Implementation of a friction estimation and compensation technique

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 total friction present assuming it to be a constant times the sign of velocity. A second observer is used to estimate the velocity using the measured position of the rotating shaft in the apparatus, when 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 by the use of the estimated friction to compensate the system, especially at very low velocity.