Remote Monitoring System Based On BDS/GPS And Indoor Positioning Fusion

As communication technology advancing from 4G to 5G era,people's demand for location services is increasing and accuracy requirements are getting higher and higher.At present,the location services that on the market are usually limited to outdoor areas and lack of specific objects.Both indoor and outdoor location are needed.These specific objects refer to those needed specific remotely monitor,such as children,the elderly,and people with amnesia who cannot take care of themselves,as well as valuables in jewelry stores and cultural relics in museum collections,or important scientific instruments and materials in the laboratory,etc.Therefore,this paper has designed a remote monitoring system based on the integration of BeiDou Navigation Satellite System(BDS)/GPS and indoor positioning,aiming to be able to select and switch a variety of positioning technologies,which can achieve the monitoring function during the user's dynamic movement.The system mainly combines outdoor positioning technology based on BDS/GPS dual-mode positioning and indoor location fingerprint technology based on Bluetooth Received Signal Strength(RSS),and uses counting and threshold mechanisms to switch between different positioning technologies during the movement in indoor and outdoor scenes,the position of the positioning terminal can be continuously calculated to achieve monitoring of the monitored object.In order to make the system effective,this article has conducted the following research:(1)Aiming at the problem that the location fingerprint indoor positioning algorithm based on received signal strength(RSS)has poor positioning accuracy,a mean-linkage(ML)hierarchical clustering and adaptive weighted K nearest neighbor(WKNN)positioning algorithm is proposed.Firstly,the Bluetooth signal strength is collected at the set reference point to construct an offline fingerprint database.Then,using ML hierarchical clustering method,all reference points are divided into n categories according to the similarity between them,and the reference point with less similarity is filtered out.Finally,according to the similarity of the signal distance between the point to be located and the reference point,the standard deviation of the distance difference is calculated to adaptively determine the K value and conduct position estimation.The experimental results show that the average positioning error of the proposed algorithm is 30.0% and 18.0% lower than that of WKNN and EWKNN,and the positioning timeis 19.2% and 28.4% lower than that of WKNN and EWKNN,respectively.The algorithm is applied to indoor object positioning,which can simultaneously improve positioning accuracy and real-time positioning.(2)In order to achieve fusion positioning in indoor and outdoor environments,and design a remote monitoring system for personal users,This system adopts the indoor and outdoor fusion location algorithm based on the combination of dual threshold and mobile terminal computing.During the indoor and outdoor positioning process,due to the overlap between the Bluetooth signal coverage area and the BDS/GPS signal coverage area,the switching of positioning technology in this overlapping area will cause a ping-pong effect,that is,satellite positioning and Bluetooth positioning switching will happen repeatedly.In order to solve these problems,the system adopts a double threshold and multi threshold alpha count switching algorithm in indoor and outdoor location switching.In the switching algorithm,multiple Bluetooth thresholds AP(access point)and trigger threshold are added to ensure the stability of the switching algorithm.Through the handover algorithm,indoor location and outdoor location are integrated.At the same time,the indoor and outdoor location calculation is applied to the mobile terminal.The experimental results show that the fusion location algorithm used in this system can prevent the wrong switch of different location technologies,and it is suitable for mobile terminals.(3)The overall framework of the system is designed to achieve the function of each module.The remote monitoring system is mainly composed of a main control module,a GNSS module,a GSM module,a Bluetooth signal receiving module and an Android mobile terminal composition.The main control module mainly controls latitude and longitude information processing,receiving and processing Bluetooth signals and indoor and outdoor location switching judgment,as well as SMS sending;the GNSS module mainly controls the positioning terminal outdoor location information collection function;the GSM module mainly completes outdoor latitude and longitude information or indoor Bluetooth signals Remote transmission of strength information;the Bluetooth signal receiving module mainly receives the signal strength of the Bluetooth iBeacon device for data collection;the Android mobile terminal is mainly responsible for capturing the SMS of positioning information and identifying the location source of the captured SMS.If the mobile terminal captures the indoor Bluetooth signal strength SMS,the indoor location algorithm is used to calculate the indoor location and display the location in the indoor map.If the outdoor latitude and longitude information is received,the latitude and longitude coordinates are calculated and processed in the mobile terminal,and the location of the positioning terminal will be displayed in the outdoor map.Complete the remote positioning monitoring of the positioning terminal through the mobile terminal.(4)The model of the control chip STM32 and the device type of each module aredetermined by the system functional requirements.The function program of each module of the positioning terminal is designed and implemented on the Keil uVision5 software through C language.Using the JAVA programming language to accomplish the monitoring software based on the Android system client on the Eclipse software development platform.The various modules of the remote monitoring system were debugged and the overall joint debugging was carried out.The results show that the system accomplish the basic functions of remote monitoring and seamless indoor and outdoor positioning.