Adaptive friction compensation for bi-directional low-velocity position tracking

A comparative investigation of friction-compensating control strategies designed to improve low-velocity reversals for servomechanisms is presented. The methods considered include adaptive control and estimation-based control. The various controller designs incorporate different friction models ranging from classical friction and Stribeck friction to the less popular Dahl friction model. The control strategies are compared in an extensive test program involving sinusoidal position trajectory tracking experiments on a direct-drive DC motor. The results show that the adaptive and estimation-based controllers outperform more traditional linear controllers. It is also shown that the Dahl model, typically ignored in the literature, is significant for the friction-compensating control problem with repeated zero-velocity crossings.>