Second-Order Sliding-Mode based Synchronization Control of Cable-Driven Parallel Robots

Cable-driven parallel robots (CDPRs) can provide a high speed and a heavy payload in a large workspace. The main challenge of the CDPRs stems from the dynamic control, in which all the cables must coordinate with each other to remain in tension, and the cable-driven form may lead to model uncertainties. To solve it, the second-order sliding mode (SOSM) is combined with the multicable synchronization idea to propose a new SOSM-based synchronization control (SOSM-SC) strategy for the CDPRs. The goal of the cross-coupled control approach is to improve the synchronization motion relationship between all the cables and guarantee better trajectory tracking control, whereas the SOSM can restrain the model uncertainties and external disturbances. The Lyapunov theory is utilized to prove the asymptotic stability of the closed-loop control system of CDPRs. Trajectory tracking experiments indicate that compared with the existing synchronization control strategy and the augmented proportional-derivative strategy, the proposed SOSM-SC strategy significantly reduces the cable tracking error and the cable synchronization error, and ultimately improves the control accuracy for the mobile platform. The tracking experiments of the antidisturbance indicate that the SOSM-SC strategy can retain good tracking accuracy under external disturbances.