Adaptive Asymptotic Tracking Control for Underactuated Autonomous Underwater Vehicles With State Constraints

Due to energy constraint and reliability consideration, autonomous underwater vehicles (AUVs) have fewer independent actuators than their degrees of freedom (DOFs). Additionally, the position and velocity of AUV are sometimes limited due to physical constraints. The current solutions, such as Barrier Lyapunov Function (BLF) and Nonlinear State Dependent Function (NSDF), depend on the upper bounds of virtual controllers and dynamic surface control (DSC) technique. This paper develops a new trajectory tracking controller for underactuated AUV systems with state constraints. A quasi-linear relationship is established between the independent and dependent variables of the transformation function. The Nussbaum functions are employed to address algebraic loop problem, which avoids using the DSC and any approximator. Moreover, an auxiliary controller is introduced to deal with underactuation problem. The Lyapunov theory proves that the proposed controller can guarantee asymptotic tracking of desired trajectory while keeping the position and velocity of the AUV within their constrained bounds. The method can be extended to the $n$ th-order parametric-strict-feedback nonlinear systems. Finally, both simulation and experimental results reveal that tracking performance can be guaranteed by the proposed control scheme.