Performance Validation and Comparison of Range/INS Integrated System in Urban Navigation Environment Using Unity3D and PILS

Since the developments of a navigation system that relies mostly on real flight experiments in the GNSS-challenged, urban environments are expensive, the verification and modification process of the prototype system through implementing its simulator takes great advantages. In this study, the objective navigation system under consideration assumes the range/INS integration with an urban GIS map data and GNSS-denied condition. Most fundamentally, in developing the simulator with distributed components, the Unity3D's game engine is adapted as a useful tool for fast map processing and implementing similar flight environments to urban navigation. Moreover, it differentiates itself from other simulators in that it can reduce development costs by making various test runs more comfortable through a manual flight and real-time navigation performance verification. In implementing simulator components, an IMU, multiple rangefinders, barometer, and GPS receiver are modeled considering practical sensor characteristics. Using the measurement difference between the range sensor and the predicted range information calculated from the stored 3D map database in areas of interest, the navigation filter is implemented for combining range residual with INS. The completeness of navigation and simulator is achieved by incorporating the actual noise characteristics observed from real flight tests into the simulator and analyzing estimation performance via mutual comparison.