Vision-Based Relative Navigation and Control for Autonomous Spacecraft Inspection of an Unknown Object

This paper describes a vision-based relative navigation and control strategy for inspecting an unknown and non-cooperative object in space using a visual-inertial system. The proposed inspection spacecraft system relies solely on a calibrated stereo camera and a 3-axis gyroscope to maintain a safe inspection distance while following a circle trajectory around the object. The navigation system is based on image processing algorithms which extract the relative position and velocity between the inspector and the object, and a simple control approach is used to ensure the desired range and bearing are maintained throughout the inspection maneuver. Hardware implementation details of the VERTIGO Goggles system are provided, and design considerations related to the addition of the stereo camera system and associated processor unit to the SPHERES satellites are discussed. Computer simulation results, and experiments conducted aboard the International Space Station during Expedition 34 are reported to demonstrate the performance and applicability of the proposed hardware and related navigation and control systems to inspect an unknown spacecraft.