On algorithms for velocity estimation using discrete position encoders

Velocity information for a rotating device may be acquired via a discrete position encoder. The focus of this paper is on analyzing and improving the low speed and high acceleration accuracy of velocity measurements through the use of digital filters for control applications. The frequency-domain characteristics of various digital filters that may be used to estimate velocity from pulse-encoded velocity data are investigated and used to explain the performance of the digital filters in estimating velocity for a given velocity profile. A new digital filter design technique based on an adaptive least squares approach is presented in addition to several previously developed fixed-time velocity estimators. The performance characteristics of these velocity estimators are compared using pulse-encoded velocity data from an actual motor.