Design of Ship Course Controller Based on Improved Adaptive Backstepping

This paper presents an improved adaptive backstepping control method based on uncertain parameters of ship model to design the ship course controller. The K-class function is introduced into every step of the virtual function design to ensure the stability of the closed-loop system and accelerate the convergence speed of the system state variables. Simulation results show that IAB control method is more superior than the traditional adaptive backstepping control method. Introduction Course control is the key of ship movement. Aiming at the problem of ship heading control strategy, many scholars have done a lot of researches in this field. The design of autopilot based on PD and PID is simple and effective, but its effect is not ideal in the real environment [1]. In [2], a ship autopilot is designed by combining high-order sliding mode control with dynamical sliding mode control. In [3], the approximation of unknown and uncertain dynamics is achieved by T-S fuzzy system, which guarantees the boundedness of all the signals in the closed-loop system. In [4], an adaptive control algorithm based on Nussbaum gain is proposed for the course keeping system, which solves the uncertainty of the ship course keeping system and reduces the influence of external interference and simplifies the control law. The backstepping method has advantages especially in nonlinear problems and has attracted extensive attention in ship motion control. In [5], an improved brief backstepping controller that replaces heading errors with a nonlinear function is proposed, which has proven to be robust. In [6], an eigenvalue decomposition adaptive sliding mode controller (SMC) is proposed, which can effectively eliminate the steady-state error and improve the capability of ship course keeping. In [7], an advanced adaptive observer based ship dynamic positioning backstepping is proposed, and the bias term is used to represent slow-varying disturbances and unmodeled dynamic. In [8], the backstepping is proposed to design station-keeping controllers of unmanned surface vehicle, and favorable results are obtained in the actual marine control system. In [9], the backstepping method is also adopted to design controller for under-actuated ships with input saturation, achieving global stability tracking. This paper takes the model parameters in the ship heading control system will be affected by the environment into account, which results in uncertainty of the model parameters. A new ship course controller is designed by combining the K-class function and the adaptive backstepping method to accelerate the system convergence speed and accurately track the desired course. Finally, the simulation results show that the proposed method has better performance. Problem Descriptions The Norrbin nonlinear model is used to describe the relationship between ship’s rudder angle ( )  and the rate ( ) r of the course ( )  , which is as follows: International Conference on Modeling, Analysis, Simulation Technologies and Applications (MASTA 2019) Copyright © 2019, the Authors. Published by Atlantis Press. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/). Advances in Intelligent Systems Research, volume 168