| With the development of science and technology,precision processing technology has become the important factors affecting the development of manufacturing industry,leading to higher requirement to the precision positioning technology,the traditional rigid the performance of parallel mechanism have been unable to meet the requirements of the current precision positioning technology,the mems,precision optical,aerospace,biomedical fields such as defects.The compliant mechanism has the advantages of free assembly,zero clearance,no friction and no lubrication,so it provides a new solution to solve the above problems.In this paper,based on the relevant theory of compliant mechanism and parallel mechanism,through the flexible branched chain replacement,on the basis of 4-URU flexible parallel mechanism,put forward a kind of four degrees of freedom for precision positioning platform centralized flexibility fully compliant parallel mechanism,on the basis of complete its configuration design,using the method of variable density on the topology optimization and reconstruction design,A new fully compliant parallel mechanism with distributed flexibility was developed,and the static and dynamic performances of the two configuration positioning platforms were calculated theoretically and analyzed by finite element simulation.The results show that the distributed compliance fully compliant parallel mechanism has better static and dynamic performance,higher stiffness,stability,vibration resistance and positioning accuracy.The specific research contents are as follows:（1）Based on the 4-URU type rigid parallel mechanism,a 4-Dof centralized flexibility fully compliant parallel mechanism was designed by using the flexible hinge substitution method and combining with the requirements of technology,and its stiffness was analyzed.Firstly,the motion characteristics of 4-URU rigid parallel mechanism are analyzed by using screw theory.On this basis,4-URU parallel mechanism is converted into 4-URU flexible parallel mechanism based on the prototype of 4-URU parallel mechanism and the design theory of high-precision compliant mechanism.Considering the technological requirements,a4-Dof centralized compliant parallel mechanism with integral chain structure was designed and applied to precise positioning platform transmission mechanism.By using the element motion equation,the total stiffness matrix of the branch chain was obtained through the transformation between the hinge and the branch chain coordinate,and then the overall stiffness of the positioning platform was obtained by the stiffness matrix of the branch chain in parallel.According to the virtual work principle,the deformation of the moving platform was solved.Finally,the effectiveness of the stiffness calculation results is verified by theoretical calculation and finite element simulation.（2）After the design and analysis of 4-URU centralized compliant fully compliant parallel mechanism was completed,a distributed compliant fully compliant parallel mechanism was developed for precise positioning platform by using SIMP variable density method and topology optimization and structural reconstruction design.In type 4-URU centralized flexibility fully compliant parallel mechanism based on the original configuration,based on SIMP variable density method,positioning platform mathematic optimization model and geometric model,the ANSYS topology optimization module,complete the optimization of the area and keep the locale,topology optimization iteration,and the optimization results are fitting refactoring,Complete the design of distributed compliant parallel precise positioning platform.The static stiffness analysis was carried out by finite element simulation software,and the simulation results were compared with the simulation results of the centralized compliant full-parallel precise positioning platform.The results show that the distributed compliant full-parallel precise positioning platform has higher stiffness and better bearing performance.（3）Using finite element analysis software,the positioning accuracy of three different configuration positioning platforms is analyzed.Platform based on screw theory to establish the positive solution of mathematical model,get the relationship between the input and output,then using the finite element software to complete three configurations statics analysis of positioning platform,applied at the end drive torque,the positioning platform can be obtained,respectively,the geometric center of moving platform positioning platform micro motion parameters,comparing the simulation result shows that the positioning accuracy of the distributed compliance fully compliant parallel precise positioning platform is higher,which can reach micron level or less.Its motion characteristics are similar to those of 4-URU parallel mechanism,and the errors are within a reasonable range.（4）The modal analysis of three configuration positioning platforms is completed by using finite element software.The flexible structure of the positioning platform is divided into elements and the dynamic equations of the positioning platform are constructed.The modal analysis of three different configuration positioning platforms designed in this paper is carried out by ANSYS software.By comparing the simulation results,it can be seen that the first 6 order natural frequencies of the fully compliant parallel precision positioning platform with distributed flexibility are improved to varying degrees,showing excellent anti-interference ability and anti-vibration performance,and better dynamic performance. |
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