Autonomous indoor mobile robots are gaining increasing popularity for the shared...

Autonomous indoor mobile robots are gaining increasing popularity for the shared use in military and civil applications. Recently aerial or ground robots of various shapes and sizes have been developed for quick detection and observation of circumstances in calamity environments such as indoor fire spots [1, 2]. In an indoor environment, however, weak reception of GPS signals has posed additional challenges to the operation of the robots. Therefore less expensive self-localization with unaided external sensors is one of the most important problems in popularizing indoor mobile robot products.