Integration WLAN And INS Indoor Positioning System

With the rapid development of information technology,people's demand for location-based services is getting higher and higher.People are no longer satisfied with outdoor positioning represented by GPS,but put forward higher requirements for indoor positioning.In the field of indoor positioning technologies,Wi-Fi-based indoor positioning technology and inertial sensor-based indoor positioning technology have always been favored by researchers.In recent years,Wi-Fi signal coverage has grown exponentially,which has further reduced the cost of Wi-Fi-based positioning technology.Inertial sensor-based positioning technology has the advantages of strong scalability and real-time tracking of target positions.Nowadays,smart phones are very popular and most smartphones have embedded a variety of sensors,making inertial sensor-based positioning technology more convenient,less costly,easier to promote,and get more and more attention.The conventional Wi-Fi-based indoor positioning technology is susceptible to complex indoor environments,even the walking of indoor pedestrians may block the signals,making the collected data inaccurate and affecting the positioning accuracy.The conventional inertial sensor-based indoor positioning technology obtains the relative position coordinates,which will cause the error accumulation,so that it is difficult to achieve the desired positioning accuracy.In view that indoor positioning has the characteristics of complex environment and high precision requirements,this paper studies an indoor positioning scheme that integrates WLAN and inertial sensors.The main research and design contents are:(1).First,the path loss model and the probability distribution model are analyzed and designed to determine the algorithm parameters and flow charts.Then the path loss model and the probability distribution model in the Wi-Fi positioning technology are implemented by the intelligent terminal combined with the application server service.Finally,the two models were simulated and tested.The Wi-Fi positioning accuracy and robustness based on the probability distribution model were obviously higher than the path loss model with the increase of signal source and data volume.(2).The inertial sensor positioning technology differs from the previous method in which the system only uses the simple integration of the acceleration twice to obtain the step size.This paper analyzes the actually measured waveforms of the acceleration sensor and proposes the idea of using the number of crests in the Z direction to calculate the step,and through the actual The number of steps is compared with the estimated number of steps,which verifies the reliability of the idea of this article and further determines the step size.It is also found through the test that the X-direction acceleration value can reflect the deviation angle of the target to be measured.Therefore,combined with the step length and dead-end deflection angle,the pedestrian position deduction algorithm can be used to predict the position of the positioning target and reduce the cumulative error.(3).On the application server side,combining Wi-Fi positioning absolute position and inertial sensor positioning relative position two parts of information,the use of extended Kalman filtering algorithm for fusion,to get more accurate indoor positioning information than the maximum positioning sensor alone The error is reduced by 48.7%.This paper ultimately a set of Wi-Fi based location technology and inertial positioning sensor fusion,static accuracy of 1m,dynamic trajectory tracking accuracy indoor location system of 2m.