Roll dynamics and control enhancement of an oceanic AUV by a four-decoupled-fins system

Abstract

Autonomous Underwater Vehicles (AUVs) are subjected to several induced roll-destabilizing internal/external moments. Thus, roll control is a significant issue for many researchers, designers, and engineers to define, design, or perform the desired AUV missions due to the coupled dynamics of roll and other degrees of freedom (DOFs). In this paper, the roll dynamics and control enhancement of a REMUS AUV is studied using a four-decoupled-fins (FDF) roll control system by developing a 6DOF simulator. The results show that: 1) the roll angle deflections considerably affect the other degrees of freedom due to their coupled dynamics in both open-loop and closed-loop systems; 2) In large roll angle deflections, the FDF system (70% stern and 30% rudder fins) is needed to produce sufficient minimum oscillatory roll control forces. 3) The fins incident flow has lower energies in producing the roll control forces in lower forward speeds, causing the fluctuations of actuators' inputs and trajectory paths. 4) A limited but considerable desired roll angle can be achieved at a given forward speed; the maximum value of desired roll angle is 62∘ for the desired forward speed of 4m/s.