Yoichi Kanemitsu

Vibration damping apparatus

A vibration damping apparatus has a vibration-isolating table for placing an object thereon which is to be isolated from vibrations, an air spring mounted on an installation floor and supporting the vibration-isolating table for attenuating vibrations from the installation floor, an air pressure controller for controlling an air pressure of the air spring, a displacement sensor for detecting a relative displacement between the vibration-isolating table and the installation floor and supplying a signal indicative of the detected relative displacement to the air pressure controller, and a spring element acting between the vibration-isolating table and the installation floor for positioning the vibration-isolating table horizontally. An electromagnet is disposed between the vibration-isolating table and the installation floor for actively attenuating vibrations of the vibration-isolating table. The vibration damping apparatus is operated to position the vibration-isolating table horizontally by means of the spring elements, and vertically by means of the air spring.

Active Control of a Flexible Rotor by an Active Bearing

This paper details the effects of analog and digital compensation circuits used when passing through critical speeds of a flexible rotor suspended by an active magnetic bearing. Several kinds of filters are used for rotation tests and vibration characteristics of the rotor are measured. A digital IIR filter implemented by a DSP could attenuate the vibration of the rotor at critical speeds.