Research On Indoor Positioning System For Mobile Terminal Based On PDR And Geomagnetism

With the widespread use of mobile devices and mobile communication technology,mobile Internet has been booming,Location-based services(LBS)are playing an increasingly important role in life.People's demand for positioning technology has extend from outdoor to indoor.However,traditional statellite navigation and positioning technology can not meet the needs of indoor location because the signal is blocked by buildings.Indoor positioning technology has become a research hotspot at home and abroad,and a variety of indoor positioning technologies coexist,among which WiFi,Buletooth,Ultra-Wide-Band and other wireless network technologies all rely on infrastructure.Pedestrian dead reckoning technology using smart phone motion sensors has the advantages of high positioning accuracy in a short time and no need for infrastructure.In addition,geomagnetic signals have great potential in positioning due to their good stability and seamless indoor coverage.In this paper,the mobile phone is used as a positioning terminal,and the accelerometer,gyroscope and magnetometer of the mobile phone are fully utilized.Initial verification of the positioning system.The research content of this article mainly includes:(1)Improve the adaptability of pedestrian dead reckoning technology.In view of the problem that the traditional mobile phone PDR algorithm is limited by the way the mobile phone is carried,the paper proposes a PDR algorithm based on pattern recognition.Using the acceleration signal of the mobile phone,the K nearest neighbor algorithm is used through the process of "data collection,data processing,feature extraction,classification recognition".Recognized the usage mode of the mobile phone and based on the pitch angle detection algorithm based on pitch angle.The feasibility of the algorithm is verified through experiments.(2)Aiming at the mobile phone geomagnetic matching positioning,the paper describes the method of continuous geomagnetic acquisition based on PDR.For sparse geomagnetic data,the effects of inverse distance weighting,cubic spline interpolation and Kriging interpolation to construct the geomagnetic reference map are compared.This paper introduces the method of obtaining geomagnetic data by using Android mobile phone,analyzes the difference of indoor geomagnetic signals by using two indicators of geomagnetic variance and roughness.(3)Proposed geomagnetic positioning and PDR fusion positioning strategy.Aiming at the characteristics of PDR positioning error accumulation and the fuzzy point problem of global geomagnetic matching,a fusion method based on particle filter is proposed in this paper,which effectively improves the stability of the system and guarantees the positioning accuracy.Experiments show that the particle fusion positioning method can eliminate the PDR drift,and the average positioning accuracy reaches 1.38 m,and the positioning error reaches more than 80% within 1.5m.(4)Designed and implemented an indoor positioning system on the mobile phone.The article introduces the production of indoor maps,the selection of map engines,and the design of the system.Using Android Studio,the indoor map display and real-time indoor positioning system on the Android mobile phone are developed.