3-UPU Parallel Mechanism Dynamics Study

In comparison with series mechanism,the advantages of parallel mechanism,such as strong bearing capacity,good dynamic performance,large rigidity,high motion accuracy and easy feedback control,have received great attention,which has been attracting significant interest of scholars at home and abroad in the past years.The study of dynamics is one of important part of parallel mechanism,focusing on kinematic analysis,calculation of inertia force / inertia moment,force analysis of each member,establishment of dynamic model and analysis of its conclusions.In parallel mechanism,the results of dynamics can be extensively applied to the selection of the driving elements,the selection of control strategies and the optimal design of the structure based on the dynamics.The dynamics model is the basis of the design and control of the parallel mechanism.This paper attempts to carry out the dynamics research based on the 3-UPU parallel mechanism.(1)The analysis of the kinematics of the 3-UPU parallel mechanism First,set up the coordinate system and get the position coordinates of each component.Second,the approach to obtain the positive solution and the inverse solution of the position of 3-UPU parallel mechanism is vector method.Last,a mapping relation,the solution of the input speed of the branched drive rod and the output speed of the moving platform from the certain method,approaches to handle the relationship between input and output acceleration.3D entity modeling is carried out through Pro/E software,which is then imported into ADAMS software.The last,verify the simulation by Matlab and ADAMS.(2)The analysis of the static analysis of 3-UPU parallel mechanism First,substitute the mapping relation obtained by the kinematic analysis of the mechanism in the static equilibrium equation established through the principle of virtual work.Second,taking the kinematic chain as the research object,solve the binding force on the joint hinge is solved by using dismantling rod method.Last,establish the virtual prototype of 3-UPU parallel mechanism in Adams software and simulate the static model of the mechanism;calculate the static equilibrium equation in Matlab software.(3)The analysis of the dynamic analysis of 3-UPU parallel mechanism Introduce the solution from the inertia force and moment of each component into the equation established by the virtual work principle,and then obtain the dynamic equation.Compute the binding force of the motion pair of the mechanism by using the method of dismantling rod and simulate by Matlab software and ADAMS.(4)The stiffness analysis of 3-UPU parallel mechanism Establish the stiffness mapping matrix of 3-UPU,define the stiffness performance evaluation index of parallel mechanism and evaluate.