MODAL TESTING AND SUBOPTIMAL VIBRATION CONTROL OF FLEXIBLE ROTOR BEARING SYSTEM BY USING A MAGNETIC BEARING

A suboptimal output feedback controller is designed based on a reduced order model and applied to a flexible rotor bearing system in order to control the unstable or lightly damped vibrations occurring during operation. The reduced order model is a truncated modal equation of the distributed parameter system obtained through the singular perturbation. The instability problem arising from the spillover effects caused by the uncontrolled high frequency modes is prevented through the constrained optimization by incorporating the spillover term into the performance index. The application of the matrix minimum principle yields a set of matrix equation similar to the unconstrained output feedback controller. The efficiency of the proposed method is demonstrated experimentally with aflexible rotor by using a magnetic bearing.