Research And Implementation Of TDOA Location Algorithm Based On UWB Technology

With the development of information technology,people nowadays is increasingly dependent on the spatial location information.There are many positioning techniques for spatial location,such as ultrasonic positioning technology,RFID(radio frequency identification)positioning technology,Bluetooth positioning technology,WiFi positioning technology,ZigBee positioning technology and UWB(Ultra-wideband)positioning technology.Accordingly,there're a large number of positioning algorithms:RSSI positioning algorithm,AOA positioning algorithm,TOA positioning algorithm and TDOA positioning algorithm.The introduction and advantages and disadvantages of these positioning techniques are briefly described in the second chapter of this paper,and the above-mentioned positioning algorithm is also introduced and compared in the third chapter of this paper,so that there are not introduced in here.The rapid development of positioning technology taken for granted,it also shows that the demand for location.In this paper,the TDOA localization algorithm commonly used in UWB positioning system is studied and tested.TDOA positioning algorithm actually uses the time difference of the receiving time of the signals to locate.Usually we get the base station to receive the signal,by which to determine the distance between the signal source and the base station.A circle is drawn using the distance of the signal source to various base station as the radius,and the intersection of the circles is the location of the signal source.Because the absolute time is generally not easy to measure,the arrival time difference can be used to build the hyperbola,using the base station as the focuses.The arrival time difference multiple the speed of light is the distance between the base station and the signal source,which is the points consisting the hyperbola.The intersection of multiple hyperbolas is the position of the signal source.The description above is the hyperbolic mathematical model.This paper first makes a general understanding of the development of UWB positioning technology domestic and abroad,studies its theory,and the commonly used positioning performance index has also been briefly introduced.Then,the theory and mathematical model of TDOA localization algorithm in this chapter are further researched,and the clock synchronization between base stations needed by TDOA localization algorithm is studied.A method based on Kalman filter algorithm is proposed and the corresponding mathematical model is established.Through the simulation results,it's proved that the synchronization among the base stations is very good with the Kalman filter algorithm-tracking.Finally,the nonlinear equations of TDOA algorithm are solved.Two commonly used classical position estimation algorithms are introduced:Fang algorithm and Chan algorithm.And the simulation experiments are carried out respectively.The results show that the Chan algorithm is better than the Fang algorithm.The Fang algorithm can not use the redundant base station information to estimate,while Chan's can't,so Chan algorithm can increase the base station to improve the positioning accuracy.Simulation results also show that the Chan algorithm by increasing the number of base stations to improve the positioning precision is limited,when the number of base stations to achieve a certain number,the improvement of the positioning accuracy is not obvious.Therefore,the Chan algorithm demands for the number of base stations depending on the situation in the practical engineering application.