Error scaling-based adaptive region tracking control for autonomous underwater vehicles

This article investigates the region tracking control problem for an autonomous underwater vehicle subject to external disturbances, model uncertainty, and large initial deviation. In the existing region tracking control schemes, the control signals have a serious chattering phenomenon when autonomous underwater vehicle's initial deviation is relatively large and the region tracking performance is only investigated from the position information. This article proposes an improved adaptive region tracking control scheme for autonomous underwater vehicle based on error scaling. Specifically, in the improved control scheme, the initial tracking error is artificially reduced by introducing an improved nonlinear mapping function to avoid the singular phenomenon and reduce the violent chattering phenomenon. In addition, the velocity error boundary is amplified by introducing the piecewise Lyapunov function to avoid the overadjustment of adaptive parameters in the developed controller. Meanwhile, it also reduces the frequent switching of control signals in the traditional control scheme which is caused by the pursuit of high-velocity precision. The region tracking performance is analyzed based on Lyapunov theory. Finally, the improved control scheme is applied to an autonomous underwater vehicle for simulation verification, and the comparison results demonstrate the effectiveness of the improved control scheme.