Fuzzy second-order integral terminal adaptive sliding mode control for marine cable-driven parallel grinding robot

During shipbuilding and maintenance, manual grinding is not only inefficient and highly risky in high-altitude operations, but also poses a threat to workers' lives due to the inhalation of metal dust. Consequently, this paper proposes a marine cable-driven parallel grinding robot (CDPGR). Firstly, a dynamic model of the CDPGR, incorporating ship motion, is established using the Lagrange method. The cable tensions are applied in the ADAMS virtual prototype to obtain the friction force and torque. Secondly, the CDPGR is highly sensitive to counter forces from the grinding mechanism, ship motion, impact loads, and other factors. Due to the insufficient control accuracy of existing controllers, a fuzzy second-order integral terminal adaptive sliding mode control (F-SOITASMC) is proposed based on the dynamic model. The stability of the control system is demonstrated using the Lyapunov theory. Furthermore, the effectiveness of the F-SOITASMC is validated through simulations under complex working conditions and compared with existing control strategies. Finally, the superiority of the F-SOITASMC is further confirmed via scaled-down prototype experiments. This study provides novel insights and methodologies for applying cable-driven parallel robots in marine environments.