A test structure has been designed to validate active control strategies aimed at reducing the vibration level on a platform connected to a noisy base structure by six stiff bars. The six bars are equipped with piezoelectric translators and force sensors. These sensor/actuator pairs-- three on each bar--are located off the bar neutral axis so that longitudinal and flexural actuation is possible. Typical excitations are due to inertial wheels, cryogenic coolers and other disturbances and can be of sinusoidal or broadband nature. Performance specification is a 40 dB reduction over the 20 - 200 Hz frequency range. Simple feedforward controllers (based on the LMS algorithm) demonstrate a potential rejection performance of more than 40 dB for a sinusoidal disturbance, validating the sensor/actuator concept. Feedback control design has to account for the very rich dynamics of the truss in the frequency band 0 - 3000 Hz, calling for robust control approaches. This design has been carried out on a simplified model of the structure, and real time implementations have been successfully achieved. A rejection of broadband disturbances of about 15 to 20 dB was demonstrated, on the 20 - 200 Hz frequency range. Simultaneous feedforward and feedback controller is possible and allows the rejection of hybrid primary disturbances.

Date Published: 27 July 1998
PDF: 12 pages
Proc. SPIE 3329, Smart Structures and Materials 1998: Smart Structures and Integrated Systems, (27 July 1998); doi: 10.1117/12.316887

Published in SPIE Proceedings Vol. 3329:
Smart Structures and Materials 1998: Smart Structures and Integrated Systems
Mark E. Regelbrugge, Editor(s)