WP4 SafePASS Indoor localization techniques
Within the project’s WP4 “SafePASS Smart Environment” our consortium partner Telesto, supported by NTUA, is implementing an indoor localization solution for cruise ships aiming at providing knowledge of each passenger’s exact position within the ship’s area during the different evacuation phases. As part of this activity, both Telesto and NTUA performed several UWB-based measurement campaigns in different environments and set-ups. In particular, the indoor localization solution based on Ultra-Wide Band technology has being assessed with respect to location accuracy in line-of-sight (LoS) and non-line-of-sight (NLoS) conditions as well as in different deployment scenarios. The results are promising both with respect to the achieved location accuracy and the performance of UWB in case of multipath interference.
The measurement campaigns that have been conducted during the last months were realized in a commercial mall venue where anchors where placed at several floors, as well as in an office environment with corridors and metallic doors (Figure 1).
Figure 1 Placement of Anchors within the Commercial Mall
The UWB solution that is being implemented is based on Decawave’s DWM1001 development board (Figure 2)
Figure 2: Raspberry Pi 3 model B and Decawave DWM1001 Board Connection
As an example Figure 3 is presented, showing a general top-down view for different measurement positions from the shopping mall installation, which illustrates that the location accuracy is high in line-of-sight conditions within the anchors-defined polygon (Positions A, C, D), even in cases where one anchor is in NLoS to the tag (Position B) or even in large distances outside the anchors-defined polygon (Position E). A special case is when the user’s body blocks the tag from all anchors leading to total NLoS conditions (Position E at the “rotation” points), where the location error increases dramatically over-exceeding 1 meter, rendering the application not acceptable.
Figure 3 – Measurement Results in LoS Conditions for All Positions
Another interesting case is under the presence of multiple vertical-axis networks, where different independent networks are installed at vertical levels, e.g. at different floors of a building, where the location is estimated with significant error because of signals reflected from one network to the other, leading to multipath interference effects.
Towards the realization of the 1st SafePASS indoor localization solution further analysis and measurement campaigns will be conducted in ship relevant environment analysing further the optimum set-up of anchors and performance of the indoor solutions under certain extreme conditions.