Sliding Mode Controller for Force Constrained Cutting Process

The characteristics of the computer numerical controlled cutting process can be described by a nonlinear dynamical system in the presence of the parameter variation. When the cutting operation proceeds, process model parameters can be changed in response to the machining requirements. This may lead the system to the bad machining performance or instability. On the basis of the variable structure system theory, a sliding mode controller has been designed for regulating the cutting force during machining. A piecewise linear feedback control law results in the error states `sliding´ along a switching plane. The independence of this plane upon the machining parameters makes the overall system insensitive to the fast and wide variations in the cutting conditions. Compared with the other schemes, the sliding mode controller can reduce large overshoots which occur at the instant of the step change of parameters and its control law is readily implemented.