A team from the University of Washington has created a penny-sized, self-driving robot that is powered by light and radio waves.

The so-called MilliMobile features a solar panel-like energy harvesting device and is mounted on four wheels, enabling it to travel an estimated 30 feet an hour. Additionally, the robot is capable of driving across assorted terrain including concrete and packed soil, and it can reportedly carry equipment like cameras and sensors weighing up to roughly three times its own weight.

Source: Mark Stone/University of Washington

Further, MiliMobile uses a light sensor to automatically move toward light sources, running 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 available," the researchers explained. "With MilliMobile, we applied this concept to motion. We reduced the robot's size and weight so it takes only a small amount of energy to move. And, similar to an animal taking steps, our robot moves in discrete increments, using small pulses of energy to turn its wheels."

MilliMobile was tested both indoors and outdoors — in parks, an indoor hydroponic farm and an office, for instance — as well as in very low light settings, where the robot is still capable of moving, though at a much slower pace.

According to MilliMobile’s developers, the penny-sized robot is designed to sample data at various points within a space to create a more detailed picture of the environment it is surveying — such as a smart farm where it would track humidity and soil moisture.

MilliMobile also features light, temperature and humidity sensors in addition to Bluetooth, which enables the robot to transmit data over 650 ft.

A study detailing the robot, “MilliMobile: An Autonomous Battery-free Wireless Microrobot,” was presented at the ACM MobiCom 2023 conference in Madrid, Spain, on October 2, 2023.

For more on the MilliMobile robot, watch the accompanying video, which appears courtesy of the University of Washington.