Robohub.org
 

Next-generation robotic cockroach can explore under water environments


by
25 July 2018



share this:

When HAMR needs to sink, its footpads emit a high voltage to break the water surface tension. This process is called electrowetting, which is the reduction of the contact angle between a material and the water surface under an applied voltage. This change of contact angle makes it easier for objects to break the water surface. (Credit: Yufeng Chen, Neel Doshi, and Benjamin Goldberg/Harvard University)

By Leah Burrows

In nature, cockroaches can survive underwater for up to 30 minutes. Now, a robotic cockroach can do even better. Harvard’s Ambulatory Microrobot, known as HAMR, can walk on land, swim on the surface of water, and walk underwater for as long as necessary, opening up new environments for this little bot to explore.

This next generation HAMR uses multifunctional foot pads that rely on surface tension and surface tension-induced buoyancy when HAMR needs to swim but can also apply a voltage to break the water surface when HAMR needs to sink. This process is called electrowetting, which is the reduction of the contact angle between a material and the water surface under an applied voltage. This change of contact angle makes it easier for objects to break the water surface.

Moving on the surface of water allows a microrobot to evade submerged obstacles and reduces drag. Using four pairs of asymmetric flaps and custom designed swimming gaits, HAMR robo-paddles on the water surface to swim. Inspired by the gait of a diving beetle, the researchers exploited the unsteady interaction between the robot’s passive flaps and the surrounding water to effectively swim forward and turn.

“This research demonstrates that microrobotics can leverage small-scale physics — in this case surface tension — to perform functions and capabilities that are challenging for larger robots,” said Kevin Chen, Ph.D., a postdoctoral fellow at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and first author of the paper.

The most recent research is published in the journal Nature Communications.

“HAMR’s size is key to its performance,” said Neel Doshi, graduate student at SEAS and co-author of the paper. “If it were much bigger, it would be challenging to be support the robot with surface tension and if it were much smaller, the robot would need a lot more force to break it.”

HAMR weighs 1.65 grams (about as much as a large paper clip), can carry 1.44 grams of additional payload without sinking and can paddle its legs with a frequency up to 10 Hz. It’s coated in Parylene to keep it from shorting under water.

Once below the surface of the water, HAMR uses the same gait to walk as it does on dry land and is just as mobile. Getting out of the water, however, is an enormous challenge. The water’s surface tension force is twice HAMR’s weight and the induced torque causes a dramatic increase of friction on the robot’s hind legs. The researchers stiffened the robot’s transmission and installed soft pads to the robot’s front legs to increase payload capacity and redistribute friction during climbing. Finally, walking up a modest incline, the robot is able break out of the water’s hold.

Havard’s Ambulatory Microrobot (HAMR) joins the Robobee (right) as a microrobot that can transition between air and water (Credit: Yufeng Chen, Neel Doshi, and Benjamin Goldberg/Harvard University)

“This robot nicely illustrates some of the challenges and opportunities with small-scale robots,” said senior author Robert Wood, Ph.D., Core Faculty member at the Wyss Institute for Biologically Inspired Engineering and the Charles River Professor of Engineering and Applied Sciences at Harvard’s Paulson School of Engineering and Applied Sciences. “Shrinking brings opportunities for increased mobility – such as walking on the surface of water – but also challenges since the forces that we take for granted at larger scales can start to dominate at the size of an insect.”

Next, the researchers hope to further improve HAMR’s locomotion and find a way to return to land without a ramp, perhaps incorporating gecko-inspired adhesives or impulsive jumping mechanisms.

This research was co-authored by Benjamin Goldberg and Hongqiang Wang, Ph.D.. It was supported by the Wyss Institute for Biologically Inspired Engineering, the Harvard John A. Paulson School of Engineering and Applied Science, and the Office of Naval Research’s Defense University Research Instrumentation Program.




Wyss Institute uses Nature's design principles to develop bioinspired materials and devices that will transform medicine and create a more sustainable world.
Wyss Institute uses Nature's design principles to develop bioinspired materials and devices that will transform medicine and create a more sustainable world.





Related posts :



Robot Talk Episode 115 – Robot dogs working in industry, with Benjamin Mottis

  28 Mar 2025
In the latest episode of the Robot Talk podcast, Claire chatted to Benjamin Mottis from ANYbotics about deploying their four-legged ANYmal robot in a variety of industries.

Robot Talk Episode 114 – Reducing waste with robotics, with Josie Gotz

  21 Mar 2025
In the latest episode of the Robot Talk podcast, Claire chatted to Josie Gotz from the Manufacturing Technology Centre about robotics for material recovery, reuse and recycling.

Robot Talk Episode 113 – Soft robotic hands, with Kaspar Althoefer

  14 Mar 2025
In the latest episode of the Robot Talk podcast, Claire chatted to Kaspar Althoefer from Queen Mary University of London about soft robotic manipulators for healthcare and manufacturing.

Robot Talk Episode 112 – Getting creative with robotics, with Vali Lalioti

  07 Mar 2025
In the latest episode of the Robot Talk podcast, Claire chatted to Vali Lalioti from the University of the Arts London about how art, culture and robotics interact.

Robot Talk Episode 111 – Robots for climate action, with Patrick Meier

  28 Feb 2025
In the latest episode of the Robot Talk podcast, Claire chatted to Patrick Meier from the Climate Robotics Network about how robots can help scale action on climate change.

Robot Talk Episode 110 – Designing ethical robots, with Catherine Menon

  21 Feb 2025
In the latest episode of the Robot Talk podcast, Claire chatted to Catherine Menon from the University of Hertfordshire about designing home assistance robots with ethics in mind.

Robot Talk Episode 109 – Building robots at home, with Dan Nicholson

  14 Feb 2025
In the latest episode of the Robot Talk podcast, Claire chatted to Dan Nicholson from MakerForge.tech about creating open source robotics projects you can do at home.

Robot Talk Episode 108 – Giving robots the sense of touch, with Anuradha Ranasinghe

  07 Feb 2025
In the latest episode of the Robot Talk podcast, Claire chatted to Anuradha Ranasinghe from Liverpool Hope University about haptic sensors for wearable tech and robotics.





Robohub is supported by:




Would you like to learn how to tell impactful stories about your robot or AI system?


scicomm
training the next generation of science communicators in robotics & AI


©2024 - Association for the Understanding of Artificial Intelligence


 












©2021 - ROBOTS Association