Modeling and control design for a controllable bearing system

This paper introduces the application of a linear-quadratic regulator to a controllable tilting-pad bearing system to reduce the vibration in a rotating machine. This application first requires a nonlinear transient simulation of the bearing to determine the stiffness and damping coefficients associated with each pad of the bearing at a given equilibrium position. The stiffness and damping coefficients are incorporated into a linear state-variable model, and a state-feedback control law is computed to minimize a quadratic performance index. The performance index parameters are adjusted to produce a suitably regulated shaft orbit in the nonlinear simulation. The results represent a significant step toward the application of feedback control to an experimental bearing system.