Design And Implementation Of Indoor Positioning System Based On Inertial Sensor

With the rapid development of information technology,location-based map services play a very important role in people's life and become an indispensable part of weekday travel.The technology of outdoor positioning has become more and more mature and has been used in people's daily life.But the technology of indoor positioning is still vacant.In recent years,there are many methods of indoor positioning,such as the indoor positioning method based on Geo-magnetic,the indoor positioning method based on WIFI,the indoor positioning method based on the inertial sensors,the indoor positioning method based on short-range wireless communication and so on.But each technology has its own advantages and disadvantages.The topic of this paper is the indoor positioning system of the telemedicine project,it's constructed by Jilin province and Jilin University.The project is the map service application based on indoor map and indoor positioning technology to provide the best path for users in large buildings.It lays the foundation for indoor navigation.The target users of the indoor positioning system are the patients of the hospitals.The cost of using the system should not be high.Therefore,this paper selects the technology of indoor positioning based on inertial sensor.It uses the inertial sensor integrated by the mobile terminal to estimate the direction and speed of the user.One of the biggest advantages is that the cost is low.It's not necessary to deploy the device in the scene and know the indoor environment in advance.Otherwise,this stability of it is high.Because it only needs to use the parameters of the inertial sensor,which are not affected by the external environment and other factors.This paper studies and analyzes the key technologies of indoor positioning system,then proposed the problems existing in technologies of indoor positioning and explains the solutions of this paper.It designs and implements a multi-mode,low-cost and highavailability indoor inertial positioning system based on the highly popular mobile terminals.The multi-mode means that the users' mobile devices can be positioned regardless of the holding mode.The low-cost means that it doesn't depend on external environment does not need to deploy any additional devices.The high availability means that the user only need to use the built-in sensors in mobile terminals to estimate position.Firstly,this paper designs the indoor inertial positioning system.The working principle is the algorithm of pedestrian dead reckoning.The inertial sensor built in the mobile terminal is used to collect the user's data.By processing and analyzing the data of the acceleration sensor,gyroscope and direction sensor,the number of steps,the step size and the moving direction of the user are obtained.Therefore,the user's real-time position coordinates are updated,and the user is tracked and positioned.Designed from the software level architecture,it can be divided into data access layer,business logic layer and interface layer.The system module is divided,which can be divided into data acquisition module,inertial positioning module,display module,and system control module from the functional point of view.Secondly,the indoor inertial positioning is designed in detail.By designing Butterworth low-pass filtering algorithm and Kalman filtering algorithm to process the inertial sensor data.The step number algorithm based on accelerometer and gyroscope is designed.The user's mobile terminal can accurately calculate the step numbers no matter what posture it is in.A step size algorithm based on acceleration sensor data is designed and a moving direction algorithm based on combination of direction sensor and gyroscope is designed.And use the data of the acceleration sensor to calculate the walking height.Finally,the key modules of the indoor inertial positioning system are implemented on the Android platform.The data acquisition and processing module of the system is implemented,and the step number calculation,step size calculation and moving direction algorithm in the positioning system are implemented.The overall operation of the system is also tested.