Three-dimensional thermography mapping for mobile rescue robots

In urban search and rescue situations, a 3D map obtained using a 3Drange sensor mounted on a rescue robot is very useful in determining a rescue crew's strategy. Furthermore, thermal images captured by an infrared camera enable rescue workers to effectively locate victims. The objective of this study is to develop a 3D thermography mapping system using a 3D map and thermal images; this system is to be mounted on a tele-operated (or autonomous) mobile rescue robot. The proposed system enables the operator to understand the shape and temperature of the disaster environment at a glance. To realize the proposed system, we developed a 3Dlaser scanner comprising a 2D laser scanner, DC motor, and rotary electrical connector. We used a conventional infrared camera to capture thermal images. To develop a 3D thermography map, we integrated the thermal images and the 3D range data using a geometric method. Furthermore, to enable fast exploration, we propose a method for continuous thermography mapping while the robot is in motion. This method can be realized by synchronizing the robot's position and orientation with the obtained sensing data. The performance of the system was experimentally evaluated in real-world conditions. In addition, we extended the proposed method by introducing an improved iterative closest point (ICP) scan matching algorithm called thermo-ICP, which uses temperature information. In this paper, we report development of (1) a 3D thermography mapping system and (2) a scan matching method using temperature information.