Mobile robot relocation from echolocation constraints

This paper presents a method for relocation of a mobile robot using sonar d ata. The process of determining the pose of a mobile robot with respect to a global reference frame in situations where no a priori estimate of the ro bot's location is available is cast as a problem of searching for correspon dences between measurements and an a priori map of the environment. A physi cally-based based sonar sensor model is used to characterize the geometric constraints provided by echolocation measurements of different types of obj ects. Individual range returns are used as data features in a constraint-ba sed search to determine the robot's position. A hypothesize and test techni que is employed in which positions of the robot are calculated from all pos sible combinations of two range returns that satisfy the measurement model. The algorithm determines the positions which provide the best match betwee n the range returns and the environment model. The performance of the appro ach is demonstrated using data both a single scanning Polaroid sonar and fr om a ring of Polaroid sonar sensors.