Navigation-aware waypoint-based guidance and control for spacecraft close-proximity operations

The paper presents a Guidance Navigation and Control (GNC) architecture designed for proximity operations around uncooperative space target, i.e. spacecraft of known geometry but lacking inter-satellite communication link or fiducial markers to ease the relative state estimation task. The proposed architecture integrates a classical Kalman filter for relative navigation with a PID controller to ensure the alignment of the boresight axis of the relative navigation sensor, a LIDAR in this case, with the target-chaser line of sight. The translational control task is instead addressed using a waypoint-based strategy. A key innovation of this work lies in the introduction of an adaptive deadband for the translational control function. The deadband is adjusted dynamically based on the predicted control error, derived from the current covariance estimate provided by the relative navigation filter. The performance of the proposed architecture has been validated in a high-fidelity numerical simulator in both far range and close range scenarios. Results highlight the effectiveness of the architecture in reducing the number of required firing cycles, and, consequently, the propellant consumption, thereby enhancing the mission lifespan.