PointRing: Enabling Calibration-Free Pointing Interaction in Smart Homes with a UWB-IMU Smart Ring

Pointing provides a direct and intuitive mechanism for selecting and controlling devices in multi-device smart homes. However, existing wrist-worn approaches often suffer from high deployment overhead and degraded reliability due to orientation drift and repeated recalibration. We present PointRing , a smart ring that fuses Ultra-Wideband (UWB) and Inertial Measurement Unit (IMU) sensing to enable calibration-free, drift-resistant pointing-based device selection. PointRing introduces two core components: TRA (Trajectory-based Ray Alignment), a trajectory-driven fusion method that infers and refines pointing rays from UWB localization and IMU motion traces without relying on absolute attitude calibration, and SnapMap , a lightweight deployment tool that uses smartphone-captured RGB-D images to register three UWB anchors and device locations for rapid deployment and redeployment. Across a controlled laboratory and a real home environment with six devices, PointRing achieves an overall device selection accuracy of 94.86%. Full deployment takes 117-165 s, while single-device redeployment takes 15-19 s. A user study with 43 participants further characterizes the deployment workflow and interaction tradeoffs, and reveals that PointRing effectively complements commercial smart speakers in typical home scenarios—particularly for spatial disambiguation and fine-grained control.