Adaptive sliding-mode control for a precision positioner with hybrid mechanism

This paper proposes a novel six-degree-of-freedom (DOF) electromagnetic precision positioner made of a hybrid mechanism utilizing both magnetic driving force and fluid upper lifting power, in which the new structure, the electromagnetic actuator, and the effective controller are developed. The concept of the mechanism design not only involves the magnetic driving mechanism but also the fluid buoyancy and damping properties, of which the latter help counter-balance weight of the platen so as to achieve very low steady-state power consumption. The four goals of novel system design include: (1) to have large moving range (in mm level), (2) to achieve precision positioning, (3) to design compact but low-cost mechanism, and (4) to achieve low power consumption. The experimental results show that traveling range is 3mmx3mmx4mm, and the tracking error in each axis is kept within 10 , which is up to the limitation of our optical sensors.