Elasticdynamic Modeling And Analysis Of The 3-PRS Parallel Machine

The rigidty and dynamic characteristics of a newly patented 3-DOF PKM module named 3-PRS parallel manipulator,which is designed for high-speed machining of large aluminum-alloy structures in aerospace industry,and then provide a theoretical basis for improving the machining precision and processing efficiency of the machine.In view of this,a general framework--structural design for 3-PRS parallel manipulator before analysis in this paper,which the stiffness and dynamic characteristics of the mechanism are established.The main content of this dissertation are listed as followings:Firstly,The kinematic model of the mechanism is established by using the closed-loop vector method,and the kinematic model is used to analyze the position and the workspace analysis.which aims to clarify the kinematic chain scale and the motion limit range of the parallel power head,so as to provide the parameter basis for the prototype structure design.Secondly,the 3-PRS parallel mechanism components are designed to eventually form a 3-PRS parallel manipulator assembly model.In this paper,the finite element software ANSYS Workbench is used to analyze the key components of the 3-PRS parallel mechanism virtual prototype.It aims to obtain the design parameters of joint stiffness and further capture the weak link of the prototype design,and provide the optimal design theory for the components and assembly design of 3-PRS parallel mechanism.Thirdly,Based on the principle of deformation superposition and the idea of dynamic substructure,the dynamic model of 3-PRS parallel manipulator is established by counting the elastic deformation of moving hinges and branches.Which provides a theoretical basis for the study of system static/dynamic global forecast and performance optimization design.Fourthly,according to the built-in elasticity model and the joint reaction force /anti-moment equation,the global dynamic forecast and performance optimization design method of static characteristics are deeply studied.The internal mechanism of the pose angle,the mechanism scale parameter and the joint stiffness parameters of the stationary platform are analyzed.Finally,The rapid prediction and dynamic optimization of the natural frequency ofthe 3-PRS parallel manipulator system are studied.The low-order natural frequencies of the mechanism are analyzed by using the pose angle,the radius of the static and dynamic platform and the size of the branch cross-And the internal design of the relationship between the design parameters.The proposed general frame combines the advantages of FEM and anlytical methods,which has satisfying computation accuracy and efficency.The propsed mode can be extended to other types of PMs with minior revisions.The research conduted in the paper is of great use in geometric optimization,vibration reduction for a kind of PMs with lower mobility.