Design of Semiactive Vehicle Suspension Controls in Frequency Domain

Through the simulation study of a semiactive quarter car suspension, this paper is to expatiate on the control algorithm documented in the United States Patent 6,873,890 [1]. That patent presents a new method to design semiactive suspension controls in the frequency domain. As is well known, suspension related dynamics has two dominant modes in the working frequency range up to 25Hz. As such, the suspension dynamic system has three distinguishable frequency sections. In order to achieve better performance, different controls have to be applied to each frequency section, respectively. The significant core part of the patented algorithm is to provide an approach to identify the excited frequencies in real time that are transmitted through the vehicle suspension. Then different controls of such as skyhook, groundhook and other damping strategies are combined accordingly to accomplish the best performance overall. Thus through the suspension control the vehicle dynamics (such as ride and handling) is expected to be improved in the broad frequency range in comparison to passive suspensions with a trade-off design.