Semi-Active Dynamic Absorber Using the Fuzzy Theory for a Beam Subjected to Moving Loads.

Abstract

This paper presents a semi-active dynamic absorber for controlling the vibration of a beam subjected to moving loads. The eigenvalues of the beam system containing moving loads vary according to position and number of loads on the beam. The eigenvalues of the semi-active dynamic absorber are also adjusted to those of the beam system. The proposed semi-active dynamic absorber is of cantilever type and the absorber mass is moved to adjust the eigenvalues. It is difficult to estimate the characteristics of the beam system, which depend on the moving loads. The fuzzy control theory has robustness for uncertain systems. Therefore, the movement of the absorber mass is determined by fuzzy inference. In this paper, the adjustment of absorber mass to the position, which is determined by the displacement responses of the beam, is performed by the fuzzy controller. It is important to decide the control rules in the fuzzy control algorithm. The rule table is produced by the simulation of analytical models. The dynamic responses and spectra of displacements at the mid-point of the beam are shown in various cases. The effectiveness of the semi-active dynamic absorber is demonstrated experimentally.