A Speed-Gradient Adaptive Control with State/Disturbance Observer for Autonomous Subaquatic Vehicles

In this paper the design of a nonlinear adaptive control system for fully actuated autonomous underwater vehicles in 6 degrees of freedom is presented. Both the positioning and kinematic tracking-problem are dealt with jointly in the adaptive approach. No knowledge about parameters of the vehicle dynamics and hydrodynamics is required beforehand for the design, except only for the thruster dynamics. The adaptation was carried out through a nonlinear speed-gradient adaptive control law. The dynamics of thrusters is considered in the design employing an inverse-dynamics technique and state/disturbance observation. The proof of the asymptotic convergence of the overall controlled system is shown. Selected numerical simulations depict the features of the proposed approach