Indoor Localization Utilizing Tracking Scanners and Motion Sensors

In this paper, we propose a new method of highly-accurate mobile phone tracking using infrastructure-based laser-tracking sensors called laser-range scanners (LRS) and pedestrian DR (PDR) on the mobile phones. Each mobile phone continuously obtains readings from accelerometers and gyro sensors to detect moving distance and direction change (PDR information), while the phone user is accurately tracked anonymously by LRS from the infrastructure. Such PDR information, which forms a partial, relative trajectory in each time window, is sent to the infrastructure, and our system finds the best matched one in the set of anonymous (but accurate) laser-based trajectories with absolute coordinates. Then the matched trajectory is given to the identified mobile phone user so that he/she can utilize it as his/her accurate trajectory on the phone. PDR itself is likely to accumulate errors but by the support of LRS, such errors are eliminated in the laser-enabled region (e.g. A circle with a 30m radius by a single LRS). Even in the rest of the region, PDR may continue self-tracking, and such mutual complement works fine for phone tracking in the whole space. We have deployed 6 laser-range scanners and our PDR app on Android smartphones and conducted experiments. As a result, in almost all the cases the method could identify mobile phone users in laser-based trajectories.