| With the wide application of micro-nano technology in aerospace,nano-imprint lithography,precision machining,bio-engineering and other fields,each field has put forward higher technical requirements for positioning systems,not only to achieve nano-level positioning accuracy,but also to achieve large stroke cross-scale positioning.Piezoelectric ceramic actuators offer the benefits of high accuracy,high output force and small size,but the output displacement is too small and requires the use of a flexible amplification mechanism to increase the output displacement.It is of great theoretical and practical importance to study how to achieve cross-scale positioning with nanometer-level positioning accuracy.Two micro-positioning stages for precision operations have been designed to meet the requirements of micro-positioning stages for high accuracy and large strokes.The main research elements of this paper are as follows.1.The operating principle and functional parameters of the piezoelectric ceramic actuator are explained,and a preloading force application device for the piezoelectric actuator is designed.The device for applying the preload force is capable of applying the preload force in a safe manner.The intrinsic characteristics of the piezoelectric actuator,such as hysteresis,creep and non-linearity,are experimentally verified,providing a theoretical basis for micropositioning platform design and FEA.2.An innovative 2-DOF parallel micro-positioning platform was designed using a piezoelectric ceramic actuator as the drive element,a bridge amplification mechanism as the displacement amplification mechanism,and a composite parallel four-bar mechanism as the guide mechanism.The orthogonal design method is used for the optimisation of the structure of the bridge amplification mechanism,and the displacement amplification ratio and stiffness equations are derived.The stiffness,output displacement and inherent frequency of the 2-DOF micropositioning platform are designed and analysed,and the FEA of the displacement amplification ratio,maximum stress and inherent frequency of the micro-positioning platform is completed using ANSYS Workbench software.3.A 3-DOF micro-positioning platform was designed by a rational combination of a parametrically optimised bridge amplification mechanism and a half-bridge amplification mechanism,which added a degree of freedom for rotation around the Zaxis to the two translational degrees of freedom.The static characteristics of the platform were analysed and the 3-DOF micro-positioning platform was simulated by ANSYS Workbench software for output displacement,rotation angle,inter-axis coupling error,maximum stress and inherent frequency.4.Based on the theoretical analysis and FEA,a prototype of the 3-DOF micropositioning platform was machined by WEDM,and an experimental system was built to test the micro-positioning platform.The maximum output displacement of the platform in the X-direction is 86.52 μm,with a magnification of 4.36 and an inter-axis coupling error rate of 1.6%.The maximum output displacement in the Y-direction is 134.28 μm,with a magnification of 7.37 and an inter-axis coupling error rate of 1.9%.The maximum angular displacement of the output around the Z-axis is 0.25°.The results of the experiments show that the design of the micropositioning platform is practical and satisfies the expected requirements.The results of the experimental tests are compared with the results of the FEA,and the causes of the errors are analysed and appropriate improvements are proposed.The micro-positioning platform designed in this research topic adopts piezoelectric ceramics as the driving element,bridge amplification mechanism as the displacement amplification mechanism and distributed flexible mechanism as the guiding mechanism,which can achieve a large stroke while taking into account the positioning accuracy.The platform has a compact structure,fast response speed and good decoupling performance,which has broad application prospects and practical significance. |
