Precision Positioning Control of Single-Axis Ultrasonic Actuating Stage by Using Neuro-Fuzzy Control Law

A novel single-axis ultrasonic actuating stage was designed. The stable and precise positioning control of a stage was achieved by using neuro-fuzzy controller. It consists of movable plate, edge-driving ultrasonic actuator as an actuating device, and magnetic Magi encoder as a position sensor. Through AD/DA servo control card, the dynamic signals and commands were processed under PC-base real-time system to implement the whole experiment setup. Since the nonlinearity, such as motion dead-zone and hysteresis, was inherent on this stage, the artificial knowledge control strategy was employed instead of the conventional transfer function methods. Thus, neuro-fuzzy controller completed positioning tasks and the exact nonlinear model was unnecessary for complicated ultrasonic actuating mechanical system. According to the experimental results, the positioning accuracy of stage system reached in 1.25 μm.