Battery-free Eye Tracker on the Horizon
Jeffrey Heimgartner posted on November 13, 2018 |

For augmented reality (AR) enthusiasts, current wearable eye trackers are often expensive and bulky. The cameras needed to capture images require battery power for the massive amount of image processing necessary to work, resulting in high-energy consumption.

A Dartmouth University research team is working to create eye trackers for glasses that are cost effective and battery free. According to the team’s research, their eye-trackers  eliminate the consumption issue thanks to using solar cells as the power source. Their wearable system is energy efficient and tracks rapid eye movements, all while providing hands-free control and improving image display accuracy.

“This is an exciting advancement for gamers, developers and other users of smart glasses,” said Xia Zhou, Dartmouth University associate professor of computer science and project lead. “It’s the first-ever eye tracker that can fit into your everyday glasses and run without batteries.”

Battery-free eye-trackers for everyday glasses are outfitted with NIR LEDs, photodiodes and a MINI-M4 FOR MSP432 board, which are powered by solar cells. (Image courtesy of Dartmouth University.)
Battery-free eye-trackers for everyday glasses are outfitted with NIR LEDs, photodiodes and a MINI-M4 FOR MSP432 board, which are powered by solar cells. (Image courtesy of Dartmouth University.)

To create the eye-tracker system, the team used a custom PCB populated with six NIR LEDs and 12 photodiodes, MINI-M4 FOR MSP432 microcontroller, and thin-film solar cells and attached it to store-bought glasses. The solar cells are placed vertically on the side of the glasses’ arms to absorb light energy. Angled LEDs help illuminate the users left eye from various angles, while the photodiodes detect reflected light patterns. Custom algorithms allow the microcontroller to analyze the patterns and precisely determine the pupil’s position—including trajectory, velocity and acceleration— and diameter in real-time.

The team’s prototype tracks four stages of eye movement: fixation, smooth pursuit, saccade and blinking. Their experiments, which were conducted indoors to ensure the sensors weren’t saturated with light, yielded positive results for accuracy and tracking.

“By detecting the type of eye movement, the system can adapt sensing and computation. Some movements have predictable trajectories, allowing the system to infer subsequent pupil position and minimizing energy use,” said Tianxing Li, doctoral student and research paper author.

The team believes their research can provide benefits beyond power consumption. The eye trackers can be created at a much lower cost and integrated easier into standard glasses. The team plans to continue their research into eye tracking, which could potentially be used to help identify health issues. They also plan on reducing the size of the system for a better fit with different styles of glasses, as well as diving into exploring how to adapt it to outdoor use.

Interested in more AR/VR innovations? Check out AR Comes to Motorcycle Riding and The Future of Virtual Reality Features Resolution of the Human Eye.


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