Development of high precision positioning stages with multi-DOF and cross-scale output based on flexure hinges

Abstract

High precision motion stages have a wide range of applications in many modern industries, such as integrated circuit manufacturing, aerospace, ultra-precision machining, atomic force microscope technology and other cutting-edge fields. Among them, the flexible and high-precision motion stages driven by piezoelectric ceramics play a key role in nano lithography manufacturing equipment, high-precision micro technology equipment and high-precision machining equipment. In recent years, the rapid development of nano manufacturing technology challenges the design, modelling and motion control of high-precision motion stages. This thesis focuses on the core technical problems in high precision positioning technology, aiming at the development of precision motion stages driven by piezoelectric ceramics. Firstly, this thesis studies the driving characteristics of piezoelectric ceramics and analyzes the application advantages of piezoelectric ceramics in the field of high-precision motion. Meanwhile, the problems in the application process are also analyzed, such as the small output displacement of piezoelectric ceramics, the hysteresis effect in the process of contraction and elongation, etc. In view of these problems, this thesis summarizes the current research situation, analyzes the current research direction. Secondly, this thesis summarizes all kinds of compliant mechanical structures in the current research field, analyzes the mechanical characteristics of all kinds of flexure hinges, and explains two kinds of analysis methods of compliant mechanisms: pseudo rigid body method and stiffness matrix method. According to these methods, the kinematics and dynamics of the new high-precision motion stages can be analyzed. Then, a new constant force manipulator is designed and analyzed utilizing stiffness matrix method. The compact damage-avoiding gripper [CDAG] is consisted of compact two-stage amplifier module and constant force mechanism module. The effect of constant force structure module is realized by integrating the positive stiffness beam with the negative stiffness beam. The compact two-stage amplifier is composed of two classical bridge amplifiers in series so as to augment the ratio of amplification. In order to effectively restrain the hysteresis effect of piezoelectric ceramic, this thesis synthesizes the theory and method of high-precision motion control of piezoelectric ceramic actuator and proposes a novel control method to better solve this problem. The control method is a novel sliding mode control method which proposing a new reaching law based on the theory of sliding mode control which effectively reduces the buffeting amplitude and the width of quasi sliding mode domain to improve tracking accuracy. Finally, for solving the problem of the contradiction between the two main performance indexes of the high precision motion stages, which are large travel and high precision, this thesis studies the current domestic and foreign mainstream research results to solve this problem. Then, a new high precision ultra-compact decoupled XYZ0 motion stage based on flexure hinges is designed and analyzed. Compared with the existing stages, the proposed high precision motion stage has many advantages such as extremely compact structure, large output decoupling motion and XYZ0 four axes output displacement. Then, kinetostatic analysis of this new XYZ0 stage is conducted to analyze the stage. Finally, the finite-element analysis (FEA) and prototype experiments are implemented to verify the design objectives.