Hardware-in-the-loop tests of a multi-sensor pose estimation module for small satellite inspection

The increasing number of space missions foreseen in the near future is motivating efforts to demonstrate In-Orbit Servicing (IOS) capabilities to improve the sustainability of the Earth orbit environment. In particular, the proliferation of small satellites is pushing toward the design and development of compact and low-cost technological solutions to enable autonomous close-proximity operations in orbit. In this context, this paper focuses on the relative navigation task presenting the latest updates on the Relative Positioning (RELPOS) Module, which integrates into two CubeSat units a monocular camera and a laser range finder operating in the near infrared band. Specifically, the paper provides a brief presentation of the functional and software architecture of the module, as well as of the experimental setup designed and realized for performance assessment. A campaign of hardware-in-the-loop tests is conducted highlighting that the RELPOS can perform both pose acquisition and tracking of a cooperative target equipped with retroreflective markers with mm-level and sub-degree level accuracy on relative position and attitude estimates, respectively.