  This paper discusses spacecraft control using variable-speed CMGs. A new
operational concept for VSCMGs is proposed. This new concept makes it possible
to approximate the complex nonlinear system by a linear time-varying system
(LTV). As a result, an effective control system design method, Model Predictive
Control (MPC) using robust pole assignment, can be used to design the
spacecraft control system using VSCMGs. A nice feature of this design is that
the control system does not have any singular point. A design example is
provided. The simulation result shows the effectiveness of the proposed method.
