1 Introduction
There are growing research activities for urban search and rescue (USAR) utilizing autonomous mobile robots [1], [2]. USAR aims to search for and rescue victims in disaster zones, especially those littered with debris from man-made objects such as collapsed buildings. Many aspects of the related robotics have been investigated [3] for movement over rough terrain [4], [5], localization and navigation with obstacle avoidance [6], [7], [8], sensor systems that react to human bodies [9], and so on.