Driving process and control analysis in macro-micro dual stage

Abstract

This paper presents a macro-micro dual stage using hybrid actuators composed of voice coil motor (VCM) and piezoelectric actuator (PZT). Connecting coarse (driven by voice coil motor) and fine (actuated by the piezoelectric), in series, to achieve a large travel range and high precision positioning. In the structure of redundant actuation, the micro stage is applied to compensate the error generated by the macro stage. The compensating method of point-to-point (PTP) positioning is divided into two types: compensation before steady state (macro/micro single input dual output) and compensation before steady state (macro/micro dual input dual output). A corresponding driving process is described in each type. In the driving process, the interference behavior between macro stage and micro stage is considered and the dynamic coupling model established. In the process of control analysis, because of the saturation of micro stage, switching control plays an important role in realizing precision positioning. Mode switching control is achieved by using switching function according to the two types of positioning way. Finally, step response shows that the positioning accuracy of dual stage is higher than single macro stage, and also can realize nano-positioning.