Global Descriptors for Visual Pose Estimation of a Non-Cooperative Target in Space Rendezvous

Abstract

This paper proposes methods based on global descriptors to estimate the pose of a known object using a monocular camera, in the context of space rendezvous between an autonomous spacecraft and a non-cooperative target. These methods estimate the pose by detection, i.e., they require no prior information about the pose of the observed object, making them suitable for initial pose acquisition and the monitoring of faults in other on-board estimators. An approach is presented to fully retrieve the object’s pose using a pre-computed set of invariants and geometric moments. Three classes of global invariant features are analyzed, based on complex moments, Zernike moments and Fourier descriptors. The robustness of the different invariants is tested under various conditions and their performance is discussed and compared. The method offers a fast and robust solution for pose estimation by detection, with a low computational complexity that is compatible with space-qualified processors.