Tube-Based Model Predictive Control for the Approach Maneuver of a Spacecraft to a Free-Tumbling Target Satellite

We present a tracking controller for the rendezvous of a robotic chaser satellite to a free-tumbling target satellite in the presence of uncertainty in the predicted target motion, applicable in real-time. The maneuver to be controlled is modeled on the e.Deorbit scenario. The path followed by the chaser in the orbital frame is based on a prediction of the target motion and is provided by a motion planner. For the robust control of the maneuver, a linear tube-based robust model predictive controller is proposed, which will guarantee feasibility and stability for a predefined uncertainty in the target motion. The control problem is itself linear, permitting controller formulation using the linear framework. However, the relation between the uncertainties of the maneuver participants is nonlinear, which complicates the controller design. The controller is evaluated in simulation, the results of which depict its effectiveness for a realistic uncertainty boundary.