MilliMobile is a first of its kind battery-free autonomous robot capable of operating on harvested solar and radio frequency power. The MilliMobile prototype has a 1 x1 cm chassis and weighs less than 1.1 g. It can carry payloads 3 times its own weight, and only experiences a 25% reduction in speed when carrying a 1 g payload.
Small mobile robots carrying sensors could perform tasks like catching gas leaks or tracking warehouse inventory.
But moving robots demands a lot of energy, and batteries, the typical power source, limit lifetime and raise environmental concerns.
Researchers have explored various alternatives: affixing sensors to insects, keeping charging mats nearby, or powering the robots with lasers.
Each has drawbacks. Insects roam. Chargers limit range. Lasers can burn people’s eyes.
“We challenge the conventional assumption that motion and actuation are beyond the capabilities of battery-free devices and demonstrate completely untethered autonomous operation in realistic indoor and outdoor lighting as well as radio frequency delivery scenarios,” said University of Washington doctoral student Kyle Johnson and colleagues, who developed MilliMobile, a tiny, self-driving robot powered only by surrounding light or radio waves.
Equipped with a solar panel-like energy harvester and four wheels, their robot is about the size of a penny, weighs as much as a raisin and can move about the length of a bus (10 m, or 30 feet) in an hour even on a cloudy day.
MilliMobile can drive on surfaces such as concrete or packed soil and carry three times its own weight in equipment like a camera or sensors.
It uses a light sensor to move automatically toward light sources so it can run indefinitely on harvested power.
“We took inspiration from ‘intermittent computing,’ which breaks complex programs into small steps, so a device with very limited power can work incrementally, as energy is…
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