Design and implementation of an electromagnetically damped positioner with flexure suspension

In this paper, a novel design, control and implementation of a three degree-of-freedom (DOF) compact positioner is presented with high resolution in tens of nanometer-scale precision positioning and millimeter-level long travel range. According to the serial flexure mechanism design, whose motion comes from the elastic deformation of the flexure and the force allocation of five pairs of electromagnetic coils and permanent magnets, the precision positioner enables both horizontal and vertical actuations resulting in x-, y-, and z-motions respectively. Next, in order to improve the transient response and to suppress the vibration of the flexure suspension mechanism, an eddy current damper (ECD) is applied as a passive and noncontact resistance to vibration. Moreover, a laser interferometer sensing system is implemented to improve the positioning resolution of the stage. To maintain stability and robustness of the precision system, a decentralized adaptive sliding mode controller (DASMC) was implemented to overcome the overall situations of unmodeled system dynamics and external noises. From the experimental results, satisfactory performance has been observed, which means that the designated objectives of this research have been successfully attained, namely, (1)long working range, (2)high positioning resolution and (3)compact design.