Singularity-Free Model Predictive Spacecraft Attitude Regulation Using a Variable-Speed Control Moment Gyroscope Model

This paper discusses spacecraft attitude control using variable-speed control moment gyroscopes. A new operational concept for variable-speed control moment gyroscopes is proposed, i.e., the flywheels and the gimbals of the variable-speed control moment gyroscopes do not always spin at high speed, they spin at high speed only when they need to. The dynamics of the variable-speed control moment gyroscopes are incorporated into the model for the control system design. The complex nonlinear system can be represented as an equivalent linear time-varying system. As a result, an effective control system design method, model predictive control using robust pole assignment, can be used to design the spacecraft attitude control system using variable-speed control moment gyroscopes. A combination of the new operational concept and a model that includes the variable-speed control moment gyroscopes' dynamics leads to several nice features: 1) the control system does not have any singular point; 2) the design reduces energy consumption because the fly wheels and gimbals are most likely operated at low speed when the spacecraft is stabilized; and 3) the theoretical analysis shows that the designed system is uniformly exponentially stable. A design example is provided. The simulation result shows the effectiveness of the proposed method.