UWB TDoA Error Correction using Transformers: Patching and Positional Encoding Strategies
This addresses localization errors for UWB systems in complex industrial settings, representing an incremental advance with specific performance gains.
The paper tackles inaccuracies in UWB-based localization in industrial environments with obstacles by proposing a transformer-based TDoA correction method using raw channel impulse responses, achieving up to 0.39 m accuracy in NLOS conditions, a 73.6% improvement over the baseline.
Despite their high accuracy, UWB-based localization systems suffer inaccuracies when deployed in industrial locations with many obstacles due to multipath effects and non-line-of-sight (NLOS) conditions. In such environments, current error mitigation approaches for time difference of arrival (TDoA) localization typically exclude NLOS links. However, this exclusion approach leads to geometric dilution of precision problems and this approach is infeasible when the majority of links are NLOS. To address these limitations, we propose a transformer-based TDoA position correction method that uses raw channel impulse responses (CIRs) from all available anchor nodes to compute position corrections. We introduce different CIR ordering, patching and positional encoding strategies for the transformer, and analyze each proposed technique's scalability and performance gains. Based on experiments on real-world UWB measurements, our approach can provide accuracies of up to 0.39 m in a complex environment consisting of (almost) only NLOS signals, which is an improvement of 73.6 % compared to the TDoA baseline.