, which makes electromagnetic sensors vulnerable to interference from external magnetic fields [12].…”