Design And Implementation Of High-precision Positioning Of Mobile Terminal

In recent years,with the development of mobile Internet technology and the intelligentization of mobile terminals,Accurate geographic location of users in complex environments needs to be timely acquired by location based services(LBS)in the mobile Internet,in order to push accurate and reasonable services to users.To meet the urgent needs of obtaining timely and accurate location information,various positioning technologies have been proposed.The differential positioning technology in satellite navigation system can provide accurate position information when the satellite signal is unshielded,but under high dynamic circumstances,such as the shelter of mountains,tall buildings and trees.,the satellite signal is weaken or even lost,the ability of mobile terminal to capture and track satellite signals is declining,which makes it impossible to locate.Pedestrian Dead Reckoning(PDR)positioning uses inertial sensor elements to achieve positioning function.The positioning is not easily affected by external environment.It has good autonomy and continuity.It can provide accurate location information in a short time.However,the positioning results have accumulated errors over time and can not provide effective location information for a long time.Therefore,in view of the advantages and disadvantages of differential positioning and PDR positioning,this paper proposes a integrated positioning method of differential positioning and PDR positioning.Differential positioning uses open source package to achieve differential positioning function in Android mobile terminal.In PDR positioning,three parts,step detection,step length estimation and heading estimation,are studied in detail,and each part is optimized.The dynamic threshold peak detection algorithm is used in step detection,which makes the pedestrian step statistics more accurate;the non-linear step model is used in step estimation,which can meet the required accuracy requirements;and the multi-sensor fusion Madgwick algorithm is used in heading estimation,which improves the accuracy of heading information compared with the direct use of direction sensors.The extended Kalman filter(EKF)algorithm is used to fuse differential positioning and PDR positioning,which can reduce the cumulative error of PDR positioning.PDR positioning can compensate for the discontinuity of output fluctuation of differential positioning in dynamic environment.Finally,the framework of the integrated positioning system is designed,and the application of the differential positioning and PDR positioning integrated positioning system in mobile terminal is realized by using Android development platform,and the validation and evaluation are carried out.The results show that the integrated positioning system has significant advantages over single differential positioning and PDR positioning.