Rigid-Flexible Coupling Dynamics Research Of 3-DOF 3-RPS Parallel Robots

The 3-DOF parallel robots are very common in parallel robots,it is one of less degree of freedom parallel robots.They possess the parallel robots' characteristic like good dynamic performance,large structural stiffness,small movement inertia,high kinematic accuracy and strong carrying capacity and less degree f reedom robots' characteristic like simple structure,economical efficiency and easy control in the same time.Therefore,3-DOF parallel robots are widely used in the occasion which require for high speed,high movement precision,high stiffness and good dy namic characteristics,and has great research value and bright application prospects in these fields.The researches of 3-DOF parallel robots mainly focus on the fields like control,dynamics,kinematics and institutional knowledge and so on.Most of the r esearches on the dynamics of parallel robots only concentrate on the dynamic analysis of the rigid body members.In the process of study,all the components do not undergo any elastic deformation during the motion because they are regarded as rigid bodies.Therefore,the sole analysis of the rigid body dynamics of the parallel robots cannot truly reflect the coupling relationship due to the elastic deformation between the rigid body and the flexible body during the movement,also cannot truly reflect the ef fect on the motion accuracy of the end of the parallel robots made by deformation of the flexible body and the Mechanical Properties of the component.The researches on flexible parallel robots will become a whole new field of human research on robots with the higher and higher requirement for accuracy and efficiency of robots in the practical work.So the researches on this aspect will have very important practical significance and theoretical value.This paper regards 3-DOF 3-RPS parallel robots contain flexible components as the research object of this topic,comprehensively study the problems of this kind of robots in dynamic modeling,creation of flexible body and the rigid-flexible coupling dynamics simulation.Detailed research contents are as follows :Firstly,establishing the rigid-flexible coupling dynamics model for 3-DOF 3-RPS parallel robots contain flexible bar.There are several methods to establish the kinetic model,such as Newton-Euler,Lagrange equation and Kane equation.The Kane equation method is suitable for rigid body modeling and also appropriate for flexible body modeling,besides,calculation is relatively simple.So,using Kane equation method to establish the kinetic model of the 3-DOF parallel robots and deduce the equation of rigid-flexible coupling dynamics.Secondly,creating flexible bodies to 3-DOF 3-RPS parallel robots' the upper and lower connecting rod of the three branched chains.then transform robot flexible body needed parts into ANSYS finite element software,by selec ting the unit type,defining the unit real constant,selecting material properties,creating nodes,meshing,creating rigid area and generating MNF format of neutral files and other steps to complete the flexible connecting rod to create.Furthermore,in order to analyze the rigid-flexible coupling simulation of 3-DOF 3-RPS parallel robots by ADAMS software.Respectively,carrying out the dynamic simulation of rigid body model and rigid-flexible coupling model,then analyze the simulation results under these two models,such as,displacement,velocity,acceleration of the robots' mobile platform center of mass and joint force and moment.Finally,the simulation results of rigid body model and rigid-flexible coupling model are compared,and their displacement,velocity and acceleration deviation and the variation of force and moment are analyzed.The results show that the elastic deformation of the robot has some influences on the displacement accuracy of the rotor in the z-axis and the force of the flexible rod on the y-axis.The simulation of the rigid-flexible coupling dynamics of the robot can correctly and intuitively reflect the real work of the 3-RPS parallel robot,and it is concluded that the effect of the flexible rod deformation on the precision of the moving motion of the parallel robot is present,and provide a reliable theoretical basis to coupled dynamics researches.