The piezoelectric constitutive equation states that the inverse piezoelectric effect can convert electrical energy into mechanical energy, resulting in small displacement and force changes with high resolution. The piezoelectric actuator based on inverse piezoelectric effect has an excellent performance in active vibration suppression because of its high frequency response, high positioning accuracy, and large output force. A new active-passive composite vibration suppression system can be formed by cascading it with passive vibration isolation elements in series and parallel. On this basis, by adding different control algorithms and control loops, such as the Sky-Hook damping feedback control algorithm and adaptive feedforward control algorithm, different vibration control effects can be realized.

To improve the vibration isolation performance, a conventional passive two-parameter vibration isolator (VI) usually adopts the method of adding constant damping for energy dissipation. A compromise is made between the suppression of resonance peak and the rapid attenuation of transmissibility in the high-frequency band. A four-parameter-VI with frequency-dependent damping is a potential solution for this problem. The theoretical models of system transmissibility and equivalent damping are established by a normalization method, and the vibration isolation performance is compared with that of the two-parameter-VI and the three-parameter-VI. A novel four-parameter-VI with damping generated by a giant electrorheological fluid (GERF) damper is designed. The mechanical properties of the GERF damper are tested, and its damping effect is evaluated using an equivalent linearization method. Then, the vibration isolation performance of the four-parameter-VI is tested. The results show that: the vibration isolation performance of the four-parameter-VI can be affected by the damping ratio and the mass ratio. The four-parameter-VI exhibits the frequency-dependent damping characteristic of large damping in the low-frequency band and small damping in the high-frequency band by appropriately setting parameters. The vibration isolation ratio of the four-parameter-VI to white noise reaches 91.1% in the time domain with appropriate parameters, and the peak of the power spectral density curves decreases from 1.2e-3 g2/Hz to 0.16e-3 g2/Hz with a reduction of 1.04e-3 g2/Hz.