Indoor And Outdoor Seamless Positioning Based On GPS/DR/WiFi

Ancient Sinan used as recognition direction,now satellite used as navigation and positioning,the search for location information by humans has never stopped.From a simple magnetic needle to a sophisticated receiver,positioning technology becomes more and more advanced,positioning accuracy is getting higher and higher.At present,satellite positioning systems such as GPS have fully matured in outdoor environments.Pocket-sized GPS chips are embedded in mobile phones and other carriers to meet users’ daily positioning needs.For the indoor environment where the satellite signals cannot reach,the “last mile” of navigation and positioning has been achieved through communication technologies such as WiFi,Bluetooth,and radio frequency identification.However,the convergence and switching technologies of indoor and outdoor different positioning methods,as well as the commonly used indoor positioning technology need to be carried out in the early stage of equipment layout and the establishment of data database and other issues,which can not meet the current indoor and outdoor seamless positioning intelligent development requirements.Therefore,in this paper,smart phones are used as carriers to study intelligent seamless positioning technology,and GPS/DR/WiFi fusion is proposed for indoor and outdoor seamless positioning.The method automatically switches the positioning method according to the signal type at the junction between indoor and outdoor,and can also automatically calculate the coordinates of the indoor WiFi access point,so as to achieve intelligent indoor and outdoor seamless positioning.The specific research content of the paper is as follows:（1）This paper analyzes the research status,advantages and disadvantages of GPS technology,WiFi positioning technology,DR technology and commonly used indoor and outdoor seamless positioning technology.According to the complementary characteristics of the advantages and disadvantages of the GPS technology and the DR technology,the extended Kalman filter algorithm is used to fuse the two to improve the outdoor positioning accuracy and enhance the availability and flexibility of the positioning of the satellite signal when obstructed.In this algorithm,the steprate information is obtained by means of mean value cross-detection using dead reckoning acceleration data and the step size is determined by the linear step size estimation model.The gyro data obtains the heading angle change value,and the initial heading angle is obtained by using the geomagnetic data in the initial stage of positioning.The step length and the change of the heading angle are time-aligned with the GPS data frequency,and the Kalman filter algorithm is integrated with the GPS data.Experiments show that the combined positioning of GPS/DR can suppress the DR divergence for a long time and improve the positioning accuracy in the outdoor environment.（2）The paper proposes an algorithm for automatic calculation of indoor network access point coordinates based on L₁ method（M estimation）.The algorithm uses the coordinate information of the indoor diplomatic community and the RSSI data of the access point to inversely calculate the coordinates of the indoor access point and reduce the preparatory work for indoor positioning.Experiments show that the coordinate data obtained by the algorithm is highly accurate.Using the calculated indoor access point coordinates,a DR-based WiFi-assisted positioning model is used in the indoor environment to achieve high-precision DR/WiFi indoor integrated navigation and positioning.（3）In order to obtain the raw data of the GPS module,sensor module,and WiFi module in the smart phone,the Collector software was written in Java language in the Eclipse development environment,and the raw data was automatically obtained and stored.（4）This paper has developed a technical solution for seamless positioning between indoor and outdoor based on GPS/DR/WiFi,and determined different positioning technology switching strategies.Based on the original data acquired by Collector software,seamless indoor and outdoor navigation positioning is realized.Experiments show that this scheme achieves seamless connection between outdoor environment and indoor environment without the need to measure the indoor access point coordinates,and the accuracy is good.It provides theoretical and practical basis for the intelligent development of seamless navigation and positioning technology.