Linear Time-Varying Passivity-Based Attitude Control Employing Magnetic and Mechanical Actuation

Spacecraft attitude control using both magnetic and mechanical actuation is considered. A passivity-based control scheme is adopted in order to guarantee robust closed-loop stability. Motivated by the periodic nature of the Earths magnetic field a linear time-varying input strictly passive system is used for control. Conditions which ensure a linear timevarying system is input strictly passive are given, and are used in conjunction with the linear quadratic regulator formulation to design and synthesize the rate control. Simulation results are included, which highlight the robust nature of the closed-loop subject to both orbit, and spacecraft model uncertainty.