OBSERVER BASED OPTIMAL CONTROL OF MR DAMPERS

Abstract

Magneto-rheological, or MR, dampers are one of the most promising semi-active control devices for protecting civil engineering structures, vehicles, ships, or aircraft from the damaging effects of dynamic loading. They have many advantages over alternative technologies, such as low power requirement, reliability, and low cost. A wide range of control schemes have been considered for MR dampers, with no general consensus on the most appropriate approach. Research at the University of Sheffield has focused on feedback linearization, but this requires measurement of the damping force which increases the complexity of the system. This study aims to overcome this problem and improve the vibration absorbability of the system by investigating the application of observer based optimal control to the force-feedback linearization of an MR damper. The proposed force-feedback linearization chose the set point force as proportional to the piston velocity. But in this study, in order improve the performance of the system, the desired set point force is chosen to be the optimal control force. The implementation of the optimal control theory requires the measurement of the system states (displacement and velocity of the mass), are provided by the observer as well. Due to passivity limitation of the MR damper the set point force is diverted to the zero at the active region to satisfy the passivity theory of Karnopp. The results of this study is compared to observer based force-feedback linearization algorithm and it is concluded that the proposed control system is able to reduce the displacement transmissibility of the damped system better then the compared one.