Nonlinear friction compensation and disturbance observer for a high-speed motion platform

Nonlinear friction and external disturbances affect the positioning accuracy of high-speed motion systems, especially impelled by linear motor. Thus, how to eliminate theses disturbance should be considered when designing a robust controller. This paper presents a controller, which includes three parts: a proportional-plus-derivative (PD) feedback controller, a friction compensator, and a disturbance observer. The friction compensator is based on LuGre model and it compensates for nonlinear friction. The disturbance observer is used to eliminate the friction compensation error and other external disturbances. Experimental results show that the controller gives high positioning accuracy and more robust performance in the presence of disturbances.