An active air journal bearing with ultraprecision, infinite static stiffness, high damping capability and new functions

Summary The aim of the paper is to develop an Active Air Journal Bearing (AAJB), AAJB is a rotary air bearing of a controlled type with following features: (1) ultra precision. (2) infinite static stiffness. (3) high vibration damping capability. (4) new functions such as the positioning of the rotating axis and the dynamics stiffness control. Such features are realized by positioning the axis with an active air bearing (AAB). AAB is composed of a static air bearing mechanism a non-contact sensor, a piezoelectric actuator, a controller and an objective mass to be controlled ie. the axis. First, the basic configuration of AAJB as well as its dynamic model and controller design is shown. Then the compliance and the axis positioning characteristics are examined. Finally the radial positions of the axis rotating at 1000rpm is controlled and the rotation accuracy of the axis less than 25nm is accomplished.