About the Influence of the Magnetic Suspension on Noncontact Gyroscope Dynamics

Stable levitation of rotors in noncontact gyroscopes with magnetic suspension is provided by a system of automatic regulation (SAR), which converts the signal of the rotor drift from an equilibrium position into the control signal changing the currents in electromagnets to the desired direction. The absence of special transducers of rotor position is a characteristic feature in the majority of devices [1], because the rotor drift with respect to the suspension poles changes their inductance. This fact provides the appearance of the input signal of the SAR, which, in an ideal case should respond only to the translational displacements of the rotor's center of masses and should be insensitive to its angular movements. Because of the residual unbalance of the rotor [2] and its shape deviation from the spherical one, the SAR responds not only to the translational motions, but to the angular motions as well. The phase shifts of harmonic components of the input and output signals lead to the appearance of non conservative forces and mOlllents, influencing the value of the angular momentum of the gyroscope and its "precession" and "nutation" stability. It is shown in this paper that even in the case of a perfectly balanced rotor stably hanging in the suspension field, the self- modulation stipulated by the rotor surface asphericity can lead to instability of its angular motions.