Research On Indoor Matching Positioning Technology Based On Geomagnetic Field Information

With the rapid development of mobile Internet and Internet of Things,the focus of people’s activity places has gradually shifted from outdoor to indoor.Positioning signals suitable for outdoor satellites such as GPS and Beidou are difficult to penetrate the thick walls built by reinforced concrete and cannot provide accurate location services for people in the indoor environment.Facing the huge indoor positioning market and the growing demand for indoor positioning accuracy,researchers have put forward different types of indoor positioning technology,but it is difficult to balance the relationship between accuracy,stability and cost.As the basic physical attribute of the earth,the geomagnetic field has the characteristics of stability and persistence,which makes the geomagnetic field data become a reliable positioning reference source.According to the positioning accuracy requirements in the indoor complex environment,this paper uses the geomagnetic field to conduct the indoor matching and positioning.The work content is mainly studied from the following aspects:(1)The basic characteristic information of geomagnetic field is analyzed.By recording the changes in magnetic field data in time and space.Explore the stability of the geomagnetic field at the same location at different times and the differentiation of different locations at the same time.The feasibility of using geomagnetic field data as a positioning reference.(2)A fusion filtering method based on wavelet and Kalman is designed.Statistical data distribution characteristics are obtained after attitude correction processing of magnetic field data,and refined processing is performed for magnetic field information conforming to Gaussian distribution;By comparing different denoising scales,the mean and variance of noise were obtained by wavelet analysis,and the magnetic field data of fusion filtering was obtained by Kalman filtering equation.By comparing the mean square error,signal to noise ratio,and other indicators before and after filtering,it is determined that the fusion filtering method has a better noise reduction effect.(3)Different methods of constructing geomagnetic fingerprint images were analyzed.Establish different types of isoline geomagnetic fingerprints based on actual geomagnetic data,compare the deviation value,standard deviation,and other indicators before and after interpolation,and determine the scientificity of using Kriging interpolation method;A reconstruction method of geomagnetic fingerprint image is designed.Aiming at the abnormal magnetic field data in the location area,the abnormal data area is determined by correlation criteria,and the collected magnetic field data is weighted and fused to obtain the magnetic field information required for reconstruction.The experimental results show that the average positioning accuracy of the indoor positioning system in a 150m~2 area is 0.93m,and the matching accuracy is 89%,which can meet the basic requirements of indoor positioning.