Moving-magnet type precision miniature platform for fine positioning and compliant motion

Abstract

This paper presents a unique precision miniature platform for fine positioning and compliant motion. This platform is implemented by using magnetic levitation forces of permanent magnets and air-core solenoids in pairs. In addition, this platform has a moving-magnet type configuration that is advantageous in small magnetic systems. Since magnetic levitation systems are inherently unstable, the mechanical structure of the platform is designed to assure dynamic stability and to have simple dynamics. For positioning of the platform, a combined robust controller consisting of a model reference control and a H-infinity control is proposed. Positioning experimental results show that the performances of this control system may well be applied to fine manipulation and micro-assembly. A compliant motion, instead of a force control, is also implemented with a feedforward-proportional-derivative control, of which the performance is presented in terms of a force repeatability and seems to be satisfactory. (C) 2001 Published by Elsevier Science Ltd.