Speed adaptation of a rotational pendulum vibration absorber

The rotational pendulum absorber (RPA) has the flexibility of an active vibration absorber and the energy efficiency of a passive device. In this paper on-line adaptation of the rotational speed is explored. The objective is to automatically tune the rotational speed of the RPA in order to minimize the vibration of the primary structure which is subject to a harmonic disturbance of uncertain frequency. The nominal speed of the RPA is adjusted according to the measured phase angle between the acceleration of the primary structure and the acceleration of the pendulum absorber. It is shown that convergence of the nominal speed depends on the relative magnitude between the initial value and the excitation frequency. The allowable ranges of the initial value of speed versus excitation frequency are derived. Effectiveness of the adatation scheme is verified by real-time experiments.