Milling Chatter Mitigation with Projection-Based Robust Adaptive Controller and Active Magnetic Bearing

Chatter vibration has been a critical phenomenon in milling, and results in poor surface finishes, severe tool wear and shrill noise, which are usually overcome with quite conservative cutting parameters and hence the machining efficiency is significantly affected. In order to suppress the chatter vibration and improve the machining efficiency of milling process, a milling chatter mitigation method is presented with projection-based robust adaptive controller and an active magnetic bearing (AMB) installed in the milling spindle. The AMB is utilized to apply the active force to stabilize the milling process when the originally selected cutting conditions are unstable, with which the chatter-free boundary can be enlarged. Considering the possible parameters' uncertainties of milling system which result from the nonlinear dynamic behaviors of the spindle system and the possible saturation of actuator caused by the noise, a projection-based robust adaptive controller is designed. Simulations of active chatter mitigation with different degrees of milling system's uncertainties are performed, and the results show that the boundary of stability lobes diagram (SLD) of milling chatter is significantly enlarged. In addition, the milling experiments are also performed with the AMB installed in a milling spindle, and the results show that the chatter vibration is exactly mitigated with the presented method in this paper.