Active Vibration Isolation

For the active vibration isolation system the viscous damper is replaced by an actuator. Using the so-called sky-hook approach the actuator force is proportional to the absolute velocity of the mass M and the equation of motion can be rewritten as

where k is the gain factor of the feedback loop.

The transmission of the active system gets

In contrast to the passive system the transmission of the active isolation stage within the resonance

can be reduced below the value of 1 since the damping term is not affecting the numerator. For the same reason the isolation at high frequencies is not influenced by the sky-hook damping.