Application of model aided inertial navigation for precise altimetry of Unmanned Aerial Vehicles in ground proximity

In this research, Model Aided Inertial Navigation (MAIN) is used during the automatic landing of an Unmanned Aerial Vehicle (UAV). A new MAIN algorithm is proposed which is fast and accurate enough to be used in this phase. In this algorithm, the six Degree of Freedom (6DoF) flight simulation of the UAV is integrated with the Inertial Navigation System (INS) such that the 6DoF model acts as an aiding system for the INS. In the last parts of the landing phase, when the UAV flies in proximity of the ground surface, the proposed integrated navigation system can estimate the altitude of UAV utilizing the “ground effect” phenomenon. Therefore, the method does not have the drawbacks of active altimeters such as cost, weight and dependency to weather conditions, surface type and attitudes. Simulation results show that the altitude estimation by the new MAIN algorithm converges in a fraction of second, and the accuracy is acceptable for a precise automatic landing.