Kinematic and Dynamic Analysis of a 4DOF Parallel Robot with Flexible Links

The paper deals with the dynamic behaviour of a 4DOF parallel robot with decoupled motions, three orthogonal translations and one rotation, in a comparative approach of flexible versus rigid links, and also the influence of friction in the four active prismatic joints. The ADAMS software and its AUTOFLEX module were used to model the parallel robot and further to identify the end-effector motion errors on a representative trajectory, due to the natural flexibility of the robot links, and the variation of the actuating forces needed in the input joints with both links flexibility and active joints friction. The obtained numerical results show significant resultant errors of the end-effector from the planned trajectory, generated by link elastic deformations, and important errors of actuating forces (up to 300 %) in the assumption of both link flexibility and active joint friction. The results are useful for robot designers to optimally select the actuators and appropriate design the control system to ensure trajectory high accuracy on the robot workspace.