Improving the velocity sensing resolution of pulse encoders by FIR prediction

An FIR (finite impulse response) predictor based approach is presented to increase the highest possible velocity sampling rate of a cycle-length measuring based velocity feedback system. The proposed method improves the slow-speed characteristics of optical pulse encoders in applications where the angular velocities down to about 0.5 RPM are of interest. The proposed principle works well in elevator control applications where the approximate shape of the low-speed curve is a second order polynomial. However, the same principle with an appropriate set of predictor coefficients can be applied to more general velocity sensing applications, as well