Precise self-calibration of ultrasound based indoor localization systems

Several ultrasound based localization systems consist of environmental anchor nodes, and mobile nodes, which estimate their own position by using a static infrastructure. For the location process, every anchor has to know its position. In most approaches, the location of all anchors has to be determined a priori manually. This procedure is time consuming and fault-prone. In this paper, we present Distribute & Erase and Explorer, two self-calibration methods for ultrasound based localization systems. The first uses a set of three pre-calibrated anchors to explore the whole localization system whereas the second refines the anchors´ positions progressively. Both of our approaches require no additional hardware besides ultrasound receivers or transmitters, and radio transceivers, which have to be already available for the WSN based localization system.