Robust Absolute Headset Tracking for Extended Reality

This paper presents a novel headset tracking frame-work designed for extended reality (XR) applications. The growth of XR demands accurate and robust tracking mechanisms that are suitable for both indoor and outdoor environments and offer anchoring to a global reference frame. By loosely coupling a visual simultaneous localization and mapping (SLAM) algorithm to a tightly-coupled carrier phase differential GNSS (CDGNSS) and inertial sensor subsystem, the proposed system aims to achieve centimeter-accurate, globally-referenced tracking that persists during extended periods of GNSS degradation. Collaborative and persistent XR experiences are enabled through accurate map creation utilizing a bundle adjustment approach for map generation and maintenance. Cloud or near-edge offloading of computationally demanding steps in the pipeline is explored to reduce the computational demand on the headset. Robust tracking performance is evaluated in terms of odometric drift under GNSS outages. This paper also explores the benefit of additional headset tracking constraints offered by direction-of-arrival measurements to nearby cellular base stations. Such measurements will become available as future wireless standards make increasing use of mmWave frequencies.