Estimating position relation between two pedestrians using mobile phones

Abstract

In a complex indoor environment such as a huge station in an urban area, sometimes the direction and distance relative to another person are more important for pedestrians than their absolute positions, e.g. to search for a lost child. We define this information as the position relation. Our goal is to develop a position relation estimation method on a mobile phone with built-in motion sensors. In literature, methods of cooperative navigation using two pedestrians' positions estimated by pedestrian dead reckoning and a range sensor have been proposed. However, these methods cannot be applied to a mobile phone because pedestrian dead reckoning does not work well when a mobile phone is in a bag, and because there is no range sensor in a phone. In fact, no Bluetooth is reliable as a substitute range sensor. This paper proposes another approach to estimate the position relation of pedestrians. Our method finds the timing when two pedestrians are in close proximity to each other and walk together by using Bluetooth as a proximity sensor and corrects the parameters of position updates dynamically, even if absolute positions are unknown. The algorithm and evaluation results are presented in this paper. © 2012 Springer-Verlag Berlin Heidelberg.