Control of a Thrust-Vectoring CubeSat Using a Single Variable-Speed Control Moment Gyroscope

A minimal actuator design is proposed for orbit-attitude control of a spacecraft. The actuator design includes a single thruster, fixed in the body frame, and a variable-speed control moment gyroscope (VSCMG) used for thrust vectoring. It is known that the full attitude cannot be controlled using a single VSCMG, but that a single axis is controllable. This paper develops a nonlinear control that is able to vector the thruster at discrete intervals or continuously. The closed-loop stability of the system is proved using Lyapunov stability theory for each control law. These control laws could enable high maneuverability of CubeSats, using either a single chemical (impulsive) or electric thruster (continuous). The controls are demonstrated, in simulation, with an application to a 12U CubeSat rendezvous using a single throttable electric thruster.