Abstract

This paper describes a, met;hod by which range data from a sonar or other type of rangefinder can be used to determine the 2-dmensional position and orienl, ation of a mobile robot inside a room. The plan of tim room is modeled as a list. of segments indicating the positions of walls. The method works by extracting straight segments from the range data and examining a,]l hypolheses about pairings between the segments and xva]ts in the model of the room. lnconsisl,ent pairings are discarded efficiently by using local constraints based on distances between walls, angles between wall,. and ranges belween walls along their normal vectors. These consl, raints at'(' used 1o ob a.i a small sel. of' possible positions, which is f'urther pruned t_sing a test for physical consistency. The approach is extremely tolerant of noise and clut. t, er. Transient objects su(' as furniture and people need not be included in the roorn model, and very noisy, low-resolution sensors can be used. The algorithm's performance is demonstrated using a Polaroid Ultrasonic Rangefinder, which is a 1ow-resolut'ion, high-noise sensor.

Citations