In this paper we present a new technique for improving the azimuth
resolution of ultrasonic range sensors frequently used with mobile
robots. This improvement is achieved without a significant increase in
the latency, or processing delay, of the system. Our approach
decreases the azimuth uncertainty of a sensor reading by eliminating
portions of the reading that are contradicted by subsequent
readings. Our idea bears resemblance to space carving as used by the
vision community, where a ray of light is used to define the
boundaries of an obstacle. A sonar model similar to that commonly
utilized by occupancy grids is used. Our method, termed arc carving,
can be used to produce maps that are both accurate and with low enough
latency for robust mobile robot navigation. Experimental results
verify this approach over spaces as large as 5000 square meters.