'Slow-active suspensions realize small switching frequencies to control low-frequency body movements,such as roll pitch and lifting motions.Fully-active suspensions reach switching frequencies,like semi-active suspensions,greater than the natural eigen-frequencies of the vehicle.'- an excerpt from a book. I have 2 questions: 1.If body roll,body pitch and lifting make-up for the low frequency body motions,what would be classified as high frequency vibration? 2.Looks like active suspensions just provide a counter force. How does having a switching frequency greater than the natural eigen-frequency of the vehicle help? Does the author mean to imply that the suspension has to think faster than the rate at which bumps come-up on the road?