Research On Indoor Positioning Technology Based On Geomagnetic Field For Security Requirement

The magnetic field around the room is formed by the relative stability of the predictable Earth's magnetic field and the magnetic field generated by the surrounding ferromagnetic objects.Geomagnetic field has spatial difference and relative stability in time which could be used to identify geographic location.Geomagnetic navigation technology is a passive and autonomous positioning technology that can be widely used in underground mines,military anti-terrorism drills,prisons,and indoor rooms where safety and reliability requirements are strict.Recently,underground mine navigation is mainly based on non-autonomous radio technology positioning scheme and rely on power to transmit radio waves to achieve information transfer.When the power supply of underground mine is interrupted or the network is unstable,the positioning service function will be disturbed or even damaged.When disaster strikes,this kind of base station-type positioning system doesn't work anymore.Geomagnetic navigation technology does not require network or base station which can deal with critical situations better when a mine disaster occurs.The main work of this article is as follows:(1)This article analyzes the reference models of geomagnetic and indoor magnetic fields,according to the magnetic dipole model simulation simulates indoor magnetic field distribution,the number and the strength of dipoles were randomly generated based on a Possion and truncated distribution respectively;this paper analyzes the interference factors of indoor magnetic field and its interference removal algorithm,the magnetic north direction G is mainly decomposed from the indoor magnetic field R in which a disturbing magnetic field exists.(2)A geomagnetic reference map is established and the magnetic field data is tested.The grid of the test position is divided on the map,geomagnetic data is collected every 0.8 m(collect 30 data to calculate the average value),match the coordinate position in the matching area with the geomagnetic field strength.The Pedestrian Dead Reckoning(PDR)algorithm is introduced and the geomagnetic field aided PDR autonomous positioning scheme combined with geomagnetic particle filtering and pedestrian dead reckoning was presented.(3)An indoor positioning module is designed,which can achieve three-dimensional magnetic field data collection and pedestrian dead reckoning and estimate the coordinates of the target by introducing a particle filter to compare the real-time magnetic field data of the target carrier with the magnetic field data in the reference magnetic fingerprint library.Therefore,the cumulative error generated by the pedestrian dead reckoning algorithm is corrected.Compared with the individual pedestrian dead reckoning scheme,the experimental results show that the average positioning accuracy of geomagnetic field aided PDR autonomous positioning proposed in this paper has been improved about 0.4m.