This paper presents a unique precision miniature platform for fine position
ing and compliant motion. This platform is implemented by using magnetic le
vitation forces of permanent magnets and air-core solenoids in pairs. In ad
dition, this platform has a moving-magnet type configuration that is advant
ageous in small magnetic systems. Since magnetic levitation systems are inh
erently unstable, the mechanical structure of the platform is designed to a
ssure dynamic stability and to have simple dynamics. For positioning of the
platform, a combined robust controller consisting of a model reference con
trol and a H-infinity control is proposed. Positioning experimental results
show that the performances of this control system may well be applied to f
ine manipulation and micro-assembly. A compliant motion, instead of a force
control, is also implemented with a feedforward-proportional-derivative co
ntrol, of which the performance is presented in terms of a force repeatabil
ity and seems to be satisfactory. (C) 2001 Published by Elsevier Science Lt
d.