Suboptimal attitude control of a spin-stabilized axisymmetric spacecraft

Necessary conditions are developed for the fuel-optimal attitude control of a spin-stabilized axisymmetric spacecraft for which control torques are generated by means of a gimballed reaction-jet system. Solutions are developed, based on Lawden's [1] impulsive approximation, for the free-time fuel-optimality criterion. A control logic is proposed for realizing the derived impulsive solutions by means of an orthogonal reaction-jet system. The proposed system requires angular measurements but does not require angular-rate measurements. Pulsewidth modulation is used to generate approximate impulses of varying magnitudes.