Abstract: The model of AMB rotor control system in industry can not manifest the gyro effect in CMG, so that it isinconvenient to design the control law against the rotor vortex. A system moeel based on the rotor translation androtation is introduced , and the gyro effect is clearly reflected. The backward vortex under different methods of AMBcontrol including the decentralized control and cross2feedback control are analysed. The concept of Modal DecoupleControl is put forward , and the backward vortex of rotor can be diminished at original offset situation and better stability is achieved under this control law.

Key words: gyro dynamics, active magnetic bearing, decouple control