Constrained spacecraft attitude control on SO(3) using fast nonlinear model predictive control

In this paper, a fast solver for the optimization problem arising in the nonlinear model predictive control of spacecraft attitude is developed and simulation results of its application to constrained spacecraft attitude control are presented. The solver exploits the numerical solution of the necessary conditions for optimality in a discrete-time optimal control problem defined over a prediction horizon, where the discrete-time dynamics are based on the Lie group variational integrator model. The inequality constraints (thrust constraint, inclusion/exclusion zone constraints, etc.) are handled using a penalty function approach. Our developments exploit the geometric mechanics and control formalism.