Calibration procedures of a vision-based system for relative motion estimation between satellites flying in proximity

Relative Measurements systems represent a key technology for next generation space missions that require proximity operations between satellites. Before on-orbit validation, the sensors and algorithms need to be validated in laboratory employing a good fiducial reference of the relative motion and specific calibration procedures concerning the estimation of roto-translation matrices between different reference frames. This paper presents a set of calibration procedures that allow to assess the accuracy in estimating the relative pose between a Target spacecraft, equipped with a set of square markers, and an Inspector satellite moving in proximity and hosting a monocular camera. An external Motion Capture system is used to track the motion of a set of spherical markers attached to both the Target and the Inspector, providing a reliable fiducial reference for the relative pose between the two spacecraft. The proposed calibration procedures were tested using the SPARTANS hardware facility of the University of Padova.