An optimal algorithm for angular speed approximation using incremental encoders

Ingeniería e Investigación Journal, 2013

ABSTRACT
In this paper we propose a new algorithm that uses the signals coming from an incremental encoder to approximate the speed of a rotating shaft. This algorithm eliminates the oscillations that appear in the classical fixed-time and fixedspace algorithms, even when the speed is constant. A fixed-time algorithm measures angular displacement at fixed time intervals, while the fixed-space algorithm measures time every fixed-angular displacement. Time and displacement measurements are used to generate estimations of the speed. The new algorithm generates a unique value for the approximation of the speed due to the synchronization of the encoder pulses and a signal formed by impulses every time increment (delta). A first modification of the proposed algorithm is defined, and the result is that the harmonic mean between these two proposed alternatives has the smallest relative error possible. This error is always smaller than half the error with fixed-time and fixed-space algorithms. Finally, the experimental setup and algorithms are shown, as well as the results of the execution in Simulink using signals acquired from an incremental encoder.