A novel 5-DOF high-precision compliant parallel mechanism for large-aperture grating tiling

Abstract

In combination with the advantages of parallel mechanisms and compliant mechanisms, a 5-DOF compliant parallel mechanism is designed to meet the requirements, such as large stroke, large load capacity, high precision and high stability, for a large-aperture grating tiling device. The structure and characteristics of the 5-DOF compliant parallel mechanism are presented. The kinematics of the mechanism are derived based on a pseudo-rigid-body model as well. To increase the tiling position retention stability of the mechanism, a closed-loop control system with capacitive position sensors, which are employed to provide feedback signals, is realized. A position and orientation monitoring algorithm and a single neuron adaptive full closed-loop control algorithm are proposed. Performance testing is implemented to verify the accuracy and the tiling position retention stability of the grating tiling device. The experimental results indicate that the tiling accuracy reaches 0.2ĝ€μrad per step and 20ĝ€nm per step, and the tiling position retention stability can achieve 1.2ĝ€μrad per 30ĝ€min and 35ĝ€nm per 30ĝ€min in the rotational direction and the translational direction, respectively.