Efficient prediction method for the water-exit characteristics of unmanned aerial–underwater vehicles

Abstract

In the design of unmanned aerial–underwater vehicles (UAUVs), the performance during the transition from water to air is a crucial aspect requiring considerable attention. During water exit, UAUVs transition from water to air, crossing two vastly different mediums. Even after emerging from the water, the vehicle is still subjected to the forces exerted by the attached water. These challenges pose significant difficulties in predicting the water-exit performance. This study investigated a UAUV equipped with foldable wings and introduced a novel method for forecasting its water exit and flight characteristics using relay calculations. The method considered the complex force changes when crossing the water–air interface, as well as the force changes caused by wing unfolding and the influence of water attached to the vehicle after exiting the water. Additionally, an efficient aerodynamic coefficient identification method was adopted, and a novel approach for capturing and describing the state of the attached water was introduced. The accuracy and efficiency of the proposed method were demonstrated through comparisons with computational fluid dynamics methods. This method can be applied to the rapid iterative design of new UAUVs and provides a foundation for investigating water-exit motion control.