Robust Output-Feedback Control for Spacecraft Proximity Operations With Forbidden Zone

This article seeks to address the robust output-feedback motion tracking control problem for spacecraft close-range proximity maneuvers under the influence of forbidden zone, external disturbances, and input saturation. First, two superquadric cuboids are constructed in the body-fixed frame of the target to represent the forbidden zone in final proximity. Then, an adaptive output-feedback control scheme is proposed under the framework of extended state observer technique and sliding mode control methodology. The presented scheme can achieve concurrent position and attitude tracking without prior information of the velocity-level states, and avoid any unwanted collisions between the two spacecraft. Finally, simulation scenarios are investigated to show the effectiveness of the proposed control scheme.