STABILITY OF SINGLE AXIS GYROS IN A CIRCULAR ORBIT
The stability of single axis gyros mounted on a vehicle in circular motion about a central force field is examined for several orientations of the spin vector and output axis. When the orientation of the output axis is in the radial or tangential direction of the orbit, as in the case of pitch or roll sensors, the stability is dependent on the ratio of the spin angular velocity to the vehicle angular velocity around the orbit and the ratio of the moments of inertia of the gyro wheel. When the orientation of the output axis is fixed in inertial space, as in an inertial platform, the equations of motion are of the Mathieu type. The stability in this case is independent of the spin angular velocity of the gyro wheel and is a function of the moment of inertia ratio of the wheel, the angular velocity of the vehicle around the orbit, and the desired orentation of the spin velocity vector.