Ship course control system with compensation of external disturbance on steering gear

Abstract

The article focuses on developing synthesis methods for automatic heading control systems for the rudder-controlled sea vessel. The solution of the problem of vessel heading control is carried out in the conditions of heavy sea. The disturbing effect of the external water environment causes the vessel yawning, which results in exceeding activity of the steering gear. This leads to its increased wear and loss in the longitudinal speed of the vessel. To reduce the wave effect there has been supposed an approach based on the additionally introduced internal model of the ship dynamics. The given approach is aimed at improving the operation of the steering gear in rough seas. To implement the proposed algorithm, changes are made to the original system by introducing an internal model in parallel to the control object and modifying the feedback channel of the control system. To describe the sea vessel dynamics there is used the 1st order Nomoto model, the steering gear model is implemented in accordance with the imposed speed limits and the rudder shift value. Wave disturbance is close to harmonic disturbance. The identification of the parameters of the internal model can be carried out in advance, both by maneuvering tests and by the process of operation. Numerical simulations carried out in the MATLAB/Simulink system confirmed the advantage of the proposed approach. The synthesis of control in a system with an internal model makes it possible to significantly neutralize the influence of wave disturbance. The modifications introduced to the original control system help to improve functioning of the steering gear, significantly reducing the number of rudder shifts during operation.