Modified IMC Technique for Nonlinear Uncertain Milling CNC Machine Tool System

The objective of this paper is to model a nonlinear computer numerical control machine tool (CNCMT) system for milling process. A modified internal model control (M-IMC) technique is proposed for position control of machine table. The study of milling process is mainly focused on the cutting mechanics and dynamics. The performance of CNCMT system is degraded due to the presence of disturbance like cutting force and parametric uncertainty. Considering the limitation of conventional internal model control (C-IMC) technique that is the poor performance under constant disturbance, an M-IMC technique is designed for the rejection of disturbance and position control of uncertain nonlinear CNCMT system. The performances of nonlinear uncertain CNCMT system using M-IMC technique is also compared with C-IMC and Ziegler–Nichols-tuned proportional–integral–derivative control techniques. The proposed M-IMC technique is designed to attain the better disturbance rejection capability, i.e., regulatory control with less control effort for the regulation of desired position of a machine table.