Scientists engineer centipede-inspired wiggling robots that tackle tough terrains

The researchers developed a theory that proposes adding pairs of legs to the robot increases its ability to move robustly over challenging surfaces — a concept they call spatial redundancy.
Loukia Papadopoulos
An image of the centipede robot.jpg
An image of the centipede robot.

Georgia Tech 

A team of physicists, engineers, and mathematicians at the Georgia Institute of Technology are mimicking centipedes’ movements to develop a new theory of multilegged locomotion. Through their experiments, they discovered that robots with more legs could move across uneven surfaces with agility without any additional sensing or control technology.

This is according to a press release by the institution published on Friday.

“When you see a scurrying centipede, you're basically seeing an animal that inhabits a world that is very different than our world of movement,” said Daniel Goldman, the Dunn Family Professor in the School of Physics. 

“Our movement is largely dominated by inertia. If I swing my leg, I land on my foot, and I move forward. But in the world of centipedes, if they stop wiggling their body parts and limbs, they basically stop moving instantly.”

The team of researchers developed a theory that proposes that adding leg pairs to the robot increases its ability to move robustly over challenging surfaces — a concept they call spatial redundancy. 

This results in robot legs that are successful on their own without the need for sensors to interpret the environment. If one leg fails, the rest keeps it moving regardless. 

Search and rescue and more

“With an advanced bipedal robot, many sensors are typically required to control it in real-time,” said Baxi Chong, a physics postdoctoral researcher.

 “But in applications such as search and rescue, exploring Mars, or even micro-robots, there is a need to drive a robot with limited sensing. There are many reasons for such sensor-free initiative. The sensors can be expensive and fragile, or the environments can change so fast that it doesn’t allow enough sensor-controller response time.”

To test the theory, the researchers built a wildly uneven terrain and had robots navigate it, increasing their number of legs by two each time, starting with six and eventually expanding to 16. The scientists found that as the leg count increased, the robot could more agilely move across the terrain, even without sensors.

“It's truly impressive to witness the multilegged robot's proficiency in navigating both lab-based terrains and outdoor environments,” said in the statement Juntao He, a Ph.D. student in robotics.

“While bipedal and quadrupedal robots heavily rely on sensors to traverse complex terrain, our multilegged robot utilizes leg redundancy and can accomplish similar tasks with open-loop control.”

The study was published in Proceedings of the National Academy of Sciences in March.

Study abstract:

Whereas the transport of matter by wheeled vehicles or legged robots can be guaranteed in engineered landscapes such as roads or rails, locomotion prediction in complex environments such as collapsed buildings or crop fields remains challenging. Inspired by the principles of information transmission, which allow signals to be reliably transmitted over “noisy” channels, we developed a “matter-transport” framework that demonstrates that noninertial locomotion can be provably generated over noisy rugose landscapes (heterogeneities on the scale of locomotor dimensions). Experiments confirm that sufficient spatial redundancy in the form of serially connected legged robots leads to reliable transport on such terrain without requiring sensing and control. Further analogies from communication theory coupled with advances in gaits (coding) and sensor-based feedback control (error detection and correction) can lead to agile locomotion in complex terradynamic regimes.

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