Self-adaptive control with hysteresis compensation on ultra-precision pneumatic servo stage

In this paper, one new type positioning stage is designed to improve the stroke and accuracy of ultra-precision positioning stage. The pneumatic metal bellows are used as a driving part, and the moving platform is supported with air guide sliders to realize larger stroke and ultra precision positioning with frictionless. The dynamic model of the system and the hysteresis model on the basis of PI model are provided and the corresponding parameters of PI model are optimized and identified according to the initial loading curve. Additionally, the self-adaptive controller with hysteresis compensation is designed to improve the dynamic characteristics of the system and the corresponding PID parameters are optimized according to the reference model. The experimental results with sawtooth signal and multiple frequency signals on the positioning stage show that, in the presence of the self-adaptive controller with hysteresis compensation, the maximum tracking error is 1.57μm and the average error is 0.77μm on sawtooth signal, while the maximum error is 0.92μm and the average error is 0.58μm on multiple frequency signal, so the proposed method can achieve high performance of the ultra-precision positioning.