| Popis: |
Passive systems for the isolation of equipment from base vibration involve an inherent compromise between good high‐frequency isolation, which requires low values of isolator damping, and limited excitation of the rigid body modes, which requires high values of isolator damping. It is known that a single‐channel active control system using ‘‘skyhook damping,’’ in which a secondary force acts in proportion to the absolute velocity of the equipment, can give good damping in a lumped mass‐spring‐damper system without compromising the high‐frequency isolation. In this experimental study a multichannel skyhook damper was used to study the isolation of a rigid mass from the vibrations of a flexible base plate. With the actuators and sensors wired together and the system excited symmetrically, a single‐channel controller was initially implemented which not only showed reductions in the equipment vibration of up to 40 dB at the heave resonance at 15 Hz, but also showed substantial reductions at modes of the flexible base plate below about 200 Hz. The multichannel controller was also able to control the pitching mode of the equipment which is apparent when the system is not excited symmetrically. |
