From Aerial to underwater: Modeling and trajectory tracking control of the underactuated quadrotor hybrid Aerial underwater vehicle

Abstract

The underactuated Quadrotor Hybrid Aerial Underwater Vehicle (HAUV) can operate in multiple mediums and seamlessly transition between them. Affected by the buoyancy, underwater control suffers a critical 180° turnover singular problem. To address this challenge, this paper presents a detailed underwater 6-degree of freedom dynamics based on the unit quaternions. A novel geometric attitude extraction method is introduced to improve the classical geometric control. Subsequently, a cascaded controller is developed for trajectory tracking. This controller consists of a position loop and an attitude loop, integrated through the attitude extraction method. It extracts the desired attitude for the inner loop from the desired thrust direction in the outer loop. Rigorous analysis demonstrates that the closed system exhibits global asymptotic stability, effectively mitigating the singular problem. Simulations demonstrate that the controller effectively adapts the quadrotor HAUV, regardless of its buoyancy (positive, negative, or neutral), to accurately track underwater trajectories and fixed points.