Control Of Path Following And Dredging For The Trailing Suction Hopper Dredger

To guarantee sailing according desired trajectory, trajectory following control is required during dredging operations. In order to regulate the dredgers to a desired trajectory, a Dynamic Positioning control system is the key part. This paper relied on Innovation Joint Funding for industry-universities-institute of Jiangsu province and the study object of large trailing suction hopper dredger, focusing on the trajectory tracking control.Analyzing vessel dynamic specialty and the external disturbance characteristics of wind, wave and flow, reasonable assumptions is made for the model of vessel motion. The model simplicity based on both control demand and model complexity. By analyzing the rake arm stress varying during dredging operations, a mathematic model of the rake arm was proposed to estimate the drag force. All the researches above is made for TSHD( Trailing Suction Hopper Dredger) modeling and trajectory following control.Conventional LOS( line-of-sight) control strategy was augmented. An adaptive integral LOS control strategy was proposed by adding an adaptive observer. As the dominant factor, the current disturbance is estimated by an adaptive observer; the desired yaw is compensated by LOS strategy combined with the adaptive observer. So the trajectory tracking performance is improved. The conversion relation between controller variable and orientation variable is stated. The specific calculation methods were illustrated in which LOS control strategy was applied.The model parameters of trailing suction hopper dredger is varying according to different dredging operations and disturbance. Sliding mode control is employed to improve robustness and anti-interference ability of trajectory following controller. Simulation results showed that the sliding mode controller designed in this article can weaken "chattering" of control input under Dynamic Positioning system restrictions, achieving satisfied control quality. Moreover, the sliding mode control is superior to conventional PID control in comprehensive performance. An adaptive back-stepping sliding mode controller was proposed to overcome slowly varying disturbances. By this means, both adaptability and robustness of the controller were improved. At last, based on the adaptive integral LOS strategy and sliding mode controller, the simulation and trial experiment both showed that the trajectory following control is available out of practical engineering.