CLOSED-LOOP MOMENTUM-TRANSFER MANEUVERS USING MULTIWHEELS

This paper proposes a control law that stabilizes a momentum transfer maneuver using multiwheels, which provides an analytical proof via Lya punov's direct method. Since an open loop transfer sometimes causes di vergent and targe nutation motion, especially when a minor to major ax is transfer is attempted, the closed-loop scheme is discussed here, Th is paper also points out equilibrium ''singular states'' which may occ ur not only in open loop but also in a closed-loop momentum transfer, from which no evasive path can be found. This paper provides sufficien t conditions by which both divergent behavior and singular states can be circumvented by appropriately selecting the control law proposed he re or by use of inertia properties of the spacecraft. This may be the most distinct feature of a closed-loop transfer utilizing multiwheels vs conventional open-loop schemes. This paper shows that neither the o pen-loop method nor closed-loop control with a single wheel system avo ids these undesirable phenomena. The proposed control scheme with four wheels is numerically demonstrated to improve significantly the trans fer behavior and exclude any singular state occurrence.