In this paper, an adaptively tunable dynamic absorber is presented. The adaptively tunable dynamic absorber is a system which has tunable stiffness, which is tuned so that the natural frequency of the absorber coincides with the operating or natural frequency estimated by an adaptive algorithm. The feature of this absorber is as follows. It has an electrodynamic device for the stiffness control. Using Lorenz’s force, it changes the stiffness by changing the applied current. The change of stiffness results in the natural frequency shift, because its mass and damping coefficient are fixed. We may reduce the vibration of the overall system by tuning the natural frequency of the dynamic absorber to the resonant frequency of the structure, when the dominant single tone oscillation occurs in the system. For the estimation of the operating or natural frequency, we use an adaptive notch filter based on noise frequency estimation. Using the estimated frequency, we can reduce the vibration at the frequency which greatly influence the overall system. To demonstrate the feasibility of the proposed absorber, we reduced the vibration of a cantilevered beam excited with unknown single tone disturbance.
