Optimal non‐linear feedback regulation of spacecraft angular momentum

Optimal non‐linear feedback laws are presented for the regulation of spacecraft angular momentum by using flywheels and by using fixed on‐off reaction jets. The control law for the flywheels takes the form of a linear combination of functions of the state, each positively homogeneous of degree 2 p ‐1 ( p 1/2); whereas the control law for the reaction jets is of bang‐bang form. The range (of the initial disturbance) over which the flywheels are capable of regulating the system and the problem of momentum dumping are also discussed with regard to flywheel saturation constraints. Finally, a control scheme combining the merits of reaction jets and flywheels is proposed.