Study Of 2-d Motion Stage Based On Laser Interferometric Sensing

In the modern industrial technology fields, especially, the fields of precision machining and precision measurement, there is an increasing demand of precision motion and positioning. 2-D motion stage is a core component of high-precision measurement systems and high-precision machining systems. It is composed of three parts, which are, motion machanism, displacement detection and motion control system. This dissertation focuses on the design of the motion machanism and the displacement sensing system of the stage.First, based on the research of the laser interferometry theory and key techniques, a single-frequency laser interferometer based on Michelson interferometer optical path is designed. It's interferogram is stable and clear. Selecting the Blue-ray converter which has high photoelectric conversion speed and efficiency, two orthogonal signals are available. Then a signal processing circuit is designed in order to eliminate the DC component, filter the noise, amplify the signals and so on. With this circuit, the orthogonal signals meet the interpolator's demand. The digital signals from the interpolator can been displayed on computer or delivered into the motor driver.Based on the analysis of the different types of michanical motion stages existing, a H-type air-bearing stage is designed, which is directly driven by linear motors. The designed aerostatic bearings adopt plane-closed structure. This structure has a gas film preload. The CFD software Fluent is applied to simulate the pressure field and static characteristic of the air film. Performance parameters like the pressure distribution of gas film, bearing capacity, stiffness of the bearings, are got and analyzed. And the structure parameters of air-bearings are optimally designed.Lastly, a linear motor-driven single-axis stage has been set up to do a step test for the project. The accuracy and stability of the sensing system are tested and the error sources are analyzed.