Exploring capabilities of hydraulic actuators to achieve vehicle ride targets in frequency range beyond their operational bandwidth

Active suspension systems employ sophisticated control algorithms to deliver superior comfort in vehicles. However, the capabilities of these algorithms are limited by the physical constraints of actuators. Many vehicles use hydraulic actuators in their active suspension system, which use fluid movement to control suspension motion. These systems inherently have slower response times due to the nature of fluid flow and the time required to build up or release pressure within the hydraulic system. Typically, hydraulic systems operate in a low bandwidth of 0-5 Hz. This limits their capability to only meeting vehicle’s primary ride targets which typically lie below 5 Hz. Although, they can be tuned to operate at slightly higher frequency range (up to 10 Hz), they perform poorly in attenuating the secondary ride vibration, i.e., 5 – 25 Hz. This paper focuses on identifying and developing control strategies that can allow us to affect the vehicle ride well beyond the actuator bandwidth. The aim is to conduct a detailed simulation-based analysis to investigate the possibility of expanding the effective operational frequency range of hydraulic actuators. In this work, we studied force applications in the frequency range of 0 - 5 Hz with different amplitudes at four corner modules and evaluated the ride performance using standard metrics. We discovered that it is possible to improve the secondary ride performance without compromising the primary ride. Our work concludes with a discussion on the development of intelligent control strategies that could expand the horizon of conventional low-bandwidth systems.