BeSound: Bluetooth-Based Position Estimation Enhancing with Cross-Modality Distillation

TL;DR

This paper introduces BeSound, a Bluetooth-based worker localization system in smart factories that uses cross-modality distillation from ultrasound signals to improve BLE RSSI accuracy, ensuring privacy and scalability.

Contribution

The paper presents a novel knowledge distillation approach that enhances BLE-based localization accuracy by leveraging ultrasound signals without requiring additional hardware during inference.

Findings

11.79% increase in F1-score over baseline

Effective knowledge transfer from ultrasound to BLE models

Scalable, privacy-preserving worker localization solution

Abstract

Smart factories leverage advanced technologies to optimize manufacturing processes and enhance efficiency. Implementing worker tracking systems, primarily through camera-based methods, ensures accurate monitoring. However, concerns about worker privacy and technology protection make it necessary to explore alternative approaches. We propose a non-visual, scalable solution using Bluetooth Low Energy (BLE) and ultrasound coordinates. BLE position estimation offers a very low-power and cost-effective solution, as the technology is available on smartphones and is scalable due to the large number of smartphone users, facilitating worker localization and safety protocol transmission. Ultrasound signals provide faster response times and higher accuracy but require custom hardware, increasing costs. To combine the benefits of both modalities, we employ knowledge distillation (KD) from ultrasound signals to BLE RSSI data. Once the student model is trained, the model only takes as inputs the BLE-RSSI data for inference, retaining the advantages of ubiquity and low cost of BLE RSSI. We tested our approach using data from an experiment with twelve participants in a smart factory test bed environment. We obtained an increase of 11.79% in the F1-score compared to the baseline (target model without KD and trained with BLE-RSSI data only).