Design of ship course-keeping system via adaptive control techniques

Abstract

The paper discusses the problem of ship autopilot design based on the input-output feedback linearization method combined with the adaptive control techniques. At first, the nonlinear ship model of the Norrbin type is linearized with the use of simple system nonlinearity cancellation. Since the exact values of the model parameters are not known to overcome the resulting inaccuracies, these parameters are tuned in such a way as to guarantee the asymptotic stability of the system. Some novelty is that by treating the load disturbance as an additional, unknown parameter of the system, we do not need to introduce an extra integral action to deal with the appearing steady-state error. The simulations of the ship course change process confirmed the high efficiency of the proposed controller despite the assumed uncertainty of the system parameters and environmental disturbances. An important feature of this approach is also the elimination of the tuning problem.