Frequency-Selective Adaptive Control of a Hybrid Suspension System

This paper deals with a frequency-selective reference model that is used within an adaptive control structure for mechatronic vehicle suspensions. Based on a hybrid actuator configuration which consists of a slow-active actuator and a semi-active damper, the basic idea of the control approach is to emulate the dynamic behavior of a passive, but time-variant reference suspension being optimally attuned for the current driving state. The new reference incorporates the limited bandwidth of the active device in the design step and is also able to address the divergent damping demand of sprung and unsprung mass of modern vehicles. An additional potential of the resulting frequency-selective reference model of up to 25 % in comfort is revealed in comparison to the original reference without frequency-dependent properties. However, as suggested by a comparative study in terms of simulation results of a quarter-car setting based on real series suspension components this potential depends heavily on the restrictions that are imposed by the available damper characteristics.