Design of Precision Positioner with Hall-effect Sensors and Multivariable Control Methodology

摘要

This paper presents the design and multivariable feedback control of a compact precision positioner. The moving stage that has a total mass of 1.52 kg can generate all 6-axis motions with a single frame. Aerostatic bearings levitate the positioner and three 3-phase synchronous permanent-magnet planar motors (SPMPMs) generate electromagnetic forces over the concentrated-field permanent-magnet matrix. Three Hall-effect sensors measure the magnetic flux to calculate the planar position and three laser-distance sensors detect the vertical displacement. Real Time Application Interface (RTAI) with Comedi on a Linux personal computer is used for real-time control. Single-input single-output (SISO) digital lead-lag controllers for each axis are designed, and a multi-input multi output (MIMO) model is developed for the positioner. Reduced-order linear-quadratic-Gaussian (LQG) controllers are applied in horizontal positioning. Several experimental results demonstrate the dynamic performance of the positioner.