Robust control strategy for suppression of regenerative chatter in turning

Chatter suppression is of great importance in machining processes for achieving more material removal rate, high precision and surface quality. In this paper, an H∞H∞ control algorithm is proposed for chatter suppression in the presence of tool wear and parameter uncertainties. Orthogonal turning process is modelled as a single degree of freedom model that includes the effect of tool flank wear. Control input of the system is the force provided by a piezo-actuator. The turning process model includes the uncertainties in cutting velocity, tool wear and dynamic model parameters. Using the μμ-synthesis technique, an H∞H∞ optimal controller is designed based on a DK-iteration algorithm. The performance of this optimal controller is compared with a sliding mode controller. Both optimal robust and sliding mode controllers guarantee robust performance of the system against the uncertainties and result in the desired time responses of the vibration amplitude. Sliding mode control is able to achieve a faster response with less control effort. However, H∞H∞ robust control results in a more continuous and less oscillatory time response.