为提高超精密定位平台的行程和精度,设计了一种新型的气动伺服定位平台。金属波纹管为单级驱动机构,采用有限元法设计气浮导轨。以气浮导轨支撑,研究无摩擦条件下的较大行程和精密控制。结合实验数据对波纹管的机械特性进行分析。根据初载曲线,进行参数辨识,建立了基于PI模型的定位平台系统迟滞模型,并对模型进行了验证。为改善系统动态特性,设计了复合控制器。前馈控制基于PI逆模型进行设计,反馈控制采用数字PID控制,并通过粒子群算法进行参数优化。对系统分别进行阶跃响应,锯齿波和正弦波跟踪实验。结果表明,参数优化后,系统阶跃响应的定位精度达到50 nm,平均跟踪误差,锯齿波输入为0.12μm,正弦波输入为0.18μm,能够满足超精密定位的要求。%In order to improve the stroke and precision of the ultra-precision positioning stage, a new type of pneumatic servo positioning stage was designed. Air bearing sliders were designed by finite element method and metal bellows were used as the single driving device in the positioning stage. The stage was supported by aerostatic sliders to realize large stoke and ultra-precision positioning. The mechanical char-acteristics of bellows were analyzed with the experimental data. According to the initial loading curve, the parameters were identified to establish the PI hysteresis model of the system, and the model was validated by the experiments. In order to improve dynamic performance of the system, a compound control scheme was designed. In this scheme,a feedforward controller was based on inverse PI model, and a PID control-ler was used as feedback controller, the parameters of the PID controller were optimized by particle swarm optimization. Experiments on the step signal, sawtooth signal and sine signal were implemented. After the parameters are optimized, the experimental results show that the positioning accuracy on the step re-sponse is less than 50nm, the average tracking error on sawtooth input signal is 0. 12μm, and the aver-age tracing error on sine input signal is 0. 18μm, the stage can meet the requirements of ultra-precision positioning.
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