Non-cooperative spacecraft proximity control considering target behavior uncertainty

The significant characteristics of space non-cooperative targets include the uncertainties of dynamic parameters and behaviors. Herein, a hybrid proximity control strategy adapted to the behavior uncertainty of a non-cooperative target is presented. First, the relative motion dynamics between the chaser and target is established in the geocentric inertial coordinate system and transcribed based on the chaser spacecraft body coordinate system. Subsequently, to facilitate proximity control under uncertain conditions, an extended state observer is designed to estimate and compensate for the total uncertainty in the relative motion dynamics. Finally, an event-triggered sliding mode control law is designed to track the target with behavior uncertainty and realize synchronization. Numerical simulations demonstrate the effectiveness of the proposed proximity control strategy for both tumbling and maneuvering targets.