Arc carving: obtaining accurate, low latency maps from ultrasonic range sensors

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.