Vibration Suppression of Nonlinear Reciprocating System by Control of Anti-Resonance Point

Conventional dynamic vibration absorbers cannot reduce the vibration amplitude to zero over the wide frequency range. We have proposed the control method of a semi-active dynamic absorber that can suppress the amplitude of the main system subjected to a linear restoring force to zero over the wide excitation frequency range. The proposed controller estimates in real time the varying excitation frequency by adaptive filter. According to the estimated excitation frequency, the stiffness of the dynamic vibration absorber is changed so that the main system is always excited at antiresonance point. In this paper, we show that the proposed control method for the linear system can be adaptable to the main system subjected to a nonlinear restoring force. We theoretically clarify that the nonlinearity of the main system does not affect the system in the vicinity of the antiresonance point and the amplitude of the main system even with nonlinear stiffness can be suppressed to zero over the wide excitation frequency range. Furthermore, the performance to the nonlinear system of the proposed control method is experimentally discussed.