A semi-active vehicle suspension based on pneumatic springs and magnetorheological dampers

Abstract

Semi-active and active suspensions can improve both ride comfort and handling compared to passive suspensions. The authors have proposed a suspension comprising a pneumatic system capable of changing the stiffness of the suspension and a semi-active magnetorheological damper capable of controlling the suspension damping. Eight configurations of this magnetorheological/pneumatic suspension result from combining two possible stiffnesses (compliant and stiff) and four possible means of producing damping (constant low, constant high, on-off skyhook control and on-off balance control). The minimization of a cost function, which considers both ride comfort and handling, leads to decision maps which indicate the most appropriate configuration depending on vehicle velocity and two pieces of information about the road: the international roughness index and the curve radius. All this information can be gathered from a GPS system and toggling between set-ups is fast, efficient, and easily done by simply opening or closing pipes in the pneumatic system and modifying the current supply in the magnetorheological dampers. The proposed magnetorheological/pneumatic suspension achieves the same roll angle levels as in a comparable passive vehicle while improving ride comfort by reducing acceleration by up to 30%.

How do driving modes affect the vehicle’s dynamic behaviour? Comparing Renault’s Multi-Sense sport and comfort modes during on-road naturalistic driving

“…Active suspension components enable online changes of the stiffness and damping settings. Current commercialised vehicles utilise variable damping in combination with passive springs but typically do not use variable stiffness, a concept that is currently in a research phase [36,44,45]. Besides variable damping and stiffness, active suspension mechanisms can apply control strategies to minimise the impact of braking and cornering on the body (active body control, active roll control) and to compensate for road irregularities [30,46,47].…”

Investigation on linear quadratic Gaussian control of semi-active suspension for three-axle vehicle

“…6 Hence, semiactive suspension featuring high performance and low-power consumption has progressively turned into a focus of research. [7][8][9][10][11] Maciejewski proposed an active seat suspension with pneumatic muscles, results showed that a significant reduction in vibrations transmitted into the human body can be acquired by a slight increasing of the suspension travel [7]. In [9], a novel control strategy was applied to the horizontal seat suspension system, harmful vibrations transmitted to the driver in a wide range of excitation frequencies could be reduced.…”

“…10 The application of GPS system into MR/pneumatic suspension control is proposed by Morales, achieved the same roll angle levels as in a comparable passive vehicle while improving ride comfort by reducing accelerations up to 30%. 11 The control strategies commonly used for semi-active suspension include optimal control, 10,[12][13][14] skyhook control, 15,16 sliding mode control, 17,18 fuzzy control, 19,20 and PID control, 21,22 etc. Skyhook control and sliding mode control exhibit certain robustness, but they are not designed to realize the optimal system performance.…”

A Hydraulic Semi-Active Suspension Based on Road Statistical Properties and Its Road Identification

“…For vehicles under different road conditions, the focuses of ride comfort and handling stability are different [3][4][5]. The damping characteristics of semi-active suspensions should also be changed along with the road conditions [6,7].…”