Accurate motion control of xy high-speed linear drives using friction model feedforward and cutting forces estimation

Accurate motion control is essential for machine tools. Both friction forces and cutting forces contribute to position and contour tracking errors. This paper presents a feedforward friction force compensation based on the Generalized Maxwell-slip (GMS) friction model that describes friction behaviour both in pre-sliding and sliding regime. An inverse-model-based disturbance observer is added to further improve the friction compensation. This disturbance observer is able to only partly reduce the effects of cutting forces. An almost complete elimination of these effects is obtained by adding a repetitive controller (RC). Experimental validations of these approaches on a linear-motor-based xy table are presented.