Search strategy of a mobile robot for radiation sources in an unknown environment

Searching radiation sources in a nuclear environment plays an important role in securing nuclear safety. In this paper, we present a search strategy of a mobile robot for radiation sources in an unknown environment. The proposed method enables a mobile robot to find radiation sources autonomously because it is harmless to expose the robot to an environment contaminated by radiation. Previous work employed a robot to find radiation sources with a given environmental map. Realistically, once a nuclear accident occurs, the environment would be partially destroyed. Thus, the purpose of this paper aims at navigating a mobile robot to radiation sources without a given environmental map. To achieve the goal, two sub-problems are discussed in this paper: (1) how does a mobile robot navigate itself to radiation sources without a map, and (2) how is the position and intensity of a radiation source estimated by a Geiger counter. For these two problems, an artificial potential field (APF) is adopted to navigate the robot to radiation sources and the direction and intensity of the attractive force in the APF is estimated by a particle filter. We provide a simulation validation of the proposed method which demonstrated good results to find the radiation sources without the map.