HALO4: Horizontal Angle Localization and Orientation System with 4 Receivers and Based on Ultrasounds

Abstract

This paper presents a low cost ultrasonic localization and orientation system based on the DTOA (Differential Time Of Arrival) technique. The proposed system consists in deploying any number of autonomous nodes at the floor of a room and place some transmitters at the ceiling. Each node shall have four ultrasonic receivers to obtain the basic measures for the localization and orientation systems, and the coverage area of the system is defined by any region covered by at least three transmitters. The localization system is based on an estimation process of the horizontal angle of the node with respect to the transmitters. This implementation allows deploying the transmitters at different heights and ignores the error introduced by an incorrect estimation of the ultrasonic signal speed. The computational effort of the proposed system is greater than other ALO (Angle Localization and Orientation) systems, needing a minimization process to obtain the localization results, but it is smaller than in other typical techniques, like those based on the intersection of hyperboloids.