Cross-coupling effect and motion control of an autonomous underwater vehicle with internal actuators

Abstract

Hybrid autonomous underwater vehicles (AUVs) use internal actuators, e.g., tunnel thruster, moving mass, and ballast chamber, for yaw and pitch steering. Unlike control surfaces, internal actuators perform independently of relative flows around AUVs, thus suitable for missions which require excellent low-speed maneuverability. This research focuses on an investigation into the control design of an REMUS AUV using internal actuators to steer its heading direction. It has been shown that an internal moving mass together with a tunnel thruster is capable of providing actuations to serve the purpose. However, our analysis indicates that a coupling between roll and pitch motion causes the internal actuators to oscillate if depth-plane motion is neglected when deriving control laws for the internal actuators. We present a novel control strategy by taking advantage of the cross-coupling effect when designing the heading autopilot system with internal actuators. The effectiveness and robustness of the proposed design are validated by simulation results.