Abstract

Path following for underwater vehicles remains a significant challenge due to underactuation in the sway and heave directions. Most existing approaches rely on line-of-sight guidance to address this issue. In this paper, we explore an alternative approach using kinematic guidance, based on virtual reference point guidance, wherein a fictitious point offset from the vehicle's center of rotation is used to reformulate the kinematic control problem and mitigate underactuation constraints. While this concept has been explored to some extent, previous works have largely overlooked the impact of the vehicle’s attitude. To address this limitation, we propose a solution that simultaneously accounts for the vehicle’s attitude while minimizing cross-track error by defining the error dynamics in the body reference frame, which enables direct control of yaw and sway through yaw rate actuation. A model predictive controller is designed to optimize both attitude stabilization and trajectory tracking performance and is enhanced with an adaptive extended Kalman filter-like observer to estimate the sideslip caused by ocean currents and external disturbances. The proposed controller is evaluated under the influence of ocean currents and modeling uncertainties, and compared to an existing method from the literature, demonstrating its effectiveness in maintaining path-following accuracy while stabilizing the attitude.