A robust indoor positioning system using two-stage EKF SLAM for first responders in an emergency environment

A positioning method for a first responder in an indoor emergency environment is needed to strengthen a safety for rescue operation. In Korea, it is focused as one of the national agenda. Though many researches are done in this field, but they still have limitations of system preloading and a poor positioning accuracy depending on an arbitrary situation. This paper presents a robust indoor positioning system for the first responder in the scene of fire. The proposed positioning system consists of a monitoring station outside a building, portable access points (APs), and first responders. In the first place, the first responder measure distances to other first responders and portable APs in the hearable range, and calculates its relative position utilizing the simultaneous localization and mapping (SLAM) method implemented with the Extended Kalman Filter (EKF). In this process, the position information stored in the APs and first responders can serve as a map for the others. Then the initial position guess and distance measurements are delivered to the monitoring station via ad-hoc network by portable APs and first responders to correct position estimates of those in the whole system. The monitoring station also uses EKF SLAM method with all available position estimates and distance measurements. In this paper, the system configuration and positioning method are presented, and the simulation on the positioning of the portable APs and the first responders with respect to the monitoring station is carried out to certify the feasibility of the proposed system.