A vision-based relative navigation sensor for on-orbit servicing of CubeSats

Abstract

It has been anticipated that CubeSats would have wide applications in on-orbit servicing (OOS) fields due to their advantages of short research and development cycle and low manufacturing cost, in which the close-range relative navigation is a critical technique that usually requires high accuracy of the relative pose estimation. This paper proposes a vision-based relative navigation sensor for OOS of CubeSats. A set of active fiducial markers with multi-layer structure was designed to ensure an accurate unambiguous matching and measurement. An improved effective perspective-n-point (IEPnP) algorithm is developed to obtain an accurate relative state estimation. An experiment system which simulates the real illumination and motion conditions in space was set up to assess the performances of the proposed sensor. The results show that the sensor can overcome the interference of the ambient light, and can reach an accuracy of range estimation smaller than 2 mm and an accuracy of relative attitude estimation smaller than 0.4 deg at distance of 1 m. Through contrast tests, the accuracy of the proposed IEPnP algorithm is better than the classical perspective-3-point (P3P) algorithm and EPnP algorithm.