Equilibrium points analysis for attitude control of spacecraft with two reaction wheels

The attitude of a spacecraft is usually controlled by more than 3 reaction wheels. Therefore, as a preparation for accidents of the wheels, it is important to consider the attitude control by 2 wheels. The purpose of this analysis is to find the feasible attitude by two reaction wheels under an initial angular momentum. When the initial angular momentum is not zero, a spacecraft has a drift term and the attitude cannot be controlled freely. Therefore, based on the equilibrium points analysis, this paper proposes the best antenna arrangement in terms of the attitude control by two reaction wheels. Moreover, a design algorithm of a controller that stabilizes a feasible attitude is provided by modifying our previous method.