Abstract
This paper deals with three-dimensional attitude control of spacecraft equipped with four thrusters whose directions are fixed to the spacecraft. The adopted four-thruster-configuration is very useful, because it can generate independent torques around the three principal axes of the spacecraft in spite of only four thrusters. This paper designs a controller based on a sliding mode control theory, because the theory is known to have robustness to modeling errors and external disturbances. Then, the control torques required for the sliding mode control are distributed to the four thrusters based on the nominal model of the spacecraft. Finally, the effects of the modeling errors are investigated in numerical simulations.
