The first control algorithm considered is an adaptive-passive method. A passive system can only provide isolation in the frequency range o=on > ffiffiffi 2p ; where o is the excitation frequency and on is the natural frequency. Increasing the damping coefficient in the frequency range o=onp ffiffiffi 2p willreduce the resonance peak, while the isolation performance in the frequency range o=on > ffiffiffi 2p will be degraded. Thus for harmonic vibration isolation the damping coefficient should be large