Abstract:

The feasibility of using active control to reduce the low frequency transmission of vertical, lateral and rotational vibration through an existing passive isolation system is investigated numerically and experimentally. The work involved the use of vibration actuators attached to the intermediate mass of a two-stage mount, in parallel with passive isolators, to minimize the vibratory energy transmission of the intermediate mass to a receiving structure. The maximum achievable control was determined by measuring the vibration level at the error sensors due to the primary vibration source and measuring the transfer functions from the control sources to the error sensors. The control performance was numerically evaluated at a set of monitor sensors. Results show that over a low frequency range from 10 to 100 Hz, the power transmission into the intermediate mass can be reduced substantially by employing active elements with existing passive isolators. The results also demonstrated the effectiveness of intermediate mass control in increasing the overall low frequency vibration isolation offered by the mount.