Too hard suspension system of a car results in throwing of the car on uneven road, while too soft suspension system will swing the car, which results in lost of the contact between the wheels and the road.

Response of the passive vibration isolation system to unit impulse excitation. Parameters of the spring and damper are chosen by such a way that the amplitude of oscillation diminishes 5 times after 2 periods of oscillation.

GIF-animation on the left shows the excitation of the system with the resonance frequency.

Response of the passive vibration isolation system to noise mechanical excitation. High-frequency vibrations are suppressed entirely. Residual oscillation occurs mainly at low frequencies.

Active vibration isolation system. Among the spring and damper there is a feedback circuit which consists of accelerometer, actuator and signal processing electronics. 

-