Dynamics analysis and active control of a floating crane

Original scientific paperThe floating cranes, which transfer payloads during offshore constructions, need meet rigorous demands for efficiency and safety in serious sea conditions while the unexpected motion of the floating crane caused by wave make it even harder.This paper analyses the dynamics of a floating crane and presents an active heave compensation system (HCS) to allow the payloads motion decoupled from the wave-induced ship motion in the vertical direction.Specifically, virtual prototyping technology is introduced for the floating crane systems to investigate the real behaviour of the HCS.A virtual mechanical model of the floating crane is created to analyse the dynamics of the floating crane.In addition, an active HCS is designed for the under actuated floating crane system.A self-adaptive PID control law based on improved genetic algorithm is proposed for the essential part of the HCS.The co-simulation and experiment results demonstrate that the payload motion due to the ship's vertical motion can be reduced significantly in harsh sea conditions.