| 摘要 |
PURPOSE:To precisely control external vibration in a short time by damping vibration with large amplitude by means of both a variable spring and a variable damping device, and executing active control thereafter in such a way that vibration is changed into small displacement in vibration with a piezo- actuator driven when vibration amplitude becomes less than specified one. CONSTITUTION:A table 4 for the installation of precision instruments is supported over a foundation 1 by the use of a piezo-actuator 5 using piezo-electric elements, a variable spring 2 and a variable damping device 3. Both of the variable spring 2 and the variable damping device 3 are controlled by a control device 8 in response to signals from a detector 6 for coarse motion, which is provided over the table 4, and the piezo-actuator 5 is diven by a control device 9 in response to signals from a detector 7 for micro-motion. When external vibration is applied to the foundation 1, vibration is damped first by a passive or a semi-active control mechanism. In this case, the control device 9 is out of action, the control device 9 however is not allowed to be in operation before the vibration amplitude of the table 4 becomes 100 mum and less, micro- vibration is therefore damped by means of active control. |
