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%.

The paper describes an adaptive pneumatic suspension system that can improve both comfort and handling. Each air spring in the vehicle is connected to an auxiliary tank via two connecting pipes of different sizes. Choosing the connecting pipe with larger diameter and shorter length renders a compliant suspension which improves comfort. Conversely, choosing the connecting pipe with smaller diameter and longer length makes the suspension stiffer which favors handling. Toggling between configurations is fast, efficient, and easily done by simply opening or closing the corresponding electrovalves. The proposed adaptive system requires a GPS receiver and access to two pieces of information regarding the road at every location: the International Roughness Index and the curve radius (if not infinite). This information is used to predict road-induced vibrations and evaluate comfort with the ISO 2631 standard, as well as forecast roll angles and settling times for handling assessment. These predictions are used to select the most appropriate configuration.