Velocity estimation from widely spaced encoder pulses

It is often necessary to estimate the velocity of mechanical systems from the output of a digital encoder. Due to cost and/or noise problems, there maybe no direct velocity measurement available on such systems. Velocity reversal and sparseness of encoder signals are not handled well by traditional estimators. This paper proposes a transition logic based switching algorithm and an asynchronous multirate Luenberger observer based estimator to reduce these problems