  We design a reduced attitude controller for reorienting the spin axis of a
gyroscope in a geometric control framework. The proposed controller preserves
the inherent gyroscopic stability associated with a spinning axis-symmetric
rigid body. The equations of motion are derived in two frames: a non-spinning
frame to show the gyroscopic stability, and a body-fixed spinning frame for
deriving the controller. The proposed controller is designed such that it
retains the gyroscopic stability structure in the closed loop and renders the
desired equilibrium almost-globally asymptotically stable. Due to the
time-critical nature of the control input, in particular its sensitivity with
respect to delays/neglected dynamics, the controller is extended to incorporate
the effect of actuator dynamics for practical implementation. Thereafter, a
comparison in performance is shown between the proposed controller and a
conventional reduced attitude geometric controller with numerical simulation.
The controller is validated experimentally on a spinning tricopter.
