SurferBot: A wave-propelled aquatic vibrobot
Eugene Rhee, Robert Hunt, Stuart J. Thomson, and Daniel M. Harris
Bioinspiration and Biomimetics, 2022
Overview
Inspired by a survival mechanism initiated by the honeybee trapped on the surface of water, we present the SurferBot: a centimeter-scale vibrating robotic device that self-propels on a fluid surface. This low-cost and easily assembled device is capable of rectilinear motion thanks to forces arising from a wave-generated, unbalanced momentum flux, achieving speeds on the order of centimeters per second. The SurferBot can be used to explore fundamental aspects of active and driven particles at fluid interfaces, as well as in robotics and fluid mechanics pedagogy.
What happens if you take an asymmetric mass and vibrate it in the water?
It moves! Fun, but why?
When you shake something in the water, the oscillating body generates surface waves that carry excess momentum with them. The waves are larger in the back than in the front, leading to a net forward thrust. This asymmetry results from the rearward motor position.
The unbalanced response generates larger waves at the back, propelling the Surferbot forward!
Prototyping and Fabrication
Upon joining the Harris lab, I was presented with the concept of an asymmetric mass vibrating in the water. For two years, I iterated on fabrication of the SurferBot, explored different methods of vibration, and how to secure all electronic components securely on the boat. Discovering and observing the key factors in SurferBot movement, such as boat shape and mass asymmetry placements, was my guiding direction.
Challenges
Navigating an ambiguous space and trying to draw conclusions is always a challenge. Some other difficulties I faced were finding a consistent SurferBot fabrication method, inconsistency in motor speeds, and a reliable SurferBot launching method.
No matter the challenges, I had a great time working on this project. I absolutely loved stepping into a completely new and complex space, and building my own intuition around it through experiments and observation. I'm incredibly lucky to have been with a team of people who have always supported me - and the SurferBot - on days where nothing worked and on days where everything worked. My team has taught me to not be afraid of asking questions, and to always stay lighthearted and make the work fun.
Video
Upon finalizing our results and submitting a paper, I created a video on the SurferBot, which was a great exercise in telling a story around a complex subject. I loved creating something engaging that was more digestible than a research paper, and able to reach a broader community.
thank you!
Team
special thanks to Dan Harris, Stuart J. Thomson, Robert Hunt, Luke Alventosa and Jack-William Barotta! 😊
