Automatic differentiation based nonlinear model predictive control of satellites using magneto-torquers

Satellite control using magneto-torquers represents a control challenge combined with strong nonlinearity, variable dynamics and partial controllability. An automatic differentiation based nonlinear model predictive control (NMPC) algorithm is developed in this work to tackle these issues. Based on the previously developed formulation of NMPC, a novel variable sampling time scheme is proposed to combine with the NMPC algorithm so that both control performance, particularly the response speed when the satellite is far away from the desired position, and the closed-loop stability when the satellite is at its equilibrium position can be comfortably satisfied. The proposed approach is demonstrated through nonlinear simulation of a specific satellite case with satisfactory results obtained.