Variance Optimization Of Uwb Observation Based On Map Matching For Ppp/Ins/Uwb Tightly Coupled Positioning

Ultra-wideband (UWB) is essential in precise point positioning (PPP)/inertial navigation systems (INS)/UWB integrated navigation with the advantage of highly accurate observations. However, its accuracy could be affected by its sparse distribution, limited operating distance and low space height. In a dynamic environment, it is not easy to determine its variance precisely for an integrated system. Sometimes, the system performs poorly due to improper variance. In this paper, a map-matching variance optimization of UWB observation was firstly developed for tightly coupled positioning. Instead of the characteristic analysis of the UWB signal directly, the optimization can be realized based on the accuracy of PPP/INS solutions. The proposed map-matching algorithm can be adopted to access the accuracy of PPP/INS and determine the optimization factor so that the variance of UWB can be dynamically obtained. Then, the variance was adopted in the stochastic model of the PPP/INS/UWB system. The actual experiments were conducted to validate the proposed method under two different scenarios, and the effectiveness of this method was analysed. The results indicated that the proposed method could obtain suitable variance and improve the performance in both these two scenarios.