Implementation and application of digitally controlled piezoelectric vibration absorbers to truss structures

Abstract

The aim of this study involves implementing adaptive PVAs by adjusting their characteristics in orbit. Specifically, the results of the study focus on the implementation of digitally controlled PVAs and demonstrate their performance in vibration control. Digital potentiometers are used to improve the ease of tuning the PVA characteristics. We derived empirical formulae to estimate the characteristics of PVAs and implemented PVAs in which natural frequency and damping ratio are designated in the microcomputer. The formulae corresponded well with the theoretical values. Additionally, we simulated the transmission of vibration to the observation equipment with the truss structure and performed vibration control experiments. The truss structure was composed of five bays. Two electromagnets fixed on the uppermost nodes excited the truss structure with a swept sine wave. Four PVAs were equipped on the lowermost nodes for vibration. We measured the mode shapes and obtained a natural frequency of 16.38 Hz corresponding to a fundamental mode such as beam bending. Based on the results, we conducted vibration control experiments under the condition with a natural frequency of 16.38 Hz and optimum damping ratio of 0.07530. The results confirmed that PVAs could reduce the peak value of frequency response at least by 2 dB. Furthermore, we derived the transfer function from the mode and natural frequency and compared this function with the experimental results. The results clearly indicated that digitally controlled PVA worked effectively and suppressed the vibration of truss structures.