A New Semiactive Variable Stiffness Suspension System Using Combined Skyhook and Nonlinear Energy Sink-Based Controllers

This paper presents the semiactive case of a variable stiffness suspension system. The central concept is based on a recently designed variable stiffness mechanism that consists of a horizontal strut and a vertical strut, both of which are semiactively controlled by magnetorheological (MR) dampers. The vertical MR damper force is designed to track a skyhook damper force, while the horizontal strut is used is to vary the load transfer ratio by semiactively controlling the location of the point of attachment of the vertical strut to the car body. The control algorithm, effected by the horizontal MR damper, uses the concept of a nonlinear energy sink (NES) to effectively transfer the vibrational energy in the sprung mass to a control mass, thereby reducing the transfer of energy from road disturbance to the car body. The analyses and simulation results show that a better performance can be achieved by subjecting the point of attachment of a suspension system, to the chassis, to the influence of a horizontal NES system.