Precise Relative Positioning in GPS-Degraded Environments using a DGPS/UWB Navigation Filter

With the rising popularity of UAV/UGV cooperative teams for commercial and industrial use, accurate relative positioning of the UAV must be sustained through a variety of environments. Sensor suites based around RTK-DGPS are a common approach. But for many environments, multi-path or cycle-slip inducing maneuvers can further degrade or prevent fixing the integer ambiguities needed for precise navigation. Furthermore, UAVs are often considered expendable and thus come with low-cost sensors in many commercial applications. These low-cost sensors can not provide the needed accuracy for certain applications in addition to requiring a longer initialization period due to single frequency limitations. This paper presents the experimental validation of a decimeter-level navigation solution by utilizing a tightly-coupled fusion of low-cost differential GPS (DGPS) and Ultra-Wideband radios.