Amplitude Control Using Variable Feedback Gain in Self-Excited Driving Vibratory Machine.

The driving system of a vibratory machine with self-excited vibration follows the resonance frequency change automatically, and reduces electric power consumption. Self-excited vibration is generated by the positive feedback of vibration velocity or the phase delay control of vibration displacement deviation on a mechanical resonance system. The self-excited vibration whose amplitude is limited by saturation of a power amplifier output contains many higher-harmonic components. On the other hand, the self-excited vibration whose amplitude is limited by variable feedback gain becomes a pure sine wave. The feedback gain is controlled by amplitude deviation. The controller consists of a constant term, which is equal to the critical gain on the stability of the feedback system, a linear term and a third-power term of amplitude deviation. The constant term and the linear term influence the steady-state vibration, and the third-power term influences the rising characteristics of vibration.