Self-Excited Driving of Resonance-Type Vibratory Machine by Vibration Quantity Feedback.

The driving system of a vibratory machine by self-excited vibration follows the resonance frequdncy change automatically and it reduces electric power consumption. The self-excited vibration is generated by positive feedback of vibration velocity or phase delay control of vibration displacement deviation on a mechanical resonance system. The amplitude of the self-excited vibration is limited by saturation of a power amplifier output. The vibration amplitude can be controlled by a variable saturation level. The frequency of self-excited vibration is equal to the phase crossover frequency on which the open loop transfer function of the system has a phase lag of 180°. The phase adjustment of the open loop transfer function realizes an agreement of the self-excited vibration frequency and the natural frequency of the vibratory machine. The self-excited vibration is suppressed quickly by switching from a feedback loop which generates self-excited vibration to a feedback loop which possesses a large phase margin.