Modeling and robust adaptive control of metal cutting mechanical systems

In turning metal cutting, the occurrence of self-excited vibration, so called chatter, is undesirable as it gives rise to production problems, causing detrimental effects on the machined surface finish and decreasing the machining efficiency. Rather than using the commonly accepted linear Merchant model, the relationship of cutting force variation and chip thickness variation is treated as a hysteresis model, which has been proved to be able to explain the nonlinearity of the turning metal cutting process in a way that is much more accurate. In this case, the turning cutting systems can be described as a class of uncertain systems with hysteresis and time delay. A robust adaptive control scheme for the suppression of chatter occurrence due to the existence of hysteresis and time delay in metal cutting is proposed and the novelty is that the hysteresis model is first incorporated into the controller design for a metal cutting system. Simulation results show significant reduction of chatter by the proposed adaptive controller.