Ultrasonic local positioning system for mobile robot navigation: From low to high level processing

This paper presents the different levels of signal processing applied to an extensive Ultrasonic Local Positioning System (ULPS) intended for mobile robot (MR) indoor navigation. The working area is covered using several single LPSs, each of them composed of a set of closely arranged ultrasonic beacons. Low-level signal processing deals with the simultaneous encoded emission of the beacons that compose each single LPS and the detection carried out in each ultrasonic receiver on board the MR, with the aim of determining Differences of Times of Flights (DoTFs) to be applied to a positioning algorithm. High-level signal processing takes into account the positions obtained with each single ULPS to reference them to a global coordinate system and to perform navigation tasks in which the typical cumulative errors of MR odometer are corrected. The whole system has been developed and tested within the LORIS project.