Some characteristics of optimal vehicle suspensions based on quarter-car models

This study addresses the main characteristics of optimal active automobile suspension based on two degree-of-freedom quarter-car vehicle models and associated global performance maps. In addition, the authors put into perspective the optimal active suspension performance through comparison with passive counterparts. It is shown that, in general, stiffer active suspension with more damped wheel-hop mode will result for very rough roads and/or high speeds. Moreover, the same suspension control gains could result from different roads and/or speeds, depending on, for example, road curvature. The passive counterparts, on the other hand, cannot in general, reproduce the same level of performance. Even where the active and passive RMS performances are similar, the active suspension results in faster and much better damped sprung mass modes, substantially reducing sprung mass motion induced by various cornering and acceleration/braking maneuvers