Semi-active suspensions with low-order mechanical admittances incorporating inerters

This paper investigates the application of inerters in semi-active suspensions. An approach to designing semi-active suspension with inerter is proposed by dividing the semi-active system into a passive part and a semi-active part. The passive part is a mechanical network consisting of springs, dampers and inerters; the semi-active part is a semi-active damper. Different from the existing result using some fixed-structure networks as the passive part, in this study, the passive part is obtained by optimizing some low-order admittance functions and then by realizing the optimized admittance functions as mechanical networks. A suboptimal control law named steepest gradient control is employed for the semi-active damper in the semi-active part. The proposed method is illustrated in a quarter-car vehicle system, and the effectiveness of the proposed method is demonstrated by using numerical simulations. It is shown that significant improvement can be obtained by using the proposed method compared with the conventional semi-active suspensions without inerter.