Development and control methodologies for 2-DOF micro/nano positioning stage with high out-of-plane payload capacity

Two of the key issues to meet the requirements of micro/nano manipulation in some complex cases are the adequate workspace and payload capacity of the moving platform. This paper presents the development and control methodologies for a 2 degrees of freedom (DOF) flexure-based micro/nano positioning stage with the capabilities of decoupling motion and out-of-plane payload. The moving platform is horizontally supported by two orthogonal double parallel four-bar linkages, which are connected to the base through another four double parallel four-bar linkages. In order to improve the out-of-plane stiffness, four flexure links are utilized to vertical support the moving platform. Two voice coil motors are used for the actuation of the moving platform to obtain large working range. To investigate the static and dynamic characteristics, finite element analysis is preformed, the dynamic model of the positioning system is established, and the system identification is conducted using Adaptive Real-coded Genetic Algorithm (ARGA). In order to further improve the performance, the sliding model control with a PID type sliding surface technique is developed. A number of experimental testing has been conducted to validate the established models and the performance of the micro/nano positioning stage. It is noted that the developed stage has the capability of translational motion stroke of 2.13 mm and 2.02 mm in the X and Y axes, and the resolution is less than 250 nm. Further, it has excellent trajectory tracking and payload capabilities.