This paper describes the hydraulic active suspension which is mounted in the Nissan Infiniti Q45 and is effective in improving high-speed safety. This active suspension has been designed specifically to provide improved vehicle stability at high speed through the use of skyhook damper control, a frequency-dependent damping mechanism and active roll and pitch control. The system design concept is presented along with an analytical explanation of the three major functional features. The results of theoretical and experimental analyses clarify quantitatively: (1) the effects of the control procedures and parameters on both the vertical vibration characteristics of the vehicle body during high-speed driving, and (2) on the road contact of the tyres when traveling on an undulating road; (3) crosswind stability; and (4) steering response characteristics. The results confirm that this active suspension provides outstanding performance unobtainable with conventional suspensions, especially under high-speed driving conditions. (A)
Abstract