Research on Landing Attitude Control of Terrain Adaptive UAVs

When landing on unstructured terrains in the field, UAVs often cannot go-around as they tilt on the ground, and even face the risk of roll-over with the attitude angles increasing. In this paper, a terrain adaptive UAV with adjustable landing legs is designed aiming at the stable landing and going-around requirements of multirotor UAVs under unstructured terrain conditions. a drop dynamic model of UAV is described in detail and drop simulation on flat ground is carried out in MATLAB/Simulink to verify the landing performance of UAV. The VMC method is used to establish the UAV’s landing attitude control loop, which adjusts the landing legs actively through the feedback of attitude angle to suppress the variation of landing attitude caused by the terrains. The results of UAV’s drop simulation under the terrain with height difference show that the attitude angle converges quickly to a range suitable for going-around during the landing process.