Vibration suppression compensator using nonlinear observer for table positioning systems

To achieve high-speed, high-precision position control for semiconductor product machines and industrial robots, full-closed feedback control is applied. Many control methods have been proposed for such a system. In general, proportional position control and proportional plus integral velocity control or integral plus proportional velocity control (P, PI/I-P), which is a type of proportional plus integral plus deferential control (PID), is applied in many industrial applications. However, in the case of changing mechanical characteristics of the control target, the parameters of P, PI/I-PI control must also change or a disturbance observer is applied, to maintain good motion performance. In this paper, we propose a nonlinear observer to suppress the vibration for a table positioning system. The algorithm of the nonlinear observer is based on sliding mode control with chattering compensation. The effectiveness of the proposed observer is evaluated using a full-closed 2mass system model via point-to-point control in the case of changing load. The simulations and experiments indicate that the proposed observer is effective for vibration suppression in the case of changing load.