High resolution maps from wide angle sonar

TLDR

A sonar range reading gives information about empty and occupied volumes within a 30‑degree cone in front of the sensor. The study describes using multiple wide‑angle sonar range measurements to map the surroundings of an autonomous mobile robot. The method models sonar readings as probability profiles on a rasterized map and integrates multiple measurements from different viewpoints to reinforce empty volumes and condense occupied areas. Adding more readings improves map definition, producing probable occupied, unoccupied, and unknown regions; the method handles clutter and supports motion planning and landmark recognition, as demonstrated on the Neptune robot at CMU.

Abstract

We describe the use of multiple wide-angle sonar range measurements to map the surroundings of an autonomous mobile robot. A sonar range reading provides information concerning empty and occupied volumes in a cone (subtending 30 degrees in our case) in front of the sensor. The reading is modelled as probability profiles projected onto a rasterized map, where somewhere occupied and everywhere empty areas are represented. Range measurements from multiple points of view (taken from multiple sensors on the robot, and from the same sensors after robot moves) are systematically integrated in the map. Overlapping empty volumes re-inforce each other, and serve to condense the range of occupied volumes. The map definition improves as more readings are added. The final map shows regions probably occupied, probably unoccupied, and unknown areas. The method deals effectively with clutter, and can be used for motion planning and for extended landmark recognition. This system has been tested on the Neptune mobile robot at CMU.