Active pendulation control of hoisting systems of ship-mounted cranes under ocean wave excitations: Principle and experimental study

Large-scale ship-mounted cranes are important facilities for marine construction. However, under harsh sea conditions, the hoisting system of a ship-mounted crane is often subjected to wave loadings, leading to frequent occurrences of large-amplitude resonance. This paper proposes an active control method, termed the active displacement compensation (ADC) approach, designed for suppressing the large-amplitude pendulation of the hoisting system of ship-mounted cranes. By controlling the position of the suspension point of the hoisting system using linear-motion actuators, the input excitations of the hoisting system induced by the ship motions can be partially or fully compensated in real-time. Therefore, the proposed ADC approach can significantly suppress the large-amplitude pendulation of the hoisting system. The optimal feedback gain and time delay of the ADC approach are theoretically obtained. The ADC approach has been validated by using a six-degree-of-freedoms shaking table test and numerical simulation on the in-plane pendulation suppression of a small-scale hoisting system. Experimental results indicate that the ADC approach achieves a pendulation reduction ratio between 85 % and 89 % for the hoisting system subjected to scaled ship motion records. This study may help develop efficient active control techniques for hoisting systems of ship-mounted cranes under harsh sea conditions.