GUIDANCE AND CONTROL OF AUTOMATIC SHORT LANDING WITH STEEP GLIDE SLOPE FOR UAV

摘要

This paper presents the guidance and control law designed for the automatic landing sequence of a tactical-level UAV that is required to follow a steep landing slope. The automatic landing system consists of a precision location tracker and a flight control computer. The guidance and control law is developed to filter and switch between navigation signal sources and generate control surface commands to keep the UAV within the boundaries of its landing trajectory. A two-stage flare maneuver is suggested to overcome difficulties associated with having to maintain a steep approach slope for landing in mountainous terrain. The performance of the automatic landing system was verified through the Hardware-In-the Loop testing and flight tests, which confirmed that the two-stage maneuver assured the UAV to attain high levels of touchdown accuracy and a sufficiently low vertical speed to satisfy its landing requirements.