PD-Skygroundhook Controller for Semi-Active Suspension System Using Magnetorheological Fluid Dampers

This paper presents a Proportional-Derivative (PD) Skygroundhook controller for magnetorheological (MR) dampers in semi-active suspensions. Traditional skyhook, Groundhook, and hybrid Skygroundhook controllers are well-known for their ability to reduce body and wheel vibrations; however, each approach has limitations in handling a broad frequency spectrum and often relies on abrupt switching. By adding a derivative action to the classical Skygroundhook logic, the proposed PD-Skygroundhook method enhances high-frequency damping and stabilizes transition behaviors. By leveraging the fast response of MR dampers, our controller adjusts the damper force continuously in real time to match the desired damping force of PD-Skygroundhook controller with efficient computation. Experimental evaluations under bump excitations and sine-sweeping tests demonstrate a significant reduction in sprung mass acceleration and unsprung mass acceleration, outperforming standard Skygroundhook in both ride comfort and road handling. These results highlight that the derivative action effectively reduces resonance peaks and smooths out force transitions of regular Skygroundhook. Our method offers a robust alternative to more computationally demanding semi-active controllers.