Fast Terminal Sliding Mode Control with Synchronization Error for a 6-DOF Cable-driven Parallel Robot

Because of the structural characteristics of the cable-driven form, the control of cable-driven parallel robots is always faced with the constraint that the cable tension must be kept positive and the challenge of model uncertainties. In order to solve these problems, a novel fast terminal sliding mode control with synchronization error (FTSMC-SE) is proposed by combining the synchronization motion between cables and the fast terminal sliding mode. For one thing, through coordinating the motion of adjacent cables, the cable slack is effectively restrained, that is cable tension remains positive. For another thing, by taking advantage of the finite-time convergence property of the fast terminal sliding mode, the trajectory tracking accuracy is improved owing to the faster error convergence. The trajectory tracking simulations and experiments are implemented on a 6-DOF parallel robot driven by 8 cables. Compared with the augmented PD control strategy and the synchronization control strategy, the proposed control strategy can significantly ensure the synchronization motion of all cables, converge the errors at a faster speed, and eventually achieve better control performance during the trajectory tracking tasks. © 2022 Editorial Office of Chinese Journal of Mechanical Engineering. All rights reserved.