Topology Design,kinematics And Stiffness Analysis And Optimization Of Novel 3-DOF Parallel Mechanisms

Two New 3-DOF parallel mechanisms with different topological structures are designed.Mechanism 1 is a 2-translational-1-rotational(2T1R)parallel mechanism with redundant branches,and mechanism 2 is a pure 3-translational(3T)parallel mechanism.The topological characteristics and kinematics of the two PMs are analyzed respectively,and the singularity and workspace of the two PMs are solved and analyzed,The stiffness performance of the mechanism is analyzed,verified and optimized.Firstly,according to the POC equation based topology design theory and method of parallel mechanism,combined with the working space superposition principle of SKC unit,based on the analysis and optimization of 2T planar mechanism and 3T spatial mechanism,the new three degree of freedom 2T1 R and 3T parallel mechanisms are designed;meanwhile,the main topological characteristics of the two new three degree of freedom parallel mechanisms are analyzed.Secondly,the kinematics models of two PMs are established,and the forward and inverse solutions of 2T1 R and 3T PMs are analyzed and verified respectively;the formulas of velocity and acceleration are derived,and the theoretical values of velocity and acceleration are obtained,which are verified by ADAMS software.Then,the singularity of 2T1 R and 3T PMs are analyzed,and their workspaces are solved.In order to solve the singular configuration of the 2T1 R PM,analyze its Jacobian matrix.At the same time,the reachable workspace of2T1 R PM is obtained by using MATLAB software.The Jacobian matrix of 3T PM is solved,the singularity of the mechanism is analyzed based on SKC unit,and the singular curve and singular surface of the mechanism are analyzed by using SIROPA package in Maple software.Furthermore,the workspace of the mechanism is analyzed based on SKC unit,and a cuboid task manipulator with excellent performance and no singularity is solved based on the principle of workspace Make space.Finally,the stiffness models of the two New 3-DOF parallel mechanisms are established based on the virtual spring method,and the stiffness matrix of the end of the branch chain is derived from the flexibility matrix.In MATLAB software,the torsional and linear stiffness performance and total stiffness of the two mechanisms in the task workspace are calculated.Import the 3D model into ANSYS software and compare the stiffness values to verify the correctness of the stiffness calculation.At the same time,the cross-sectional parameters of each member of the two parallel mechanisms are optimized by using the difference algorithm to reduce the material cost In the case of loss,the stiffness performance of the mechanism is optimized,so that the mechanism has greater bearing capacity.