Research on control strategy of an active magnetorheological fluid bearing based on improved gray wolf optimization approach

In order to address the problems of insufficient load capacity and rotor vibration, an active fluid-film bearing lubricated with magnetorheological fluid (MRF) is proposed. First, the geometry of the MRF fluid-film bearing is designed and its intelligent lubrication mechanism is analyzed to clarify its advantages. In addition, mathematical model of MRF fluid-film bearing-rotor system is derived, and FEM model is utilized to obtain stiffness and damping coefficients to supplement mathematical model. Moreover, an improved gray wolf optimization (IGWO) algorithm is developed to tune the PID controller parameters. The validity of the proposed method is verified by numerical simulation. Furthermore, the simulation results show that with the increasing of current magnitude, the orbits of shaft center decrease. Under the presence of magnetic fields, the shaft center orbits of the MRF bearing can converge to a point, and therefore this bearing has ability to suppress rotor vibration. Finally, IGWO-PID controller has better response characteristics than GWO, PSO, and GA algorithms, and hence the IGWO algorithm can find the more appropriate PID controller parameters, that the validity of the improved algorithm is further proved. Therefore, the active bearing and its research findings provide new reference for MRF vibration control in the field of journal bearing lubrication.