Ghostlike Robot Goes for All-Terrain Action

The robot is inspired by the flatworm, an organism with a sheet-like body that lives in watery or moist terrestrial environments. Click to enlarge this image. Takeshi Kano, Tohoku University
Takeshi Kano, Tohoku University

A flat, undulating robot could move effortlessly along land, air and sea.

Call it Casper the Friendly Bot. Japanese roboticists are developing a two-dimensional sheet intended to move autonomously along land, air and sea. This ghostlike robot would be able to go where other bots won't venture.

"The advantage of this robot is that it can adapt to the environment and move on various terrains in real time," said Takeshi Kano, an assistant professor at Tohoku University's Research Institute of Electrical Communication who is creating the robot with professor Akio Ishiguro and masters student Yuki Watanabe. They recently published a paper about the robot in the journal Bioinspiration and Biomimetics (abstract).

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When Kano and his colleagues looked at existing multi-terrestrial robots, they noticed a key limitation: Specific control schemes had to be created for walking, swimming, and flying. The robots couldn't adapt in real-time. First the group studied snakes to get ideas about potential robot locomotion because a snake glides forward by pushing its body against the ground, similar to ice-skating.

Then a friend told them about flatworms, organisms with sheet-like bodies that live in watery or moist terrestrial environments. The parasitic ones, such as tapeworms, can cause all kinds of health problems for humans and animals. But Kano, Ishiguro, and Watanabe were more interested in the flatworm's movement. To replicate it, they up with a mechanism Kano described as virtual snakes tied together. Picture a "snake grid" with five skinny snakes in parallel connected to five running in the other direction.

The team also came up with what they call a fundamental principle, where any type of locomotion is realized by obtaining reaction forces from the environment. In other words, the robot would have entirely distributed control that allows it to adapt on the fly, encountering any irregularities in terrain simply as new scaffolds to move across.

So far computer simulations show the robot could move efficiently in unknown terrain. The roboticists also created a basic prototype that can move in one direction. Next they plan to make one that can go in multiple directions, Kano said. "We would like to improve the robot so that it can move in water and air," he added.

Cecilia Laschi, an associate professor of biorobotics at the Scuola Superiore Sant'Anna in Pisa, is leading a project to construct a soft-bodied robotic octopus intended for search-and-rescue. She noted that the sheet-bot remains in the modeling phase. "But it gives an important mathematical basis for eventually building and, above all, controlling such a robot."

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The biggest challenge Laschi envisioned for the group involves actuators, a bottleneck she said is common in biomimetic robotics. Unlike motors used in traditional robotics, these actuators will need to be able to contract soft structures the same way muscles do.

"At this moment it is a research prototype, but has enormous potential," said Rolf Pfeifer, a computer science professor specializing in robotics and artificial intelligence at the University of Zurich. Such an adaptable robot could be extremely useful for exploring and inspecting dangerous and unknown terrain, he added.

Pfeizer just wishes the group had chosen a more attractive species, he said. "Flatworms aren't exactly to my taste."