Collaborative positioning for emergency rescuers based on INS, GPS and ZigBee

Abstract

Multi-person cooperative positioning is one of the main techniques to improve the success rate of search and rescue. Nevertheless, current integrated positioning solutions for ZigBee and inertial navigation system (INS) are insufficiently versatile and commonly necessitate pre-existing infrastructure within the area. In this study, it is not necessary to install ZigBee positioning anchors in the environment in advance, and all positioning devices were mounted on rescuers, in contrast to previous positioning methods. First, an improved time difference of arrival (TDOA) method is proposed, which weights the position coordinates to minimize positioning errors. Then, the position data of the commander and the rescuers are substituted into the hyperbolic equations of the improved TDOA method, and the initial position of the rescuers is solved by Taylor method. Finally, based on the initial position, an improved Extended Kalman filter (EKF) position update technology is proposed, which uses ZigBee positioning system to monitor the east and north position of rescuers, and uses barometers to measure the altitude of rescuers. The magnetometers are used to limit the heading angle of the rescuers, so as to realize the high-precision 3D positioning of the emergency rescuers in the harsh environment. In this paper, three different scenarios are used to verify the effectiveness of the proposed method. The experimental results demonstrate that, when compared to the inertial positioning method, the traditional TDOA method, and the cooperative positioning method based on the relative ranging constraints of UWB and INS, respectively, the average positioning accuracy of the proposed method is 68.58%, 48.71%, and 13.59% higher.