Abstract:

Aiming at the trajectory tracking of a hydraulic parallel filling robot which contains model uncertainties and larger external disturbances, a dynamic decoupling backstepping robust control strategy based on a joint finite time disturbance observer (FTDO) is proposed. Firstly, the parallel manipulator is treated as a set of joint subsystems with external disturbances, and then two FTDOs are synthesized for each actuator to realize the accurate estimations of both the matched and unmatched uncertainties. Meanwhile, based on the system decoupled dynamic model in the joint space, a backstepping robust controller is synthesized to stabilize the closed-loop system. Finally, the boundedness of all the signals in the closed-loop system and the finite-time asymptotic convergence of the joint tracking errors are verified theoretically via the Lyapunov method. The experiment results show that the proposed controller has excellent trajectory tracking performance and strong joint anti-disturbance ability under different work conditions, which can meet the application requirements in the practical filling task.

Key words: Parallel filling robot, Finite-time disturbance observer, Dynamic decoupling control