Driving at resonance point of multi-degree-of-freedom system by decentralized control (Excitation of natural vibration in the large degree of freedom and large damping system by local feedback control and cross feedback control)

Abstract

Driving at resonance point of the large degree of freedom and large damping vibration system is difficult because of crowd of natural frequencies and decreased peak of gain of transfer characteristics. To solve this problem, the multi-point excitation is effective. Centralized control as the general control method for multi-point excitation is the method to adjust the amplitude and frequency of all actuators and the phase difference between the adjacent actuators to suit modal shape of natural vibration. Therefore, to grasp the natural frequency, vibration mode of natural vibration is necessary. In this paper, the expansion to the large degree of freedom and large damping vibration system of the proposed decentralized control is proposed. Firstly, the difficulty of the driving at resonance point of large degree of freedom and large damping vibration system by centralized control and conventional decentralized control is explain. The self-excited vibration is generated at the frequency that has the highest peak gain of a loop transfer function. In the condition of crowd of natural frequencies, this method can excite only the particular natural vibration. Secondary, the cross feedback control is to excite the arbitrary natural vibration. The phase adjusting modal shape of natural vibration is fed back to adjacent actuator. Lastly, the adaptability for the change of damping caused by environment using damping element is verified. The influence of damping of the system in a loop transfer function is decrease by local feedback control as the active damping control. As the result, the amplitude of system maintains against the increase of damping.

Keywords

• multi-degree-of-freedom system
• decentralized control
• feedback control
• self-excitated vibration
• synchronization