RetroSphere: Enabling Low-power and Affordable 3D Input for Lightweight Augmented Reality Devices

RetroSphere introduces a self-contained 6-degree-of-freedom (6DoF) controller tracker, designed for seamless integration with resourceconstrained Augmented Reality (AR) devices such as AR glasses and smartphones. This system employs a tracking mechanism using one to three retro-reflective spheres on a passive controller, thus eliminating the need for any onboard electronics or batteries. Detection is enabled by a stereo pair of mass-produced infrared blob trackers, each outfitted with infrared LED emitters. The system utilizes a lightweight stereo depth-estimation algorithm on an Arduino-compatible ESP32 microcontroller to achieve 6DoF tracking. RetroSphere achieves a tracking accuracy of approximately 96.5%, with positional errors as low as 3.5 cm across a tracking range of 100 cm, while maintaining a power consumption of just about 400 mW. The complete hardware and firmware details for RetroSphere are available as open source on GitHub: https://github.com/AnantaBalaji/RetroSphere