Flailing tube man-inspired robot uses no electronics

Engineers have harnessed the physics behind the flailing tube men to power a tiny soft “robot” capable of walking, hopping, and swimming. Plus their motion mechanism doesn’t need software, sensors, or any form of artificial intelligence. But even with its relative simplicity, the robot’s creators hope the new design will one day find its way into everything from smart pills to space technology. The research is detailed in a study published May 8 in the journal Science.

The key to the machine’s functionality and adaptability can be found in its set of four soft, tubular legs. Much like those dancing used car advertisements, the robot is powered by a continuous stream of air. While each leg would flail at random on their own, fluid physics dictate a different scenario when the limbs work together. After a moment of calibration, the machine naturally transitions into a rhythmic gait.

“Suddenly, order emerges from chaos,” explained Alberto Comoretto, the study’s first author and a researcher at the Netherlands’ Institute for Atomic and Molecular Physics (AMOLF). “There’s no code, no instructions. The legs simply fall into sync spontaneously, and the robot takes off.

The design also isn’t stuck in its synchronous pattern once it starts. Instead, it adapts. For example, continuous airflow allows the machine to reorient itself after running into an obstacle, as well as switch from land to water by adopting a freestyle pattern of movement. In doing so, the invention showcases a form of “decentralized intelligence” that’s often seen in the natural world.

“Sea stars, for example, coordinate hundreds of tube feet using local feedback and body dynamics, not a centralized brain,” said co-author Mannus Schomaker.

The low-energy design is also comparatively fast. At its maximum speed, the machine tops out at 30 body lengths per second. Compare that (in relative terms) to a Ferrari, which hits 20 lengths per second. Taken altogether, the designers believe their creation offers a promising alternative to far more expensive robots that require heavy-duty equipment and programming—often at exponentially higher cost.

The implications go far beyond miniature flailing tube men. Future mechanisms that harness airflow physics could find their way into microrobot “smart pills” capable of safely traveling to a target tissue before releasing drugs, or wearable exosuits that sync to a user’s movements without computer processors. Getting rid of delicate electronics could also allow mechanical machines to operate in extreme environments like space.

“Simple objects, like tubes, can give rise to complex and functional behavior, provided we understand how to harness the underlying physics,” said principal investigator Bas Overvelde. “There is no brain, no computer. Essentially, it’s a machine. But when properly designed, it can outperform many robotic systems and behave like an artificial creature.”