Varying the Stiffness of a Beam-Like Neutralizer Under Fuzzy Logic Control

Abstract

Vibration neutralizers are effective vibration control devices at a single frequency. If they can compensate for drift in the excitation frequency by adjusting their stiffness the performance can be improved, and the range of problems to which they can be applied is broadened. This paper considers a beam-like adaptive vibration neutralizer, and it is shown that the stiffness of the device and hence its natural frequency can be significantly altered by varying the beam cross-section. Several different beam configurations are investigated and the rate of change of stiffness as a function of beam separation is calculated for each configuration. The results are validated by some simple experiments. Real-time stiffness control of a beam-like tuneable neutralizer is also demonstrated both by computer simulation and experiment. The neutralizer is subjected to swept sine excitation over a six-second period and the tuned condition is maintained throughout the excitation period. The efficacy of using a nonlinear fuzzy logic controller is compared with the use of a simple proportional controller.

Adaptive Tuned Vibration Absorbers: Design Principles, Concepts and Physical Implementation

“…(Rustighi et. al., 2005, Bonello et al, 2005, Kidner et al, 2002 and similar to the percentage increase achieved by the V-Type ATVA in (Carneal et al, 2004). The main reasons for a lower-than-predicted tuned frequency as x  was reduced can be listed as follows: (a) the guide-shafts-pair and lead-screw constituting the "beam crosssection" (Fig.…”

“…This is an indication that the absorber damping a  (Fig. 1b) is low (Kidner et al, 2002). Hence, just like other types of ATVA e.g.…”

“…12, the ATVA beam is composed of two beams and the effective stiffness of the ATVA is adjusted by pushing apart the two constituent beams at the centre, thereby altering the ATVA beam cross-section. Such a device was built and tested in (Kidner et al, 2002), where a maximum adjustment of 35% in tuned frequency was achieved. This concept appears to provide the most rapid tuning of all beam-like designs in Figs.…”

“…(Rustighi et. al., 2005, Bonello et al, 2005, Kidner et al, 2002, the cosine of the phase  between the signals A y  and B y  can be used as the error signal of a feedback control system for the ATVA under variable frequency harmonic excitation (Section 4.2.2). It is noted that this result is in accordance with the two-degree-of-freedom modal reduction of the ATVA and, additionally, it could be shown theoretically that the cosine of the phase between A y  and the signal Q y  at any other arbitrary point Q on the ATVA would also be zero in the tuned condition.…”

A shape memory alloy adaptive tuned vibration absorber: design and implementation

“…In order to automatically tune the vibration absorber, a control strategy can be used, such as that proposed by Long et al [2] or Kidner and Brennan [6][7][8].…”