Intelligent landing of Unmanned Aerial Vehicle using hierarchical fuzzy control

To improve the security of landing, the new purpose of confining all the touchdown states to their safe ranges is proposed instead of just trajectory tracking. The Integrated Landing Reference System (ILRS) provides sufficient and reasonable guidance information optimized considering the deflection margin, security margin and touchdown requirements. Inspired by the pilot´s experience, three-layer hierarchical fuzzy controller is designed to make the compromise between trajectory tracking and touchdown security. In the first layer, the sink rate and the pitch angle are coordinated based on the priorities allocated according to the security margins at different altitudes. The hybrid fuzzy logic plus Proportional-Integral (PI) controller is employed in the second layer and the third layer to provide expected response performances. The critical touchdown states are coordinated and protected through the simulation verification under the conditions of different uncertainties. The Monte Carlo simulation incorporated with various uncertainties shows that the intelligent landing improves the security and robustness significantly compared with traditional trajectory tracking.