Research On Technology Of Integrated Positioning With BDS And UWB

The Beidou satellite's direct path is blocked in complex environments,such as cities,canyons,port containers,etc.The user cannot complete positioning due to insufficient observable satellites.At this time,an auxiliary positioning system must be introduced to enhance its positioning function.UWB auxiliary positioning system can provide BDS with its missing observations.The deployment of UWB base stations can enhance the geometric distribution of BDS and reduce GDOP.Because UWB has a wide bandwidth and narrow pulses,it can provide BDS with high-precision ranging information to achieve the purpose of improving positioning accuracy.Therefore,the study of BDS and UWB combined positioning technology has important theoretical value and practical application prospect.The main work completed in this thesis is as follows:1.Research on UWB positioning technology.Explain the basic principles of UWB,including its definition,mathematical expressions of signals,and its advantages in the field of positioning.Study and simulate the TOA positioning algorithm,and analyze the effects of ranging errors,the number of base stations,and the location of the base station on its positioning performance.2.Establish a pseudorange fusion positioning model of BDS and UWB.Establish a pseudorange comprehensive observation equation for BDS and UWB integrated positioning through the respective observation equations of BDS and UWB.Design the layout scheme of UWB base station based on the principle of minimum GDOP and perform simulation verification.The positioning error of the pseudorange fusion positioning model is analyzed.3.Study the classic positioning algorithm of BDS and UWB integrated positioning.Including Newton's iterative LS algorithm,?-? filtering algorithm,KF algorithm,EKF algorithm and UKF algorithm,they are evaluated from applicable scenarios,advantages and disadvantages,and positioning accuracy.4.Aiming at the problem of unreasonable weight distribution of different observations in the BDS and UWB comprehensive observation equations,an adaptive weighted WLS-KF positioning algorithm based on pseudorange residual detection is proposed based on the LS-KF positioning algorithm.In this way,the problem of uneven weight distribution between different observation satellites and UWB is effectively solved,and the positioning accuracy is improved.5.Aiming at the problem of Kalman gain locking after multiple observation epochs,a Kalman gain adaptive LS-KF positioning algorithm is proposed.This algorithm maps the pseudorange residuals to an adaptive factor through a mapping function.According to the adaptive factor,the Kalman gain is further adjusted based on the original Kalman gain.This algorithm can improve positioning accuracy and enhance anti-interference ability.