Robust and adaptive path following for underactuated autonomous underwater vehicles

This paper proposes a nonlinear robust adaptive control strategy to force a six degrees of freedom underactuated underwater vehicle with only four actuators to follow a predefined path at a desired speed despite of the presence of environmental disturbances and vehicle´s unknown physical parameters. The proposed controller is designed using Lyapunov´s direct method, the popular backstepping and parameter projection techniques. The closed-loop path following error can be made arbitrarily small. Numerical simulations are provided to illustrate the effectiveness of the proposed methodology for the path following of underactuated underwater vehicles.