Vibration control of a structure by using a tunable absorber and an optimal vibration absorber under auto-tuning control

Vibrations of machines and structures vanish perfectly at a certain frequency when they have a vibration absorber without damping. But if forced frequencies vary from the anti-resonance frequency, their vibration amplitudes increase significantly. Then the absorber without damping cannot be applied to the structure subjected to variable frequency loads or the loads having high-frequency components. The present article discusses a method of vibration control of a structure by using the vibration absorber without damping. In this method, a variable stiffness vibration absorber is used for controlling a principal mode. The stiffness is controlled by the microcomputer under the auto-tuning algorithm for creating an anti-resonance state. The optimal vibration absorber with damping is also utilized for controlling higher modes. The analyses and the algorithm for the auto-tuning control are developed. A method to obtain optimal parameters has been presented for the vibration absorber which controls higher modes. In order to validate the control method and the analysis, experimental tests have been carried out. (C) 1999 Academic Press.