基于滑模变结构控制的气浮工作台定位精度仿真分析

The Positioning Accuracy Analysis of the Ultra-precision Stage with Air-thrust Bearings

气浮轴承存在明显的非线性的特性,而精密工作台又要求较高的精度,传统的PID控制方法较难满足系统定位精度的要求。在分析精密气浮平台工作原理的基础上,建立了气浮工作台直线运动的数学模型和基于滑模控制(SMC)的系统控制模型,并进行了参数分析和研究。研究结果表明,在受外界干扰较大,且存在较大非线性情况下,工作台仍能达到较好的定位精度,实现几十纳米的定位控制精度,证明了SMC控制器具有较好的鲁棒性。参数分析结果显示,气浮阻尼的存在有利于提高平台的定位精度。

For the request of ultra-precision of the positioning stage with air-thrust bearings and the outstanding nonlinearity of the stiffness coefficient of the air-thrust bearing, the traditional control methods, such as the PID controller, couldn＇t meet the needs of the ultra-precision positioning. This paper establishes the mathematic models of the linear motion stage with air-thrush bearing, and the system control model with SM C controller. The analysis of the parameters is carried out too. The results show that the SMC controller employs good robust; the stage system can reach high positioning precision （about several decade nanometers） even though there exists stronger disturbance in the system. And the parameter analysis shows that the existing of the air damp is useful to enhance the positioning accuracy.