High Precision Positioning Technology And Target Tracking Based On UWB In Indoor Environment

With the vigorous development of various industries in the society and the remarkable progress of wireless communication technology,wireless sensor networks have been applied to more and more aspects,among which the indoor localization have received much more attentions.Therefore,it is urgent to find a low-cost,faster-speed,and higher-precision localization technology in the available spectrum resources become increasingly tense.Ultra-wideband(UWB)technology becomes popular due to its dramatic properties,such as ultrawide bandwidth,high transmission rate,high time resolution,strong resistance to multi-path fading,low transmit power,and high confidentiality,and it has gradually become the first choice for high-precision indoor localization,being considered as one of the top ten technologies for future communications.In this thesis,based on UWB communication,the traditional algorithm used in the TDOA localization method of UWB is improved.The main research contents are summarized as follow:1.This chapter introduces the principle of UWB signals.The most widely used implementation of UWB signals is investigated on the transmitter structure of impulse radio and the generation of impulse radio signals.The widely used Gaussian pulse waveforms and energy spectral density are simulated and analyzed.The simulation implements two modulation methods for UWB signals,namely PPM-TH-UWB and PAM-DS-UWB.The channel model based on the IEEE 802.15.4a standard is mainly introduced.The coherent and non-coherent methods used for detecting and processing signals are analyzed.The receiver structure of the two methods is studied.2.This chapter mainly analyzes several ranging based localization methods,such as TOA localization method,TDOA localization method,AOA localization method and RSSI localization method.The advantages and disadvantages of each localization method are compared,and then,the TDOA-based localization method are determined as the main research object,and we also analyze the influencing factors of the localization accuracy.3.Several traditional localization algorithms based on TDOA localization methods such as LS algorithm,WLS algorithm,Fang algorithm,Taylor algorithm,and Chan algorithm are studied.Three algorithms of Fang,Taylor and Chan are simulated and the accuracies of localization are compared.By combining the advantages of the Chan algorithm and the Taylor algorithm,the localization accuracies are improved.The location tracking of moving target is studied.Kalman filtering algorithm is introduced.Kalman filtering algorithm is used to improve the three localization algorithms of Fang,Taylor and Chan.The combination of Chan algorithm and Kalman filter is selected through simulation and comparison.The algorithm improves the accuracy of localization and tracking of moving targets.Finally,the mobile robot platform and localization kit are used to carry out the localization experiment.The experiment verified the feasibility of the improved algorithm,and its localization accuracy performed well.