FaceOri: Tracking Head Position and Orientation Using Ultrasonic Ranging on Earphones

TL;DR

FaceOri is a novel ultrasonic-based face tracking system using earphones that accurately determines head orientation and distance, enabling improved hands-free device control and context-aware interactions.

Contribution

This paper introduces FaceOri, a new ultrasonic ranging technique for head tracking using commodity earphones, achieving high accuracy in orientation and distance estimation.

Findings

93.5% accuracy within 1.5 meters range

Median absolute error of 10.9 mm in distance

3.7° yaw and 5.8° pitch error in head orientation

Abstract

Face orientation can often indicate users' intended interaction target. In this paper, we propose FaceOri, a novel face tracking technique based on acoustic ranging using earphones. FaceOri can leverage the speaker on a commodity device to emit an ultrasonic chirp, which is picked up by the set of microphones on the user's earphone, and then processed to calculate the distance from each microphone to the device. These measurements are used to derive the user's face orientation and distance with respect to the device. We conduct a ground truth comparison and user study to evaluate FaceOri's performance. The results show that the system can determine whether the user orients to the device at a 93.5% accuracy within a 1.5 meters range. Furthermore, FaceOri can continuously track the user's head orientation with a median absolute error of 10.9 mm in the distance, 3.7 degrees in yaw, and 5.8 degrees in pitch. FaceOri can allow for convenient hands-free control of devices and produce more intelligent context-aware interaction.