Experimental Assessment of a Visual-Laser Relative Navigation Module for CubeSats

This paper presents the Hardware-In-The-Loop testing of a multi-sensor relative navigation module enabling close-proximity operations toward passively cooperative space targets in the frame of On-Orbit Servicing missions. The module, which is designed according to the CubeSat standard to occupy two CubeSat units, consists of a monocular camera and a wide-field-of-view laser range finder, and exploits a sensor fusion logic to provide relative position and attitude (pose) estimates. A laboratory setup is conceived and realized to characterize the pose estimation performance of the module by providing a highly accurate benchmark. Experimental tests show that the module is able to measure its relative position and attitude with respect to a target at operative distances below 2 meters with millimeter and tenths-of-degree level accuracy, respectively. Further tests on a larger-scale trajectory in an uncontrolled environment (in terms of illumination conditions and reference pose solution) demonstrate the capability to perform pose estimation up to operative distances of about 9 meters from the target, keeping reprojection errors at sub-centimeter level, and collecting reliable range finder measurements up to 30 m.