2022 Fiscal Year Final Research Report

Self-propulsion control of an oil droplet using chemical reaction and the application to in-water object transportation

Research Project

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Project/Area Number	19K21950
Research Category	Grant-in-Aid for Challenging Research (Exploratory)
Allocation Type	Multi-year Fund
Review Section	Medium-sized Section 20:Mechanical dynamics, robotics, and related fields
Research Institution	Waseda University
Principal Investigator	Sawada Hideyuki 早稲田大学, 理工学術院, 教授 (00308206)
Co-Investigator(Kenkyū-buntansha)	前田真吾芝浦工業大学, 工学部, 教授 (40424808) 重宗宏毅芝浦工業大学, 工学部, 准教授 (40822466)
Project Period (FY)	2019-06-28 – 2023-03-31
Keywords	油滴 / マランゴニ対流 / 化学反応 / 自走油滴 / オレイン酸 / 界面活性剤 / 形状記憶合金ワイヤ / 水中物体搬送
Outline of Final Research Achievements	This research proposed a novel directional control method of self-propelled oil droplets. Oil droplets locomote spontaneously with surfactant action. This self-propulsion is caused by Marangoni convection within the oil droplet due to differences in the surfactant concentration at the droplet surface. We paid attention to the observational facts that self-propelled oil droplets changed their locomotion styles depending on their shapes, and discovered that boomerang-shaped oil droplets performed the straight motion. In this study, we introduced exoskeletons for the directional and velocity control of oil droplets. Through experiments and simulation studies, we further discovered that the stability of the velocity and locomotion direction depended on the particular boomerang shapes, environmental temperature and humidity, and external vibratory stimuli. Our discovery was applied to a transporting robot driven only by the energy obtained from chemical reactions.
Free Research Field	ロボティクス
Academic Significance and Societal Importance of the Research Achievements	本研究では、自走油滴を流体の動きを利用した新奇なアクチュエータと見做し、これを最適に制御する手法を提案した。ソフトロボティクスの最近の研究において、流体アクチュエータが注目されており、流体の境界条件や腱となる部材を追加して束縛を増やすことで制御を試みる研究成果が報告されている。対流を利用したアクチュエータはソフトロボティクスの分野から見ても革新的であり、また油滴を物理的に変形させて自走制御する研究は、高分子の研究分野においても新奇性が高い。対流の境界条件依存性に着目し、形状を変形することで油滴を制御する試みは、分野の垣根を超えた挑戦的な研究の成果といえる。