An Air Suspension System With Adjustable Height, Damping and Stiffness Using No Viscous Dampers

Air suspension is gaining more and more popularity with both the auto industry and drivers. Traditionally the height adjustability aspect of air suspension systems has been their main attracting attribute. More recently, resolving the classic conflict of combining comfortable ride with sport handling in a single suspension setup has become the main attraction of air suspension. An air suspension system has been developed which in addition to height adjustment, can adjust its damping and stiffness in real time with using neither viscous dampers nor any additional actuators. This is done by real-time adjustment air flow to and from the air springs using proportional valves. Measured relative displacement and acceleration as well as estimated velocity of the sprung mass with respect to unspring mass at each corner are fedback, thru their corresponding gains, to create the control signal that adjusts the proportional valve with the goal of controlling the height, stiffness, and damping at that corner. In a numerical study followed by laboratory testing, the effectiveness of the proposed air suspension system in terms of its ability to vary the damping and stiffness as well as the height of the suspension system is demonstrated.