Simple and efficient algorithm is developed to identify the unbalance distribution of rigid rotor supported by active
magnetic bearings (AMB). The complex unbalances are obtained by solving the simultaneous equations formulated
with influence coefficient matrices associated with bearing stiffness and damping matrices. The algorithm takes
advantage of AMB’s ability to adjust the bearing stiffness and damping through feedback control. The algorithm is
applied to a rigid rotor-AMB system and its validity is demonstrated numerically.