Comprehensive Evaluation of Robust and Tight Integration of UWB and Low-Cost IMU

With the rapid development of the Internet of Things (IoT), indoor positioning method with characters of high accuracy, continuity, and reliability has become an urgent requirement. Although the global satellite navigation system (GNSS) can provide that information in open-sky conditions, it still cannot work in GNSS-denied environments. To counteract the drawbacks of GNSS and conventional low-accuracy indoor technologies, this article presents a credible indoor positioning system with integrating ultrawide-band (UWB) measurements and low-cost inertial navigation system (INS) tightly. Based on such a system, the impacts of non-line-of-sight (NLOS) errors, the distribution of UWB base stations, the number of UWB base stations, and the rate of UWB data on UWB/INS tight integration are evaluated comprehensively by analyzing three sets of experimental data and several groups of simulated data. Results demonstrate that: 1) UWB/INS integration upgrades UWB positioning accuracy significantly, with decimeter-level positioning accuracy in the horizontal component and meter-level accuracy in the vertical direction while using the UWB/INS tight integration model; 2) the influences of the geometry structure of the UWB base station on the performance of UWB and the UWB/INS loose integration are obvious, and such an influence on the performance of the UWB/INS tight integration is slight; 3) the positioning accuracy of UWB/INS tight integration increases gradually along with the rate of UWB data; and 4) the presented method shows visible repression of the influence of NLOS errors on UWB/INS tight integration.