Research On Dynamic Analysis And Active Control Of Planar Redundantly Actuated Parallel Robot

To meet the application requirement for parallel robot with high performance in the advanced manufacturing field,one kind of planar redundantly actuated parallel robot is taken as the main research object.The issues of rigid body dynamic modeling,performance analysis,rigid-flexible coupled dynamic modeling and active control are investigated systematically.The main contents are as follows.(1)The 3-RRR parallel robot and 4-RRR parallel robot are taken as analysis objects.Based on the closed-loop vector method,the inverse positions of two parallel robots are analyzed,and the inverse velocity Jacobian matrices and acceleration models of two parallel robots are further obtained.On this basis,the inverse kinematic simulation is performed.The kinematic performance of two parallel robots is compared based on the kinematic dexterity index.The results indicate that the redundant actuation can effectively overcome the Type II singularities with in workspace of parallel robot,and further improve its kinematic performance.(2)Based on the Kane formulation and multibody system dynamics theory,a modular modeling approach is proposed to establish the rigid dynamic models of above two parallel robots.The dynamic performance of two parallel robots are compared based a dynamic dexterity index defined from the rigid body dynamic model,and the inverse dynamic simulation is performed with respect to a specific trajectory.Finally,a virtual prototype model is developed to verify the theoretical model.(3)Aiming at high speed application and control requirement,the rigid-flexible coupled dynamic model of 4-RRR parallel robot is established.Firstly,the dynamic model of arbitrary branch is derived based on the assumed mode method and Kane formulation.Secondly,the rigid-flexible coupled dynamic model of system is established through integrating the dynamic equations of branches and moving platform and the constraint equations of system.On this basis,with the help of null space method,the generalized constraint forces are eliminated,and the simplified dynamic model of system in terms of independent coordinates is obtained.(4)To cater for active control,the dynamic model of permanent magnet synchronous servo motor(PMSM)is first established,and then the electromechanical coupled dynamic model of system is obtained by integrating the model of PMSM with the rigid-flexible coupled dynamic model of mechanical system.On this basis,the electromechanical coupled dynamic model of system is divided into two subsystems in different timescales,and then a hybrid controller is synthesized to realize trajectory tracking and vibration suppression.Finally,based on a specific trajectory of end-effector,the active control simulation is performed to verify the proposed active control approach.The outcomes of dissertation will enrich the research theory of parallel mechanisms,and have important theoretical significance and engineering value to the development of application field of parallel mechanisms.