Abstract
The aim of this paper is to develop bearings which have the followings as their principal features : ultra-precision, non-contact, infinite stiffness and high damping capability. To accomplish these, the authors propose an “Active Air Journal Bearing” (AAJB) capable of precisely controlling the radial axis position. The AAJB utilizes non-contact sensors to detect the radial position of its axis, non-contact actuators (movable air pads driven by PZT actuators) to support and drive the axis, and a controller to regulate the whole system. The paper presents procedure for designing the controller parameters as well as method of analyzing the AAJB stiffness and the positioning characteristics. Some simulated and experimental results show that the AAJB has : (1) an almost infinite static stiffness and an increased damping capability, (2) a bandwidth of more than 1kHz and (3) a positioning accuracy better than 15nm.
