Optimal Control for Proximity Operations and Docking

This paper proposes optimal control techniques for determining translational and rotational maneuvers that facilitate proximity operations and docking. Two candidate controllers that provide translational motion are compared: A state-dependent Riccati equation controller is formulated from the nonlinear relative motion dynamics, and a linear quadratic tracking controller is formulated from the linearized relative motion. A linear quadratic Gaussian controller using star trackers to provide quaternion measurements is designed for precision attitude maneuvering. The attitude maneuvers are evaluated for different final axis alignment geometries depending on the approach distance. A six degree-of-freedom simulation demonstrates that the controllers perform proximity operations and docking successfully.