Four-legged robot eschews electronics for air power
Image credit: University of California San Diego
A four-legged soft robot has been prototyped that doesn’t require any electronics; a constant source of pressurised air supports all its functions, including its controls and locomotion.
Most soft robots are powered by pressurised air via pneumatic actuators, controlled by circuits.
However, engineers at the University of California San Diego are trying to avoid using complex electronic components, which constitute the robot’s brains and nervous system, as they are typically bulky and expensive.
Their robot is controlled by a light-weight, low-cost system of pneumatic circuits of tubes and soft valves, onboard the robot itself. The robot can walk on command or in response to stimuli from the environment.
“This work represents a fundamental yet significant step towards fully-autonomous, electronics-free walking robots,” said researcher Dylan Drotmanm, the paper’s first author.
Applications include low-cost robotics for entertainment, such as toys, and robots that can operate in environments where electronics cannot function, such as MRI machines or mine shafts.
Soft robots are of particular interest because they easily adapt to their environment and operate safely near humans.
“With our approach, you could make a very complex robotic brain,” said Professor Michael Tolley, the study’s senior author. “Our focus here was to make the simplest air-powered nervous system needed to control walking.”
The robot’s computational power roughly mimics mammalian reflexes that are driven by a neural response from the spine rather than the brain. The team was inspired by neural circuits found in animals, called central pattern generators, made of very simple elements that can generate rhythmic patterns to control motions like walking and running.
To mimic the generator’s functions, engineers built a system of valves that act as oscillators, controlling the order in which pressurised air enters air-powered muscles in the four limbs. They added a component that coordinates the robot’s gait by delaying the injection of air into the robot’s legs. The robot’s gait was inspired by sideneck turtles.
The robot is also equipped with simple mechanical sensors: soft bubbles filled with fluid and placed at the end of booms protruding from the body. When the bubbles are depressed, the fluid flips a valve in the robot that causes it to reverse direction. Each limb has three chambers, and when one is pressurised, it bends in the opposite direction. This creates the multi-axis bending required for walking.
In the future, the team wants to improve the robot’s gait so it can walk on natural terrains and uneven surfaces.
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