AUVs commonly use digital displays to communicate with divers. However, digital displays are hard to read at a distance or at an angle.
In order to allow communication at further distances, we have previously proposed Robot Communication Via Motion, and now we present a light-based communication method called HREye.
![The HREye system operating on board LoCO](/sites/irvlab.cs.umn.edu/files/2022-11/loco_hreye.png)
![The evolution of light-based communication for AUVs.](/sites/irvlab.cs.umn.edu/files/2022-11/led_evolution.png)
Our HREye system was developed to take advantage of the long distances at which light can travel in adequate visibility underwater. We also wanted to take advantage of a wide array of colors and of the shape in which these lights are arranged. A sequence of light animations on the HREyes is called a luceme.
![The active lucemes of HREye](/sites/irvlab.cs.umn.edu/files/2022-11/active_lucemes.png)
Active lucemes communicate a single piece of information, and perform only slightly less accurately than a digital display (OLED). Even people who haven't been trained on the meaning of lucemes can identify them with relative accuracy.
![Comparison between HREye, Untrained HReye, and OLED conditions.](/sites/irvlab.cs.umn.edu/files/2022-11/condition_compare.png)
![Comparison between HREye accuracy and operational accuracy for communicaiton phrases.](/sites/irvlab.cs.umn.edu/files/2022-11/per_lucemes.png)
However, HREyes are capable of more than just active lucemes. In ocular mode, an HREye can mimic the blinking and gaze directions of a human eye
![The ocular lucemes of the HREye device](/sites/irvlab.cs.umn.edu/files/2022-11/ocular_lucemes.png)
The chart below shows that people can identify the gaze direction of ocular lucemes, with a small amount of error (average 21◦).
![Results of gaze indication using HREye.](/sites/irvlab.cs.umn.edu/files/2022-11/ocular_results.png)