Motion analysis of an autonomous underwater vehicle tethered with an optical fiber for real-time surveillance

Autonomous underwater vehicles (AUVs) are playing an increasingly important role in ocean exploration. In some applications, an AUV can be tethered by a communication cable, such as an optical fiber, for real-time surveillance. This article focuses on the motion analysis of the AUV and cable coupling system to investigate the interaction between AUV and cable dynamic behaviors, especially under the current disturbance in the dynamic ocean environment. The dynamic equations of the coupled AUV and cable are derived using the well-known finite difference method and solved using the advanced trust-region method in MATLAB. The model-based simulation scheme is presented and further verified by comparing the simulation results with the validated ones published in the existing literature. The motion cases when the tethered vehicle maneuvers in a variety of motion modes and current scenarios are studied to conduct a systematic motion analysis. Both the variation in the cable tension at the towpoint and the configuration of the cable in the water are investigated. Based on the understanding of the cable and current effects on AUV motion, this article further explores the antitwining maneuvering strategy for the cable-tethered AUV moving in currents. The findings in this work can provide theoretical guidance for the safe operation of the AUV and cable coupling system in the field.