Monocular-Vision-Based Relative Pose Estimation of Noncooperative Spacecraft Using Multicircular Features

Accurate relative pose (position and orientation) estimation for noncooperative target spacecraft is the basic module for on-orbit services, such as capture and repair. This article technically proposes a nonlinear optimization method based on monocular vision to estimate the relative pose for the solid-of-revolution-shaped noncooperative spacecraft. Specifically, considering the multicircular features on the target, the parameters of the ellipses derived from the circles perspective projection are first obtained by the propounded ellipse detection algorithm. Moreover, the constraint that the center of each circle falls on the center axis (normal direction) of the spacecraft is utilized to optimally solve the center position and the normal of the multicircles. In particular, the roll angle around the center axis is recovered through the geometric constraints of the solar panels, and the six-degree-of-freedom spacecraft pose estimation is then accomplished. Consequently, it is analyzed that the proposed optimization algorithm is able to provide a closed-form solution to ensure the accuracy of the relative pose and only requires limited computational resources. Finally, experimental results on the synthetic images and the physical scenes are conducted to evaluate the efficiency of the proposed approach.