Four-Legged Soft Robot Operates on Pressurized Air Alone

The quadruped could be handy in environments where using electronics is dangerous or simply impossible.
Fabienne Lang
Electronics-free robotUC San Diego

Engineers have created a four-legged soft robot that moves without the use of electronics — it purely operates on pressurized air. 

The team at the University of San Diego's Jacobs School of Engineering shared the details of its invention in the journal Science Robotics on February 17.

Literally all this soft robot needs is a constant source of pressurized air for its four limbs to move. Pure and simple. 

Although, it isn't such a simple process to develop such a robot. Most soft robots already operate using pressurized air, but they also require some form of an electronic circuit in order to function. 

"This work represents a fundamental yet significant step towards fully-autonomous, electronics-free walking robots," said Dylan Drotman, lead author of the study. 

And indeed it is. This type of soft robot has a number of potentially interesting uses, ranging from low-cost toys to working in environments that don't enable electronics to work, such as mine shafts and MRI machines. What's great about such robots is that they're safe to use in close proximity to humans and can easily adapt to their environments. 

How the soft robot works

Inspired by nature, the four-legged soft robot mimics mammalian reflexes that use neural responses from the spine rather than the brain.

The robot is controlled by a lightweight, affordable system of pneumatic circuits made up of tubes and soft valves, which enable the robot to move and respond to signals it picks up in its environment. 

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The team built a system of three valves that act as oscillators, which control the order of when pressurized air enters each of its four limbs. The gait of the robot, which has two diagonal limbs moving together, was inspired by sideneck turtles' movements. 

Each of the robot's four legs has three degrees of freedom powered by three muscles. When pressurized air enters one chamber, the leg bends in the opposite direction. 

It makes for a rather awkward gait, but the fact that a soft robot can move and sense what's in its environment, turning around or sideways when confronted by an object, without using any electronics is impressive. 

The team's next steps include working on the robot's gait so that it's able to walk on uneven ground and natural terrain.