Hybrid Periodic Time-Varying Attitude Control Using Mixed Combination of Actuators

A continuous time-invariant controller design approach augmented by a discrete linear-matrix-inequality (LMI)-based control scheme is developed for spacecraft hybrid attitude regulation using the mixed combination of actuators, namely, magnetic torquers and impulsive thrusters. Magnetic torquers can generate control torques in a continuous manner, and impulsive thrusters can yield control torques at some discrete time instances. A hybrid attitude controller is then developed in two consecutive parts. In the continuous flow part, the time-varying nature of spacecraft magnetic attitude control is utilized to develop a pseudoinverse-based control scheme facilitated by a time-invariant average system. In the discrete jump part, the control scheme is formulated with linear matrix inequalities. Closed-loop stability is analyzed when the proposed hybrid attitude controller is implemented on spacecraft attitude regulation. Numerical simulations demonstrate the effectiveness and control performance enhancements of the proposed hybrid control scheme compared to the pure magnetic attitude control scheme.