Linear Active Disturbance Rejection Control for Course Keeping in Harbor

Due to the low speed and shallow water effect of the ship when sailing in harbor, the parameters of the ship model are changed, and the traditional PID autopilot cannot effectively control the ship's course. In this paper, the effects of changes in water depth and ship speed on the ship are transformed into changes in ship model parameters, and ship parameters are used as part of the controller design. Using linear active disturbance rejection control(LADRC) algorithm is applied to design the ship course controller. A linear extended state observer is used to track the states of the ship model in real time and extract the differential state variables of the ship model. Integrates external disturbances such as wind and waves and internal disturbances of the ship into total disturbances, which are controlled by PD control law. Based on the Nomoto model, this paper adds disturbances such as wind and waves to simulate the real ship's navigation environment, and simulates the ship's course keeping control under the disturbance of wind and waves in difference speed. It can be seen from the simulation curve that there is no overshoot of the course control, and the ship's course can still be effectively controlled when facing the speed changes and interference from wind and waves.