By the Telocate members new approaches have been developed in the context of their research at the university making it possible to get rid of initial manual measurement of reference positions when locating with radio or (ultra-) sound signals, known as ToA/TDoA localization. Using self-calibration the reference positions are calculated automatically during system operation from the collected data without the user having to take care of it. In this way, self-calibrating TDoA/ToA algorithms save considerable installation effort of a localization system.
To demonstrate the practical feasibility of self-calibration the founding members of Telocate have developed an ultrasound system capable to locate a mobile station accurately up to 5 cm, without the need to specify prior reference positions of receivers. Self-calibration will be used commercially in the Telocate ASSIST smartphone localization system for the first time.
The following videos demonstrate the use of self-calibration on a remote controlled model car.
Particle Filtering: Tracking of a continuously moving ultrasonic transmitter, based on particle filtering of TDoA signals. By probabilistic modeling of the transmitter and receiver high reliability of the receiver initialization, as well as an accurate estimate of the transmitter position is achieved.
Cone Alignment: Pursuit of an ultrasonic transmitter using TDoA signals. The transmitter is mounted on a remote controlled car, which runs on an arbitrary path. The positions of the receivers are initially unknown. The Cone Alignment algorithm, an iterative spring-mass simulation predicts both the receiver positions (green), as well as the position of the ultrasonic transmitter (red).
For the interested reader more information is found in the publications of the team members of Telocate:
- Johannes Wendeberg, Fabian Höflinger, Christian Schindelhauer, and Leonhard Reindl. Calibration-Free TDOA Self-Localization. Journal of Location Based Services, 2013. (, )
- Johannes Wendeberg, Jörg Müller, Christian Schindelhauer, and Wolfram Burgard. Robust Tracking of a Mobile Beacon using Time Differences of Arrival with Simultaneous Calibration of Receiver Positions. In Proceedings of 2012 International Conference on Indoor Positioning and Indoor Navigation (IPIN), 2012. (, )
- Johannes Wendeberg. Calibration-Free Localization using Time Differences of Arrival. PhD thesis, University of Freiburg, 2013. ( )