Design And Implementation Of Indoor Positioning System Based On UWB

With the accuracy improvement and cost reduction of positioning technology,the situational application based on positioning is also integrated into all aspects of daily life,such as the care and positioning of key objects,the mobile positioning of important materials and goods in warehouse,the target positioning of large shopping malls,etc.,which can be divided into two categories: outdoor basic positioning and indoor highprecision positioning.Indoor positioning refers to positioning in a closed and semi-enclosed limited space,with a narrow range and generally covered by walls and other obstructions.Traditional outdoor positioning technology is blocked by obstructions during the propagation process,causing attenuation and scattering of electromagnetic signals such as satellite base stations,resulting in increased positioning errors and unable to meet high-precision positioning requirements.Therefore,the mainstream indoor positioning technology mainly uses wireless communication,base station positioning,infrared positioning,etc.,to send broadcast signals through indoor fixed equipment,receive feedback signals on the target object to be positioned to obtain the distance or angle,combined with signal attenuation models or mathematical methods Calculate the coordinates of the positioning object.So far,among high-precision indoor positioning technologies,the most widely used is Ultra wide band(UWB)technology.Ultra wide band technology is based on short-range wireless communication technology,which has the advantages of fast transmission rate,strong penetration,low power consumption,and strong anti-multipath interference ability,and is especially suitable for indoor highprecision positioning.This paper is based on the requirements of the “Smart Nursing” project of an institution in Guizhou Province,based on the arrival time algorithm and ultra-wideband technology,combined with embedded system technology to design and implement an indoor high-precision positioning system.The application scenario of this system has a positioning accuracy of less than 20 cm,and can realize real-time positioning of mobile tags in a closed and semi-closed coverage area.Firstly,this paper introduces the current indoor positioning technology.By comparing the cost,accuracy,range,security and other factors,UWB technology is finally selected as the research object.Then,the characteristics and advantages and disadvantages of mainstream wireless communication positioning algorithms are analyzed and discussed,and the Time of Arrival(TOA)positioning algorithm with high positioning accuracy and easy implementation is determined for further study.According to the characteristics of TOA algorithm which requires hardware clock synchronization,this paper analyzes the error of one-way ranging,two-way ranging and double side two way ranging algorithms.Through derivation,it is proved that the algorithm with the minimum error can solve the problem of base station label clock synchronization from the software level,and double side two way ranging algorithm is selected.Aiming at the problem of heavy tag load caused by double side two way ranging,this paper proposes an improved double side two way ranging algorithm to hand over the data processing and data transmission tasks to the base station,reducing the tag load and supporting multi-tag positioning;on this basis,this paper makes the overall system design,hardware design and software design of the UWB positioning system,including the selection of DWM1000 module and STM32 chip to design the main control module of hardware,UWB signal transceiver module,etc.,designs the hardware PCB to integrate the above modules,and then designs and develops the embedded program and upper computer software to realize the indoor positioning system.Finally,the UWB indoor positioning system studied and designed in this paper is applied to the intelligent nursing system of key objects in a prefecture level city of Guizhou Province to achieve the precision positioning of 20 cm level activities of key objects and meet the actual needs.