The Dynamic Modeling Of 2-DOF Redundant Actuation Parallel Robot Based On U-K Theory

The redundant actuation parallel robot has great advantages,such as high precision,great rigidity,heavy-load capacity and compact structure.Hence it has been widely used in the medical,aerospace,military and other sophisticated areas.As the complex multi-closed loop structure of the parallel robot,its dynamic modeling process is complex and complicated.At present,the dynamic model can be obtained by the traditional modeling methods,but there still exist some weaknesses in modeling process.For example,it needs auxiliary variables,hard to get the analytical dynamic model,and can not establish the dynamic model systematically when the constraint is non-ideal.For the above problems,the 2-DOF redundant actuation parallel robot was taken as the research object.A new modeling method of multi-body system,the cascading and clustering modeling method based on the Udwadia-Kalaba theory,was utilized to the dynamic model research of robot in this paper.First,the paper started with the kinematics analysis of the 2-DOF redundant actuation parallel robot.The forward and inverse solution of motion position was solved.And the relation of the velocity and acceleration between the joints and end effector of the parallel robot was created.Besides,the dynamic analytical model of the parallel robot was constructed by the cascading and clustering modeling method.Through the Lagrange multiplier method,the dynamic model developed by this new method was justified theoretically.And the dynamic model of the parallel robot was simulated by MATLAB.Finally,considering the reality that non-ideal constraint exists in the active joints of parallel robot,which may produce the friction force in the active joints.The analytical equation of the joint friction was formulated,and the joint friction was decoupled with constraint.Then the decoupled and analytical dynamic model of parallel robot was established which was simulated by MATLAB ultimately.The results indicated that the cascading and clustering modeling method is on the systematization,simplicity and availability of establishing analytical dynamic model of the 2-DOF redundant actuation parallel robot,which has lay the foundation for the robot dynamic control.