A novel magnetorheological anti-swing system for offshore crane: System modeling and controller design

Constrained by the unique operational conditions and the swinging motion of the payload, offshore cranes exhibit low lifting efficiency and positioning accuracy during operation. In this paper, magnetorheological (MR) technology is applied in the realm of payload anti-swing and positioning of offshore cranes for the first time. The anti-swing system adopts a parallel mechanical configuration design, offering a simple structure that does not encroach upon the crane's working space and exhibits high levels of robustness. Based on the principle of robotics, the kinematic and dynamic model of anti-swing system is derived. Co-simulation analysis is conducted to assess the swing response of the crane's payload throughout the lifting and transfer process amidst irregular ocean waves. The findings demonstrate that the MR anti-swing system effectively mitigates payload swing, achieving an anti-swing effect of over 80%. With a similar anti-swing effect, the MR anti-swing system with time-varying current reduces energy consumption by 54% compared to the system with fixed current. Subsequently, experimental results from the physical prototype reveal that the anti-swing system can suppress payload swing by over 80% during cargo transfer processes. This underscores the capability of the MR anti-swing system to enhance payload transfer efficiency and positioning accuracy.