Monocular Visual Pose Estimation for Flexible Drogue by Decoupling the Deformation

During aerial refueling, the flexible structure of the drogue stabilizing umbrella will inevitably deform. Conventional feature correspondence-based methods fail to work when the drogue suffers deformation. By decoupling the deformation, a monocular visual pose estimation method of flexible drogue is proposed to overcome the problem. First, the space invariant features of the drogue are nominated by analyzing the structure and deformation of the drogue. Subsequently, the deformation in the constraints on feature correspondence is decoupled by establishing the model coordinate system. Next, the initial solution is solved by means of the structural constraints between the model coordinate system and the world coordinate system of the drogue. After that, the optimal pose is obtained by the optimization of the rotation-invariant function. Ultimately, the effectiveness and robustness of the proposed method are verified. The results sufficiently show that our method provides excellent resistance to flexible drogue deformation along with an outstanding real-time performance, and our method outperforms the others in all evaluation metrics under identical conditions.