Design And Implementation Of Localization System For Indoor Parking Areas Based On UWB

Parking is a fundamental demand during car travel.With the increasing number of traffic volume,the parking space resource is becoming more and more intense.It's difficult for drivers to find a target parking space as parking lots are getting more and more complicated.While the GPS can help drivers find a target parking space efficiently outside,it's inefficient inside.Therefore,it's important to apply the indoor wireless localization technology to the indoor parking areas localization system..In an indoor parking lot,the speed of traffic is generally limited to 5km/h,namely no more than 1.39m/s.And the size of every parking space is usually about 5.5m X 2.5m.Thus,the indoor parking areas localization system should have decimeter-level to centimeter-level accuracy.However,current localization technologies based on RFID,Bluetooth,WiFi or ZigBee can not meet this requirement.In this case,this thesis propose that apply the UWB localization technology which has 10cm localization accuracy in theory to the indoor parking areas localization system,so as to help drivers find the target parking space quickly and easily.The main work and results of the thesis are as follows:(1)The indoor parking areas localization system is designed and implemented.DW1000 RF transceivers and STM32F105 are chosen to design anchors and tags.The software platform is built,which includes the embedded software in the distance measurement layer,the position calculation software in the position calculation layer and the server software in the store and display layer.TDM mechanism is used to achieve that one channel was shared by multiple tags.(2)An advanced distance algorithm based on SSA-TWR ranging mechanism is proposed to decrease the error of ranging caused by clock drift.The TOF error expressions of this advanced distance algorithm and three common distance algorithms are derived in detail.Depending on these TOF error expressions,ranging errors of these four ranging algorithms caused by clock drift are simulated and compared on the MATLAB platform.Finally,it's proved that the advanced distance algorithm proposed in this thesis can minimize the ranging error caused by clock drift.Therefore,this advanced distance algorithm is used to calculate the range between two nodes in this system.(3)The antenna delay calibration parameter is obtained through a large number of experiments,and the ranging error caused by antenna delay is corrected.The constrained linear least square localization algorithm is used to calculate the tag position.(4)Some experiments are designed and carried out,including the ranging experiments of some fixed distance between two nodes,the localization experiments of a single tag and multiple tags,and the tracking experiments of a mobile tag.The result of experiments shows that the accuracy of ranging is less than 5 cm,the accuracy of localization is not more than 20 cm,and this system has a good ability of tracking mobile tag nodes.