Study on an auto-landing guidance for UAV with engine flame-out

Abstract

Landing is the most dangerous phase of entire flight phases. If total loss of thrust occurs during flight, a powered aircraft converts to a glider, which can use kinetic and potential energy only. For this reason, a proper scheme is needed for safe landing in cases of total loss of thrust. Researches about unpowered landing have been widely performed. However, the platform of previous studies is mainly reusable launch vehicle (RLV) like a space-shuttle. Moreover, researches about the vertical plane have been mainly performed, and studies about the horizontal plane have not been conducted much. Therefore, this dissertation presents three-dimensional unpowered auto-landing guidance based on trajectory generation, expanding the concept of the energy-to-range ratio.

The terminal velocity estimation method for a horizontal plane to apply to three-dimensional space is proposed

this method is based on the previously suggested terminal velocity estimation method for a vertical plane. Then, trajectory generation for landing guidance combining vertical with horizontal waypoints is shown and the proposed auto-landing guidance with trajectory generation is evaluated by numerical simulation. For numerical simulation, a fully functional guidance and control law, including waypoints guidance and the classical feedback control law, are also designed. An investigation about a generated trajectory change according to the induced drag factor variations is also conducted. Furthermore, a scheme to improve the performance of an unpowered auto-landing under steady wind conditions is studied, and the proposed performance improvement method is evaluated by numerical simulation.