An implementable approach in order to model a nonideal incremental encoder in speed measurement studies

Abstract

Incremental encoders have attracted significant attention to measure motor speed worldwide. Due to the advantages of incremental encoders a noticeable percentage of Servo system drives have been built based on these sensors. The nonideality of encoders, especially mechanical misalignments, is one of their most important problems, affecting the precision of calculations. In the current paper we present an analytical formula to model the nonideal incremental encoder and calculate both the frequency and magnitude of vibrations due to this nonideality. Moreover, a nonideality identity parameter of the encoder is defined. This parameter can be used for quality assurance purposes. Moreover, it is possible to design exible filters for measured speed based on this parameter, especially in low resolution encoders. The simulation and experimental results corroborate the precision of the proposed method in a wide range of speeds.