Multifunction ActiveAerostatic Coupling for Ultraprecision Positioning System

为提高超精密定位系统的定位精度，提出了一种多功能主动式气体静压联轴器。这种空气静压联轴器的特征在于具有主动空气静压推力轴承，并且采用该联轴器的定位系统具有以下功能：（1）与驱动机构的振动隔离：驱动机构的横向振动产生几微米量级的工作台振动。采用空气静压联轴器，隔离了驱动机构的振动，使工作台振动降低到纳米量级。(2)推力刚度的提高：使用空气静压联轴器对于提高工作台运动精度是有效的，但是，进给驱动装置的推力刚度会有所降低。对联轴器中的气体静压推力轴承进行主动控制，实现了无限大的推力刚度。在10Hz的频率下，也可以看到主动控制对动态推力刚度的影响。(3)超精密定位：主动式空气静压联轴器具有短行程高分辨率定位功能。步进定位实验表明，主动式气浮耦合器的定位分辨率至少为50 μ m。耦合器还控制工作台的微旋转，数量级为μrad。这些功能是有效的，以提高定位性能的超精密定位系统中使用的纳米技术的几个领域，如超精密机床，超精密测量机，和步进LSI。

A multifunction active aerostatic coupling is proposed for improving the performance of ultraprecision positioning system. This aerostatic coupling is characterized to have an active aerostatic thrust bearing and the positioning system employing the coupling has following functions:(1) Isolation of vibration from the driving mechanism : Lateral vibration of the driving mechanism generates the table vibration in the order of several micrometers. By using the aerostatic coupling, the vibration of the driving mechanism is isolated and the table vibration is reduced to the nanometer order.(2) Improvement of thrust stiffness : The use of the aerostatic coupling is effective for improving the accuracy of the table motion, however, there occurs some decrease in the thrust stiffness of the feed drive device. Active control of the aerostatic thrust bearing in the coupling realizes the infinite thrust stiffness. The effect of the active control on the dynamic thrust stiffness can also be seen to the frequency of 10Hz.(3) Ultraprecision positioning: The active aerostatic coupling has the function of short-stroke positioning with high-resolution. The experiment of step positioning shows that the positioning resolution of the active aerostatic coupling is 50pm at least. The coupling also controls the micro rotation of the table in the order of μrad. These functions are effective for improving the positioning performance of the ultraprecision positioning system used in the several fields of nanotechnology, such as ultraprecision machine tool, ultraprecision measuring machine, and stepper for LSI.