Nonlinear Sliding Mode Variable Structure (SMVS) Control of the Speed of a Ship with a Controllable Pitch Propeller (CPP)

Abstract

Based on the working principle of a ship with a controllable pitch propeller (CPP), a mathematical model of the ship-propeller subsystem, the engine-propeller subsystem, and the ship main engine subsystem was established. The model was represented by a set of differential equations, in which the ship speed, the rotational speed of the propeller, and the rotational speed of the main engine were used as the state variables, and the angle of pitch and the fuel injection quantity were used as the control input. The equation set was a multi-input nonlinear speed control system with the characteristics of coupling and nonlinearity. In order to design a sliding mode variable structure (SMVS) controller, appropriate coordinates were selected for the nonlinear state transformation, and the multi-input nonlinear system was decomposed into two single-input systems to solve the equivalent control through the manifold calculation. MATLAB simulation results showed that under the control of the angle of pitch and the fuel injection quantity, the ship speed, the rotational speed of the propeller, and the rotational speed of the main engine could quickly approach the given values, verifying the advantages of the SMVS control for complex multi-input nonlinear systems.