Patent ID: 7715949

Claim:
A vibration reducing device that reduces the vibration of a control object by a digital controller, the vibration reducing device comprising: a vibration state detection device that detects the vibration of the control object; an input-side bandpass filter, which has a passband that is narrower than a frequency range from a Nyquist frequency of the digital controller to a sampling frequency, and that contains no frequencies that are an integer multiple of the Nyquist frequency of the digital controller, and which allows the vibration that falls within the passband from the vibration detected by the vibration state detection device to pass; an A/D conversion device that converts the analog signal that has passed through input-side bandpass filter into a digital signal; a D/A conversion device that converts a feedback control signal, determined by the digital controller on the basis of the digital signal converted by the A/D conversion device, from a digital signal into an analog signal; and an actuator that applies vibration to the control object on the basis of the analog signal converted by the D/A conversion device.