Adaptive control of active tilting-pad bearings

A promising mechanical bearing candidate for active operation is the tilting-pad bearing. The active tilting-pad bearing has linear actuators that radially translate each pad/pivot pair. The use of feedback control in determining the actuator forces allows for the automatic, continuous adjustment of the pad position during the operation of the rotating machine. In this paper, we first develop the full-order dynamic model of the active bearing system such that the actuator forces are the control inputs. The hydrodynamic force produced by the lubricant film is modeled as a linear spring-damper with unknown damping and stiffness coefficients. An adaptive feedback controller is designed to asymptotically regulate the rotor displacement, despite the uncertainties in the coefficients of the lubricant force. High-fidelity simulation results show that the proposed adaptive controller significantly improves the bearing performance in comparison to the common passive operation.