Research On Dynamic Positioning Control Method Of Safety Operation For Crane Vessels

As a kind of dynamic positioning ship, crane vessel plays a major role in the development and explotation of marine resource and marine engineering. During the lifting process, crane, cargo and ballast system will affect the parameters of the crane vessel; the platform will affect the control strategy; the marine environment will bring uncertain disturbance to the control system. To ensure the safety of the lifting operations, it is of great significance to design a robust and anti-disturbance dynamic positioning controller for crane vessel. Meanwhile, considering the collision avoidance between the crane 'vessel and the platform will also greatly improve personal and property safety.The "Offshore Oil 201" deepwater pipelaying crane vessel is studied in this paper. Firstly, the mathematical model which combines the characteristics of crane,cargo and ballast system is established. Secondly, we analysis the lifting operation's influence on the crane system, and we conclude that the crane, cargo and ballast system bring parametric uncertainties to the ship.This article designs a dynamic surface-active disturbances rejection controller(DSC-ADRC) for parametric uncertainties and unknown disturbances of the crane model. We design the DSC-ADRC controller by combining the dynamic surface algorithm and the active disturbances rejection control technology. Under the aforementioned controller, the crane vessel can achieve the target without overshoot,at the same time; the impact of the parametric uncertainties and unknown disturbances is deduced during the lifting operations. Simulation results show that the DSC-ADRC controller has greatly improved the accuracy and guaranteed the operation safety for the crane vessel.This paper puts forward a collision avoidance controller based on the improved artificial potential method for dynamic positioning of the crane vessel with heavy load.As the shape of the platform and the crane vessel will influence the process of collision avoidance, the crane is approximate to an oval, and the platform is approximate to a circle. Then, the nearest distance of the crane and the platform is derived by using the mathematical formula. Finally we realize collision avoidance by using the p times differentiable step function and the nearest distance of the crane and the platform to reconstruct the artificial repulsive potential function. Simulation results show that the crane achieves the goal without any collision and this algorithm protect the safety of the crane.