Trajectory following with a three-DOF micro-motion stage

Abstract

This paper presents the position control of a three-DOF (degree-of-freedom) micro-motion stage. This stage provides micro scale planar motion along the x and y axis and rotational motion along the z axis. It uses a 3 RRR (three revolute-revolute-revolute) °exure hinge based compliant mechanism driven by three piezo- electric stack actuators to achieve the micro motion along x, y and z axis. The micro-motion stage with operating frequency up to 1Hz is controlled to follow a prescribed circular tra- jectory. An analytical Jacobian of the stage is derived to relate the input displacements of the piezo-actuators to the output displacements of the stage. Closed-loop positioning control is achieved using the standard PI controller. The errors related to the position control along the x and y axis are presented.