A velocity measurement method for acceleration control

TLDR

Accurate velocity information is essential for acceleration control in advanced motion systems, yet existing velocity measurement methods fail to achieve accuracy at high speeds. The authors introduce a novel synchronous velocity measurement method (S method) for motor drives equipped with optical encoders. The S method synchronizes velocity measurement with pulse number changes and, because it is model‑free, can be combined with other estimation techniques. The method delivers accurate velocity across all speed ranges, as confirmed by simulation and experimental validation.

Abstract

This paper proposes a novel method of velocity measurement for motor drives with optical encoders. Acceleration control is indispensable for advanced motion control while it requires accurate velocity information. Although many methods on velocity measurement have been proposed, accurate measurement was not achieved in a high-speed range. We therefore propose "synchronous measurement method (S method)" that measures the velocity synchronized with alteration of pulse numbers. Accurate velocity measurement is achieved in all speed ranges with this method. Furthermore, other estimation methods are applicable in addition since the method does not require any model of a control object. Simulation and experimental results verify the validity of the proposed method.