A Sliding-Mode Control Approach in Ultra-Precision Positioning System

It is known that the time optimal control seeks a target position faster than sliding-mode control. However, the time optimal control is vulnerable to chattering effect more than sliding-mode control. Especially for the nanometric scale positioning system under the parameter uncertainty and external disturbances, this can cause an actuator saturation. To solve this problem, we present the design of a robust optimal controller for an ultra-precision positioning stage. The control algorithm is a sliding-mode approach based on linear quadratic optimal control. Some simulation results are examined to demonstrate the effectiveness of the proposed controller.