Pedestrian navigation fusing inertial and RSS/TOF measurements with adaptive movement/measurement models: Experimental evaluation and theoretical limits

Francisco Zampella, Alfonso Bahillo, Javier Prieto, Antonio R. Jiménez, Fernando Seco
2013 Sensors and Actuators A-Physical  
A common approach for advanced Indoor Localization systems is the fusion of complementary techniques, such as inertial navigation systems like Pedestrian Dead-Reckoning (PDR) and absolute measurement methods like radio-frequency (RF) beacon-based positioning. Although this fusion approach provides accurate drift-free absolute positioning, the best results are only obtained if the techniques are adapted to each environment and user. This requires a previous campaign of building calibration and
more » ... vement model estimation that will be specific to the place and person. In this paper, we tackle this problem by presenting a real-time pedestrian navigation system that fuses PDR and RF beacon-based strategies using a flexible particle filter (PF) implementation, with the following innovative aspects: 1) the definition of an adaptive stride movement model valid for different walking styles, which is used in the PF prediction stage; 2) the dynamic estimation of the measurements model from real-time Received Signal Strength (RSS) and Time of Flight (TOF) values, which is used in the PF update stage; 3) the tracking of the person's position without an initial position/heading nor specific calibration. Additionally, we have obtained the Cramér-Rao lower bound (CRLB) for our fusion-based approach, in order to assess rigorously the performance of the positioning accuracy. We have tested the system in a building fusing PDR with TOF and RSS values coming from WiFi access points or ZigBee nodes. For trajectories with a total length of approximately 1000 m we obtained an error of less than 1.75 m for 90 % of the total path length, with both systems. The empirical results match closely the CRLB, showing that our system performs close to the theoretical limit.
doi:10.1016/j.sna.2013.08.028 fatcat:bh57glrm2nbrhh3tzpiuwyxgcy