The LOPSI group uses ultrasonic technology for high accuracy positioning in small indoor areas. By measuring the time-of-flight (TOF) of ultrasonic signals propagating from several static beacons to a mobile node, its position can be computed by multilateration techniques, usually with an accuracy around 1 cm.
- Development of new ultrasonic transducers based on flexible ferroelectret materials (EMFi), in order to improve the system’s bandwidth and control the transducer’s directivity.
- Modulation and codification of ultrasonic signals with Code Division Multiple Access processing (CDMA) techniques, for simultaneous operation with multiple transducers and precise ranging; in essence, replicating with ultrasonic technology the main features of the GPS positioning system.
- Robust multilateration positioning in the presence of outliers in the time-of-flight measurements
- Autocalibration methods to determine the position of the network of beacons