Abstract: In order to improve the accuracy and stroke of the ultra-precision positioning stage, a new type of pneumatic servo positioning stage with single driving device is designed. Metal bellows are used as driving device in the positioning stage, the stage is supported by air flotation sliders to realize large stoke and ultra-precision positioning. In order to reduce the number of operators and to improve modeling accuracy, hysteresis operators are modified to build the generalized PI model, and the model is validated too. A solution of the inverse generalized PI model is given. The compounding controller is designed based on inverse generalized PI model. Experiments are implemented on the step signal, sawtooth signal and multifrequency signal. The results show that the positioning accuracy of the step response is less than 30 nm, the average tracking errors on sawtooth and multifrequency input are 0.96 μm and 0.63 μm based on the PI model, and the average tracing errors are 0.49 μm,and 0.45 μm based on generalized PI model. Experiments show that the generalized PI model is effective for increasing the positioning accuracy of the stage.

Key words: bellows, compounding control, generalized hysteresis, ultra-precision