Implementation of a friction estimation and compensation technique

Abstract

A friction estimation and compensation technique was implemented on a laboratory apparatus designed to permit the direct measurement of friction. Experimental results are reported for a friction observer which estimates the total friction present, assuming that it is a constant times the sign of velocity. An second observer is used to estimate the velocity using the measured position of the rotating shaft in the apparatus, when the velocity is not measurable. Experimental results show that the friction estimate is consistent with the measured friction, displaying the theoretical hysteresis phenomenon. Moreover, the performance of the system is substantially improved, especially at very low velocity, through the use of the estimated friction to compensate the system.