Time-optimal magnetic attitude control for small spacecraft

Spacecraft attitude control using only magnetic coils suffers from a slowly varying uncontrollable axis. This lack of controllability results in slow slew maneuvering and convergence to equilibrium positions. In this paper the time optimal control solution for magnetic attitude control is 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 some time-critical applications.