Accurate Positioning for Refueling Plug with Coarse-to-fine Registration and Pose Correction*

Automatic refueling robot can free people from heavy work. However, work on the pose estimation of the refueling plug is relatively sparse. To this end, a novel precise positioning method for 6-DoF (Six-Degrees of Freedom) pose of the refueling plug is introduced based on coarse-to-fine template matching and pose correction. The coarse registration matrix is constructed by extracting 3D keypoints at the edge of the point cloud and combining with the geometric characteristics of the refueling plug. On the basis of coarse registration, fine registration is performed by aligning the main direction of the refueling plug handle. Through template matching, the grab coordinate system is constructed on the handle of the refueling plug, and the pose is corrected by modifying the grab coordinate system. The developed algorithm avoids building a large template library and reduces computing requirements. In addition, the accuracy and robustness of the 6-DoF pose estimation are proved on the automatic refueling robot.