Accurate displacement monitoring is crucial for industrial system safety, where millimeter-level shifts signal potential failures. Achieving such accuracy in a cost-effective and practical manner is challenging, as existing solutions typically depend on battery-powered devices, require fixed installations, and suffer from sensitivity to environmental variations. These limitations reduce scalability and increase maintenance overhead. We present TagTect , a battery-free displacement monitoring system leveraging passive RFID technology to achieve millimeter-level accuracy. TagTect introduces an inter-tag reflection-based sensing model, where simultaneous transmission between two tags creates a measurable inter-tag channel whose characteristics vary with their relative displacement. This mechanism enables precise tracking of small positional shifts. Combined with a customized tag deployment strategy and a collision-aware DPC-based clustering method, this design normalizes inter-tag reflections, stabilizes collision signal clustering, and ensures robust feature extraction by mitigating the effects of environmental variability, antenna placement inconsistencies, and signal misalignment. Extensive evaluations demonstrate that TagTect achieves an average displacement error of 3 mm across different positions and maintains an angle estimation error of only 2.3°, showcasing its potential as a robust, battery-free, and scalable solution for industrial displacement monitoring.
Mao et al. (Fri,) studied this question.