Active Control of Low-Frequency Sinusoidal Vibration Transmission of Ship Machinery

Aiming at the active control of low-frequency sinusoids in ship machinery vibration, noncontact electromagnetic actuator with large output force, flat frequency response, and excellent maneuverability is developed, and the electromechanical performance of such actuator with permanent magnet bias is analyzed. A dynamic model of active-passive vibration isolation system is presented,and the factors affecting system stability are analyzed. A passive-active vibration isolator consisting of electromagnetic actuator and air spring is developed, in which a disengageable suspended structure is designed to improve its adaptability to shock and swing in the ship environment. A multi-channel narrowband Fx-Newton algorithm with rapid convergence and good robustness to frequency fluctuation is also proposed. A passive-active vibration isolation system composed of such isolators is then installed on a 200 k W ship diesel generator for testing, and the experimental results show that under complex situations such as multiple sinusoids and frequency fluctuation of the targeted sinusoids,rapid convergence of the control algorithm and stable and effective control of vibration could be realized with this isolation system. Therefore, the developed passive-active vibration isolation system can satisfactorily meet the engineering requirement of attenuating low-frequency sinusoidal vibration excited by ship machinery.