“…Arias-Montiel and Silva-Navarro [30] investigated the use of LQR using linear actuators applied to bearings in order to control the vibration of a two-disk asymmetrical rotor system. Wen et al [31] applied LQR control method to reduce gyroscopic effect and forced vibration of magnetic flywheel rotor system. Houlston [32] proposed an extended optimal control in which the rate of change of control has been incorporated into the cost function, and compared it to conventional LQR approach.…”