Abstract
A control method has been developed to always excite a multi-degree-of-freedom system efficiently at a resonance frequency. When an excitation point corresponds to a vibration detection point in the multi-degree-of-freedom system, a phase lag at a resonance frequency and a phase lead at an anti-resonance frequency alternately appear in the vibration characteristics, and the phase lag becomes 90° at all the resonance frequencies. Therefore, if a controller that has a phase lag of 90° and a constant gain in a wide frequency range is used, self-excited vibration is generated at all the resonance frequencies. The self-excited vibration mode in the multi-degree-of-freedom system with local feedback control can be freely switched by dynamic stimulation. However, it can be also disadvantage in the point of changing against the desire. In this paper, a cross feedback control is added to the local feedback control to excite and stabilize the self-excited vibration modes. The cross feedback control mutually exchanges control signal between adjacent local feedback controllers. Giving the sign of the cross feedback gain corresponding to natural vibration modes can assist formation of the self-excited vibration modes. At first, we verified all the natural vibration modes are excited by adding cross feedback control. Additionally, we verified the desired natural vibration can be maintained against a disturbance. Finally, we verified amplitude of the vibration is maintained against changing mass and dumping.
