Development of a laser range finder for three-dimensional map building in rubble

Abstract

In order to search and rescue victims in rubble effectively, a three-dimensional (3D) map of the rubble is required. As a part of the national project on rescue robot systems, we are investigating a method for constructing a 3D map of rubble by teleoperated mobile robots. In this paper, we developed a laser range finder for 3D map building in rubble. The developed range finder consists of a ring laser beam module and an omnivison camera. The ring laser beam is generated by using a conical mirror and it is radiated toward the interior wall of the rubble around a mobile robot on which the laser range finder is mounted. The ominivison camera with a hyperbolic mirror can capture the reflected image of the ring laser on the rubble. Based on the triangulation principle, cross-section range data is obtained. Continuing this measurement as the mobile robot moves inside the rubble, a 3D map is obtained. We constructed a geometric model of the laser range finder for error analysis and obtained an optimal dimension of the laser range finder. Based on this analysis, we actually prototyped a range finder. Experimental results show that the actual measurement errors are well matched to the theoretical values. Using the prototyped laser range finder, a 3D map of rubble was actually built with reasonable accuracy.