Exploration of a group of mobile robots for multiple radiation sources estimation

In this work, we consider the estimation problem of multiple unknown sources of radiation with measurement uncertainty by using multi-robot systems in a geometric environment. We proposed the scheme for intensity estimation method of multiple radioactive sources using the particle filter with disperse resampling algorithm and source separation strategy. A team of mobile robots will estimate the source by moving toward the estimated location. However, in a low intensity area, the estimated location becomes unstable. Thus, an exploration algorithm must be utilized and the exploration cost must be minimized because the exploration time may be limited. We propose the exploration method using frontier-based exploration which involves the target point selection algorithm by considering the minimum distance from a robot to an unexplored region, and the increasing gradient direction. In addition, area pruning algorithm is used to further decrease the exploration cost by estimating the low intensity area then ignore them. The proposed method has been verified by the simulation using MATLAB. The proposed method can greatly reduce the exploration cost compared to the conventional method and increase the accuracy of multiple sources intensity estimation.