A mechatronic approach to the control of machine tools

One of the most common sources of performance limitation in the control of machine tools is associated to the resonant dynamics of the drive train, induced by the elasticity in some components. The design of the control system should guarantee a damped behavior of the load position, both in the setpoint response and in the rejection of the disturbances arising from the machining operation. In this paper reference is made to the common P/PI control scheme, and stability analysis with adimensional parameters is first discussed. Tuning of the controller gains is then set as a problem of minimizing the H-inf norm of some closed loop transfer functions, for which closed form approximations are also given. The methodology is finally applied to the design of the control system for an axis of a milling machine, whose virtual prototype developed in the Dymola environment is also discussed.