A heave compensation approach for offshore cranes

Offshore installations during harsh sea conditions results in rigorous requirements in terms of safety and efficiency for the involved crane system. Hence a heave compensation system based on heave motion prediction and an inversion based control strategy is proposed. The control objective is to let the rope suspended payload track a desired reference trajectory in an earth fixed frame without being influenced by the heave motion of the ship or vessel. Therefor a combination of a trajectory tracking disturbance decoupling controller and a prediction algorithm is presented and evaluated with simulation and measurement results.