According to the Federal Ministry of Labour, Social Affairs and Consumer Protection, approximately 3.9% of the Austrian population suffer from permanent visual impairments. Although this quantity is respectable, this group of the Austrian society still suffers from problems, others do not even think of. One example is the daily navigation through the urban environment – traffic junctions or busy roads can become very dangerous, if one of the sensory organs is impaired. Therefore, especially blind people lack accurate and reliable navigation systems to make their daily routes safer for them.
Actual pedestrian navigation systems are usually based on smartphones/mobile devices with position accuracies of 1 m or worse. These systems cannot warn of obstacles like mailboxes, road signs etc. reliably, since for this a sub-meter accuracy is needed. Further, Kalman Filters are used which cannot profit optimally from navigable maps. It would be desirable, if this geometric information could be used not only for the routing, but also to enhance and support the position solution. Therefore, the consortium consisting of the Graz University of Technology, the Vienna University of Technology, the company Strauß & Hollinger: GeoIT OG and Alice Geiger, a consultant for the interests of blind people, decided to develop the positioning component of a pedestrian navigation system for visually impaired people based on completely new approaches.
In general, within POScity three techniques will be combined to yield a position solution working more reliable and accurate than previous approaches:
GNSS single-frequency PPP based on code and phase measurements is planned to deliver positions from affordable GNSS equipment. In comparison to difference techniques, PPP uses model corrections instead of corrections on measurement level. Thus, the update rates are low, while precise positions can be obtained. In order to keep a high accuracy level, multi-GNSS, especially GALILEO, will be treated as well as the multipath behaviour of single signals.
The calculated position will be used in a Particle filter based on a navigable raster map. This map will contain specific information for visually impaired persons, as well as probabilities of location and direction. The uncertainty of the movement can be limited compared to a normal pedestrian, since a blind person mostly follows navigation aids/assistances along the path ways. Therefore, the GNSS solution can be combined with the map to get an improved user position. In this way, all information can be integrated to yield an optimum solution.
The developed positioning module can later on serve as basis for future pedestrian navigation systems for visually impaired persons or other special user groups asking for special needs.
This project was funded by the Austrian Promotion Agency (FFG) within the Austrian Space Applications Programme (ASAP).
Hafner, P.; Huber, K.; Moder, T.; Hollinger, G.; Strauß, C.:
Development of a Positioning Tool for the Navigation of Visually Impaired People - in: International Technical Meeting of the Satellite Division of the Institute of Navigation (ION GNSS+). Tampa - Florida, 08.09.2014-12.09.2014
Moder, T.; Hafner, P.; Wieser, M.:
Indoor Positioning for Visually Impaired People Based on Smartphones - in: Computers Helping People with Special Needs . Paris, 09.07.2014-11.07.2014