Research On Smartphone Sensor-Based Algorithm For Forest-Pedestrian Location

Aiming at the problems of the lack of satellite signals and the difficulty in locating in the forest area,a smartphone sensor-based algorithm for forest-pedestrian location(FPL)was proposed in this paper,and developed an experimental platform system based on GeoGIS for FPL algorithm for Android platform.Finally,experiments of the FPL algorithm and other algorithms were carried out at the Beijing Jiufeng National Forest Park,using the Xiaomi Note.The FPL algorithm was an improved algorithm based on the PDR algorithm.Firstly,the EKF and KF fusion algorithms was used to fuse the outputs of magnetometer,accelerometer and gyroscope in turn to improve the azimuth measurement accuracy.Secondly,the S-G filter was used to process the azimuth measurements to improve the accuracy of azimuth estimation in PDR algorithm.Subsequently,the KNN algorithm was introduced to estimate the step length,then the problem of fitting the explicit step function was divided into a "lazy learning" problem.Finally,use the differential barometric altimetry method to calculate the pedestrian elevation,so as to obtain the three-dimensional location information.The experimental result proved the algorithm could improve the accuracy of azimuth and step length,and could increase the accurate elevation information.The overall error was controlled within 5%,within the forest area,which could meet the requirement of locating in the forest area where the GNSS signal intermittent.