**6. Conclusions**

In this chapter, the active vibration suppression of an active-passive composite vibration suppression system based on piezoelectric actuators is studied. On the basis of fully analyzing the characteristics of piezoelectric actuator and displacement amplifying mechanism and the dynamic model of vibration suppression system, an active composite control strategy based on IFF and RLS adaptive feedforward for vibration suppression on the piezoelectric system is discussed. The experimental results show that using the active control method, the vibration suppression system based on piezoelectric actuator has not only lower natural frequency, wider active vibration suppression bandwidth, but also reduces the value of the resonance peak, and maintains the attenuation rate at high frequency. Therefore, piezoelectric actuators are a good choice for vibration suppression, especially active vibration suppression.
