Development of the passive-active vibration absorber using piezoelectric actuators

This paper is concerned with the development of the passive-active vibration absorber using piezoelectric actuators. The active vibration absorber system consists of 2 pairs of PZT actuators bonded on aluminum plates making s- shaped device. Hence, the active system is directly connected to the passive system. The rubber attached to the end of the beam is connected to the upper base as a structural member. It allows bending thus maximizing the vertical movement generated by the piezoceramic actuators. This paper also presents the development and the verification of the control techniques for the passive-active vibration absorber. The vibration absorber can be utilized as a passive vibration absorber when the controller is off. It is shown that vibrations can be reduced by 20dB for the first mode, when the SISO PPF controller is operated. The advantage of PPF controller provides us the most effective way of increasing damping for the particular mode of interest. However, the natural mode should be computed in the process of design, to maximize the performance. In reality the target natural frequency is estimated by the frequency response of the vibration-absorbing device and is later applied to the PPF controller as a filter frequency. In this paper, the adaptive PPF controller is considered to cope with the structural change, so that it can modify the filler frequency based on the measurement. It is found that the adaptive PPF controller is effective for the active vibration absorber when the external disturbance is applied with various excitation frequencies. It can be concluded that the proposed passive-active vibration absorber is an effective way of reducing the vibration amplitude of the precise devices in the harsh environments thus enhancing the precision.