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 a 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 investigating the possible hardware and subsequently control capabilities 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 Fast Fourier Transformation (FFT). This paper concludes with a discussion about the extent of Hydraulic Actuator limitations and the required technological advancements for improving the secondary ride response.