Coupled LQG with robust control for milling chatter suppression

This paper applies a coupled control method of LQG and robust to suppress milling chatter. With two controllers working together, the coupled control method has strong robustness to reject disturbances. According to this superiority, the time delay item caused by the regenerative effect is regarded as a disturbance for simplifying the system model. Thus the designed controller has a relatively smaller order than other time delay approximation or discretization methods. Based on the designed active control system, simulated results show the coupled control method has better performance than the original LQG and robust control methods. In experiments, the coupled control method improves the average critical cutting depth from 1.5 mm to 6 mm with almost the same control voltage as LQG and robust control methods, while they only improve the corresponding depth to 4.5 mm and 3.5 mm respectively. Furthermore, the stability improvement is also larger than a recently published control method used in milling chatter suppression. The largest stable milling region improvement among these methods shows potential of the coupled control method in milling chatter suppression.