Robust adaptive relative position and attitude control for spacecraft autonomous proximity

• A six degrees-of-freedom model for spacecraft proximity operations is presented.
• The external disturbances, parametric uncertainties and thrust misalignment are considered.
• The computational burden is decreased with element-wise and norm-wise adaptive algorithms.
• Uniformly ultimately boundedness of closed-loop signals is proved and the bounds can be regulated sufficiently small.

This paper provides new results of the dynamical modeling and controller designing for autonomous close proximity phase during rendezvous and docking in the presence of kinematic couplings and model uncertainties. A globally defined relative motion mechanical model for close proximity operations is introduced firstly. Then, in spite of the kinematic couplings and thrust misalignment between relative rotation and relative translation, robust adaptive relative position and relative attitude controllers are designed successively. Finally, stability of the overall system is proved that the relative position and relative attitude are uniformly ultimately bounded, and the size of the ultimate bound can be regulated small enough by control system parameters. Performance of the controlled overall system is demonstrated via a representative numerical example.