Rethinking Orientation Estimation with Smartphone-equipped Ultra-wideband Chips

While localization has gained a tremendous amount of attention from both academia and industry, much less attention has been paid to equally important orientation estimation. Traditional orientation estimation systems relying on gyroscopes suffer from cumulative errors. In this paper, we propose UWBOrient, the first fine-grained orientation estimation system utilizing ultra-wideband (UWB) modules embedded in smartphones. The proposed system presents an alternative solution that is more accurate than gyroscope estimates and free of error accumulation. We propose to fuse UWB estimates with gyroscope estimates to address the challenge associated with UWB estimation alone and further improve the estimation accuracy. UWBOrient decreases the estimation error from the state-of-the-art 7.6° to 2.7° while maintaining a low latency (20 ms) and low energy consumption (40 mWh). Comprehensive experiments with both iPhone and Android smartphones demonstrate the effectiveness of the proposed system under various conditions including natural motion, dynamic multipath and NLoS. Two real-world applications, i.e., head orientation tracking and 3D reconstruction are employed to showcase the practicality of UWBOrient.