Session: 04-06-01 Underwater Vehicles & Subsea Communications I

Submission Number: 181804

A Single-Drive Tether Tensioning Mechanism for ROV Deployment from Unmanned Surface Vehicles 

Unmanned surface vehicles (USVs) have become increasingly important platforms for marine research, resource exploration, and environmental monitoring. Operating autonomously or under remote supervision, USVs exhibit superior maneuverability compared with conventional vessels and are well suited for missions conducted over wide marine areas or in hazardous environments. They are particularly valuable for tasks such as mine countermeasure operations, coastal mapping, and oceanographic data acquisition, where human presence is either impractical or unsafe. Furthermore, USVs can serve as mobile platforms for launching and recovering remotely operated vehicles (ROVs), enabling real-time underwater observation, sampling, and inspection for scientific and engineering purposes.

Despite their versatility, one of the persistent challenges in USV–ROV combined operations lies in the management of cable tension during ROV deployment and retrieval. Variations in vessel motion, sea state, or ROV movement can cause cable slack or excessive tension, leading to potential issues such as cable entanglement, overloading, or even mechanical failure. Conventional tension control systems often rely on multiple actuators or sensors, which increase system complexity, energy consumption, and maintenance demands.

To address this issue, this study proposes a novel ROV cable tensioner that achieves continuous and stable tension regulation using only a single power source. The key innovation of this mechanism is its ability to perform cable reel-in, pay-out, and automatic tension control simultaneously without requiring multiple drive systems or feedback components. The proposed design consists of three principal elements: a cable driving roller, a pressure roller, and a unidirectional ratchet. During the cable retrieval phase, the cable passes between the driving and pressure rollers before being spooled. The pressure roller, preloaded with compression springs, applies a controlled normal force that maintains appropriate pre-tension, ensuring smooth and even winding onto the reel. During the cable pay-out phase, the unidirectional ratchet engages the driving roller, transmitting torque in a single direction to generate frictional resistance. This friction provides the necessary pulling force to preserve consistent cable tension as the cable is released. By integrating both reel-in and pay-out control functions under one drive system, the proposed design eliminates the need for additional powered rollers or electronic feedback mechanisms. This simplification not only reduces the system’s weight, cost, and energy consumption but also enhances operational reliability—an important consideration for compact USV platforms with limited onboard resources.

Based on this conceptual framework, the mechanical design of the ROV cable tensioner was finalized, and a prototype spool assembly was fabricated for preliminary functional testing. Initial results demonstrate that the single-power-source mechanism effectively maintains steady cable tension in both operational modes, validating the feasibility of the proposed approach. This innovation provides a promising solution for small- and medium-scale USV–ROV systems, where simplicity, reliability, and compactness are critical for efficient and safe underwater operations.

Presenting Author: Hsin-Hung Chen Institute of Undersea Technology, National Sun Yat-sen University

Presenting Author Biography: Dr. Hsin-Hung Chen received his B.S., M.S., and Ph.D. degrees in Mechanical Engineering from National Cheng Kung University, Tainan, Taiwan, in 1991, 1993, and 1996, respectively. Following a brief period as a shipbuilding research officer with the R.O.C. Navy to fulfill his mandatory military service, he joined the Institute of Undersea Technology at National Sun Yat-sen University in 1998 as an Assistant Professor. He is currently a Professor at the same institute in Kaohsiung, Taiwan. His research focuses on the design, positioning, and navigation of underwater vehicles. His current work includes the development of various underwater platforms, including remotely operated vehicles (ROVs), autonomous underwater vehicles (AUVs), and human-occupied vehicles (HOVs).

Authors:

Hsin-Hung Chen Institute of Undersea Technology, National Sun Yat-sen University
Ting-Ting Pai Institute of Undersea Technology, National Sun Yat-sen University
Chau-Chang Wang Institute of Undersea Technology, National Sun Yat-sen University