Design And Mechanism Analysis Of A New 4-DOF Parallel Mechanism

Parallel robot is an important branch of industrial robot in structure.With the rapid development of industrial automation and intelligence,parallel robots have been widely used in many fields such as industrial manufacturing,military industry,navigation and aviation,medical equipment and entertainment.According to the configuration characteristics of parallel robot,the research direction mainly focuses on mechanism,kinematics and dynamics.Compared with kinematics,the research on dynamics is less and not mature enough.Therefore,according to the mechanism theory,it is particularly important to put forward new parallel mechanisms and analyze kinematics and dynamics.Based on the 2-UPS+RPU mechanism,a new parallel mechanism configuration,2-UPS+(R+RPR)PU,is developed by adding a closed-loop topology.Compared with the mechanism prototype,the introduction of the new closed loop can make the mechanism have higher bearing capacity and driving force without affecting the freedom and motion ability of the original mechanism,and achieve greater speed and acceleration while decoupling the rotating pair,thus improving the comprehensive stability of the mechanism.In this thesis,the kinematics of the new mechanism is analyzed,and the inverse solution model of the mechanism position is obtained.The vector method is used to construct the closed-loop constraint equation,and the mapping between the expansion and contraction speed of the mechanism branch,the angular velocity and the generalized speed of the moving platform is deduced by deriving the closed-loop equation.By taking the partial derivative of the velocity mapping matrix,the acceleration mapping relationship between the branched chain and the moving platform is obtained.The workspace of the mechanism is obtained by constraining joint variables.The dynamic analysis of the new parallel mechanism is carried out.Firstly,based on the mapping matrix between the branch chain and the moving platform,the mapping between the center of mass of the swing rod,the center of mass of the telescopic rod and the speed of the moving platform in the branch chain is established respectively.According to the velocity and acceleration model,the dynamic model of the mechanism is established by virtual work principle,and the virtual prototype is established by ADAMS parametric modeling method to verify the correctness of the dynamic model.The physical prototype model is built and the simple motion control of the prototype is realized.