Active stabilization of rotors with circulating forces due to spinning dissipation

Abstract

Destabilizing effects due to rotating dampers in gyrating or spinning systems govern their dynamic behavior very prominently. Tippe-tops and gyro-pendulums exhibit their seemingly counter intuitive behavior due to such dissipations. Rotors at speeds higher than certain threshold values become unstable due to rotating damping forces generated by dissipation in rotor material, couplings or due to friction in splines and tool tips. There are several techniques by which one may stabilize such rotors. Although the current methods in practice are quite effective for large or medium size rotors but these may not be suitable for small, mini or micro rotor systems. This paper proposes a class of alternative techniques to stabilize rotors any size through implementation of strategies developed here, however the selection of actuating mechanism would depend on the size of the rotor. In this paper the size of the rotor that may be actuated by piezo-electrical type actuators are considered. Thus may be called small size rotors. The rotor when it is not spinning is like two simple pendulums in two orthogonal planes (however when this rotor spins the cross coupling of motion between two planes takes place).