Abstract
In recent years, semi-active suspensions have been widely used in order to improve ride comfort of automobiles taking advantage of less energy and cost. This study aims at achieving simultaneous realization of ride comfort and steering stability in the controller design for semi-active suspension considering the most sensitive frequency range of human body and vehicle behavior for steering. In this study, an algorithm which can improve both the ride comfort and the steering stability is proposed by separating the control range in terms of frequency domain. In consideration of the above concepts, the frequency weightings and the criterion function are designed in frequency domain. Furthermore, the controller is scheduled in time domain in order to realize the positive pitch angle mode at the slalom. In this study, the dynamics of road disturbance is supposed and is accommodated into that controller to make the control performance more effective. In order to investigate the effectiveness of the proposed control system, simulations are carried out by using a full vehicle model which has variable stiffness and damping semi-active suspension system. As a result, it is demonstrated that the proposed method can realize improving the ride comfort, reducing the vehicle attitude change, and synchronizing the roll and pitch angle caused by steering.
