Performance Research And Optimization Design Of The Parallel Mechanism Based On Flexure Hinges

Recently, the requirement of high precision pose adjusting devices is becoming more and more urgent. With the rapid development of parallel technique and micro-displacement technique, high precision pose adjusting parallel mechanisms has become an important realm on high precision pose adjusting. In immersion lithography equipment, a kind of micron 3-DOF high precision pose adjusting device is required to adjust the pose of immersion unit. This paper including four parts is focused on this kind of high precision pose adjusting device based on parallel mechanism and flexure hinge.1) Kinematics model of the 3-PSR-V parallel mechanism was built and the detailed derivation process was given in this paper. Particularly, an inverse kinematics solution method when z,γ,β was given was proposed. This method could be used to solve problems for the control in some special measurement mode. The correctness of the kinematics model was verified by simulation.2) Based on the pseudo-rigid-body model, the stiffness model and precision model of right circular flexure hinge were built. Evaluation standards of flexure hinge and corresponding mathematical model were proposed. Furthermore, a parallel flexure hinge structure with revolute joint function and corresponding stiffness model were built, which obviously enhanced the vertical stiffness and torsion stiffness. The correctness of the flexure hinge stiffness model was verified by simulation.3) In terms of application, optimization design on right circular flexure hinge, parallel flexure hinge and some other kinematic pairs in the parallel mechanism were carried out. Besides, some key dimensions of parallel mechanism based on flexure hinges (PMboFH) were optimized. The tests of moving platform and PMboFH showed that the PMboFH in this paper was born with excellent stiffness and dynamic performance.4) Post-processing of PMboFH was also explored. Based on the error analysis, the error model of PMboFH was established by vector method. The design of parameter identification tactics gave an access to transfer the multi-objective optimization into single-objective optimization. Particle swarm optimization with variation was proposed, by which the parameters of PMboFH was identified. Precision performance tests showed the open loop re-orientation accuracy (z, α,β) of PMboFH reached the standard of -0.5-1.0um,±0.01rad and±0.03mrad respectively, which indicated that the PMboFH in this paper is a micron precision pose adjusting parallel mechanism and it meets the requirement of pose adjustment in immersion lithography equipment.