Chatter suppression by adaptive speed modulation

In this paper a PD fuzzy logic controller is designed and implemented to suppress chatter in peripheral milling. The controller selects combinations of the amplitude and frequency of spindle speed modulation, online, to keep a chatter indicator, the R-value, close to a prescribed set point. The controller was successful in suppressing chatter at certain operating points. The effect of the control action delay time and the degree of process instability on the controller performance were addressed through simulations and experiments. At some operating points the controller resulted in an oscillatory behaviour of the process and the R-value fluctuated significantly. Stability lobes were used to explain this phenomenon. Strategies for enhancing the performance of the controller were proposed.