Time-Optimal Magnetic Attitude Control for Earth-Pointing Spacecraft: Open-Loop and Continuous Optimization Approaches

Time-Optimal Magnetic Attitude Control for Earth-Pointing Spacecraft: Open-Loop and Continuous Optimization Approaches

Spacecraft attitude control using only magnetic coils suffers from a slowly varying uncontrollable axis. This lack of controllability results in marginal stability, slow slew maneuvering and convergence to equilibrium positions. In this paper the open-loop time-optimal control and continuous optimization solutions for magnetic attitude control of a nadir-pointing satellite are presented. Nonlinear time-varying models with constrained inputs are considered instead of the linearized model generally used. The time to reach equilibrium is less than that achieved by other conventional design methods, enabling magnetic attitude control to be applied to time-critical applications.