Original scientific paper
A Digital Speed Filter for Motion Control Drives with a Low Resolution Position Encoder
Armando Bellini
Stefano Bifaretti
Stefano Costantini
Abstract
In motion control drives, the motor rotation speed measurement is generally obtained by means of an incremental encoder with a limited number of counts per revolution. Since encoders furnish a shaft position measure, a derivative operation is needed to obtain a speed measure. As consequence, especially at lower speeds, the rotation speed measure results rather noisy and a suitable filter must be used to reduce the noise. After an overview on the speed measurement problems connected to the employment of an incremental encoder, the paper presents the algorithms of an original digital filter, based on a static Kalman filter; then, an efficient procedure for the implementation of such a filter on a 16-bit fixed point microcontroller is carried out. Proposed filter reduces the speed measurement noise to acceptable values and it can also provide an estimation of the acceleration. Finally, proposed filter has been employed on an industrial drive for machine tools.
Keywords
encoder; digital filter; drives; Kalman filter; speed measurement; transducers
Hrčak ID:
6760
URI
Publication date:
3.12.2003.
Visits: 5.849 *