Autonomous guidance and control for rendezvous and mating with gateway with collision avoidance maneuvering

Gateway will represent a vital asset for future lunar and deep space exploration. This research considers a chaser vehicle that aims at approaching and mating with Gateway, through the use of low-thrust propulsion for orbit control and reaction wheels for attitude maneuvering. Orbit dynamics of Gateway is simulated in a high-fidelity ephemeris-based dynamical framework, while the approaching path of the chaser is modeled through a modified Battin–Giorgi formulation, suitable to describe the translational motion relative to the strongly perturbed orbit traveled by Gateway. Rendezvous and mating is achieved through three subsequent phases, i.e. (1) close range rendezvous, (2) terminal approach, and (3) final drift and mating. In phases (1) and (2) two distinct feedback laws (i.e., nonlinear hybrid predictive control and feedback linearization) provide the thrust direction and magnitude, while in phase (3) the spacecraft naturally drifts (with no propulsion) while performing attitude maneuvering, aimed at final correct alignment. In powered arcs, the time-varying thrust components identify the commanded pointing direction of the spacecraft, and a nonlinear control algorithm, which enjoys global stability properties, is used. Strict collision avoidance constraints, with the definition of a suitable exclusion region and an effective emergency maneuver, are included in the real-time iterative update of the tracked trajectory. Two mating options are considered, i.e. (a) docking and (b) berthing. Numerical simulations in nonnominal flight conditions point out that the nonlinear control techniques developed in this study are effective for autonomous spacecraft rendezvous and mating with Gateway.