Investigation into sliding-mode variable-structure control of a nonlinear ship-speed system

In this study, the ship-speed system was divided into the ship-screw subsystem and the main engine subsystem. According to the principle of ship propulsion, this study selected the ship speed, the rotation speed of the screw propeller and the rotation speed of the diesel engine as the stable variables and the fuel injection quantity of the diesel as the control input, so as to establish a nonlinear mathematical model of the ship-speed control system based on Newton's laws of mechanics. By considering environmental factors such as airflow, waves, and water flow as uncertain disturbances with known boundaries, the sliding-mode variable-structure controller of the differential equation can be solved by a type of affine nonlinear method. Finally, the simulation was run for two situations using the MATLAB platform: increasing the upper boundary of the uncertain disturbances and changing the fixed system parameters. The simulation results showed the strong robustness and favorable anti-interference capability of the sliding-mode variable-structure control of a nonlinear ship-speed system.