Table of Contents
ISRN Robotics
Volume 2013 (2013), Article ID 541643, 7 pages
Research Article

New Volume Change Mechanism Using Metal Bellows for Buoyancy Control Device of Underwater Robots

Department of Mechanical and Systems Engineering, Ryukoku University, 1-5 Yokotani, Seta Oe, Shiga, Otsu 520-2194, Japan

Received 30 November 2012; Accepted 19 December 2012

Academic Editors: G. C. Gini, D. M. Lyons, and D. K. Pratihar

Copyright © 2013 Koji Shibuya and Sho Yoshii. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We propose a new volume change mechanism using a metal bellows for a buoyancy control device of underwater robots and vehicles. Our proposed buoyancy control method utilizes the volume change caused by the phase-change of materials. We chose paraffin wax as a phase-change material because its volume change exceeds other candidates. Our proposed device consists of a metal bellows and an aluminum housing that contains paraffin wax and water. The paraffin wax is heated and cooled by a nichrome wire and a peltier device. We conducted two experiments and confirmed that the heat sink in the aluminum housing increases the speed of the buoyancy change and that the thickness of the air layer is crucial for efficient insulating. Then, we built a prototype robot with the four devices and confirmed that the robot can change its buoyancy up to its maximum value.