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A robust adaptive nonlinear control approach to ship straight-path tracking design

This article focuses on the straight-path tracking problem for underactuated ships with parametric uncertainties and completely unknown control gain coefficient under bounded exogenous disturbances. Combined Nussbaum gain technique with backstepping approach, an adaptive robust controller is developed such that all signals and states are globally uniformly ultimately bounded (GUUB). Consequently, an underactuated ship can be stabilized on a prescribed straight path in a GUUB manner under external disturbances induced by wave and wind. Numerical simulation results on an ocean-going training ship 'YULONG', belonging to Dalian Maritime University, are presented to validate the effectiveness of the proposed algorithm.