COAXIALITY CALCULATION METHOD FOR DROPPING OPERATION OF LUNAR SURFACE SAMPLING MISSION BASED ON MONOCULAR VISION USING ELLIPSE AND LINE FEATURES

Abstract. In the lunar surface sampling mission, the drop operation that transferring the packaging container into the sample return container is a vital step. In this paper, for supporting the drop operation, we proposed a method to measure the coaxiality between the two containers based on the monocular vision pose measurement using ellipse and line features. The method first extracts ellipse and line features in the 2D image to calculate the initial parameters. Then, the initial parameters and the point set are used to fit the curve by the cylinder perspective contours fitting method, where the constraints between ellipse and line features are used to improve the robustness to varying noises. Next, given the fitting ellipse and camera parameters, the pose of the packaging container is solved by using circle-based method. Finally, the coaxiality of the two containers is calculated based on the relative pose between them. Simulation experiments were carried out and the results show the effectiveness and reliability of the proposed method.