Research On The Structure And Design For Planar Three-DOF Compliant Micro-positioning Platform

In recent years, with the development of the semiconductor integrated technology, biological engineering, measurement science and technology, nano science and technology, the demands for precise positioning technology of system and equipment are increasing high. Based on the analysis of the key institution of the existing compliant micro positioning platform, a three DOF compliant micro positioning platform which uses different types of flexible motion and regard piezoelectric ceramics as driving device and has advantages of high stiffness, high resolution, low power consumption and small volume is designed.From the overall scheme design and the functions analysis of main parts, the thorough research on the planar three DOF compliant positioning platform is carried on from degree of freedom and motion output characteristics of the micro positioning platform, flexibility calculation of flexible motion, overall body stiffness analysis and prototype research. The concrete content of this article is as follows.Input and output characteristics of three commonly used compliant four bar mechanism which can achieve unidirectional translation are analyzed. The flexible hinge side incision contour and cross section shape of flexible moving pair influence output displacement of symmetrical four bar mechanism are discussed. Based on the above, a variable cross section soft symmetry four bar mechanism which is a highly efficient, low coupling straight line mechanism is put forward.On the basis of variable section smooth symmetric four bar mechanism,3-PRR compliant micro positioning platform is put forward which is more suitable for the piezoelectric ceramic drive with the current3-RRR platform comparison. The working principle and the main function characteristics of3-PRR compliant micro positioning platform are introduced. And micro positioning stage degrees of freedom of mechanism and the motor output properties is analyzed. Forward and inverse solution equations of the displacement magnification mechanism and3-PRR mechanism are obtained by using the pseudo rigid body model method and simplified method. Input and output displacement equation of the whole mechanism is obtained. And through its direct differentiation, the whole Jacobian matrix of the mechanism can be reached.The flexibility of calculation formula of variable cross section and four bar mechanism in the plane is obtained by using the card’s theorem. The relationship of flexibility coefficient of all direction and structure parameters of four bar mechanism is analyzed. The finite element model of the flexible four bar mechanism is built and is simulated by using of ANSYS. Through the contrast between the finite element analysis data and theoretical calculation, the derivation of the formula has higher calculation precision is showed. The whole stiffness matrix of the mechanism is built by the functional transformation principles and the relation between the output displacement and input force is obtained. Stiffness calculation model is correct is verified by the simulation of ANSYS. The reachable workspace of four bar mechanism under the condition of certain platform output angle is given. And the relation between the workspace area and output angle is analyzed.Based on the above analysis and research, the finite element model of the platform is established. Through the results of simulation by ANSYS, the simulation results and the calculation results are in good agreement and the calculation formula is correct are showed. Finally, the physical prototype is made on the basis of the study in theory and simulation.