Low-speed friction compensation of reaction wheels using command shaping

The friction discontinuity at low-speed of reaction wheel causes an undesirable impulsive jerk disturbance in spacecraft control system. In order to compensate the disturbance of static friction discontinuity, this paper proposes a simple and effective friction compensation method applying a command shaping technique to the wheel command torque. A simulation of the three-axis spacecraft attitude control system with reaction wheel is performed and the usefulness of the proposed command shaping to deal with the nonlinearity of the reaction wheel is demonstrated. The friction compensation method suppresses an undesirable impulsive jerk disturbance from the static friction discontinuity in reaction wheel and minimizes control error in attitude control system of spacecraft.