Energy-based Equipartition Wave Spectrum Method for Offshore Crane Control Under Varied Sea Conditions

This paper aims to acquire a more realistic roll angle sequence to further improve the control performance for offshore crane and similar equipment, while also striving to optimize wave simulation methods for marine engineering equipment. By combining classical wave spectra such as P-M (Pierson-Moscowitz) spectrum, ITTC (The International Towing Tank Conference) spectrum, and JONSWAP (Joint North Sea Wave Project) spectrum, along with the analysis of acquired parameters, a random wave slope sequence under specific sea conditions is generated using the energy equipartition method. Based on Conolly's linear roll theory, the relationship between wave slope and roll angle is derived, and the corresponding roll angle sequence is generated using the random wave slope sequence. The proposed approach can provide more realistic disturbance sequences for the simulation of control systems for ships, offshore cranes, or other ship auxiliary equipment, thereby optimizing control algorithms and achieving design objectives. Through simulation results of the offshore crane, the effectiveness of the proposed method was demonstrated by introducing the roll angle sequence.