Precision Motion Control Methodology for Complex Contours

A general precision motion control methodology for complex contours is proposed in this paper. Each servomechanism dynamic model is divided into a linear portion and a portion containing nonlinear friction, unmodeled dynamics and unknown disturbances. A full state feedback controller, based on a state space error system model, is developed to track general reference trajectories. The lumped friction effects are described using the Tustin friction model. Unmodeled dynamics and disturbances are estimated using a Kalman filter that employs a first-order stochastic model. The nonlinear friction, unmodeled dynamics and disturbances are directly cancelled by the controller. Experiments are conducted on a two-axis laboratory grade machine tool for limacon and freeform contours. The results demonstrate the excellent tracking performance of the proposed motion control methodology.