For small satellites, the attitude architecture of choice is often spin stabilization. Spin stabilization of a satellite about its major axis typically leads to a need for on-board active nutation damping. Spin stabilization of a satellite about its minor axis is typically not considered as a design option, due to the inherent instability of the minor axis spin in the presence of energy dissipation. This work considers the design of nutation damping and spin stabilization systems for small spinning spacecraft.; Nutation damping systems are designed around two distinct actuators. The first actuator considered is a magnetic torque rod, aligned with the desired spin axis, and operated in a bang-bang control mode. The torque rod has the advantage of being simple and inexpensive to build, requiring no expendables, and having extremely high reliability due to its lack of any moving parts. However, magnetic control suffers from the disadvantages of small control torques and limit control authority. The second actuator considered is a small reaction wheel mounted with its axis orthogonal to the desired spin axis. The reaction wheel system also requires no expendables, and is commercially available to satellite designers. Although the reaction wheel is a mechanical system with inherent reliability issues, the technology is mature and has ample spaceflight heritage.; The control law design approach adopted here employs Lyapunov stability theory. Because this technique has not seen extensive use in attitude control applications, we first apply it to attitude stability problems for which the solutions are well understood. Thus, we provide new insight into the stability analysis of the pure spin motions of bodies experiencing energy dissipation. Satisfied that the technique is applicable to the study of spinning bodies, we then employ it to design the active nutation damping control laws of interest. The resulting control laws compare favorably to existing laws found in the literature for each of the actuators considered.
展开▼
