Synchronization Control Of Parallel Robot With Redundant Actuation

Parallel manipulators have the following characteristics: stiffness, accuracy, speed and payload over their counterparts. However the singularity of the parallel mechanism affects the accuracy, stiffness, as well as sports performance. Parallel robots with actuation redundancy have attracted more and more attention of researchers these years, because they can improve the performance of parallel robots. However, their structure and the actuated way are very complicated, and the control of the mechanism is also complicated. Hence, it is very significant in theory and practice to study them.The subject of this thesis is planar 2-DOF parallel robot with actuation redundancy, and the aim is to analyze its dynamics and study its control method. The thesis will lay a scientific foundation for the control study of parallel robots of this type. The mathematic model of dynamics for the planar 2-DOF parallel robot with actuation redundancy is set up by Lagrange equation and Lagrange-D'Alembert's equation in this thesis, and the dynamics of the robot is analyzed. Three typical kinds of control methods: PD control, augmented PD control and computed-torque control are discussed, and the control block diagrams of these three algorithms are plotted. Augmented PD control and computed-torque control are applied to the planar 2-DOF parallel robot with actuation redundancy, based on which the dynamic simulation has been done.The parallel structure has characteristics with relatively small workspace and coupling relationship between joints, so a new control strategy which can be easily realized in engineering is proposed. The control strategy supposes the inertial matrix and the coriolis force terms are constant to cut down the total amount of computation. It restrains the model error and the coupling error between axises. The stability theory proposed by Lyapunov has proved the stability of the controllers. Moreover, simulations and experiments are carried out to compare coupling controller with PD controller, and the result verifies the above claims.