The Dynamic Analysis of the Ultra-precision Positioning Stage with Air-levitated Bearings

摘要

To attain the ultra-precision motion of the air-levitated stage preventing from chaotic motion, the dynamical behavior of the ultra-precision stage with air-levitated bearings is studied theoretically and experimentally. Firstly, a setup is designed to research the dynamics and the positioning accuracy of the air levitated stage, which is dragged by a linear motor, and whose positions in three directions are detected by a laser interferometer. Then, the model of the air-levitated bearing is established by a single mode approximation using the Navier-stokes equation and the Newton equation.Furthermore, an new slide mode controller-MTSMC is provided for the stage to diminish the effects of unmodeled factors. Finally, the positioning accuracy analysis of the stage is carried out under the sequence step input. It is verified that the dynamics and positioning accuracy of the stage are largely affected by the nonlinear of air-levitated bearings, as well as the control method.Therefore the nonlinearity of the air-levitated bearing and method of controller should be taken into account when designing and manufacturing the ultra-precision positioning stage. The experimental results show that the positioning accuracy of the ultra-precision positioning stage with air-levitated bearing can reach 10 nm under the control of the SMC controller.