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SUMMARY:Feedback control of vibration in aircraft and in the ear - Profess
 or Steve Elliott\, University of Southampton
DTSTART:20120120T140000Z
DTEND:20120120T150000Z
UID:TALK35724@talks.cam.ac.uk
CONTACT:Ms Helen Gardner
DESCRIPTION:Low frequency sound and vibration inside aircraft is now atten
 uated using commercial active control systems. These typically operate usi
 ng many shakers acting on the structure to modify its vibration and hence 
 reduce excitation of the sound field.\nAs the structure becomes larger\, o
 r the excitation frequency becomes higher\, the number of actuators and se
 nsors required for effective control rises significantly. Conventional\, f
 ully coupled\, control systems then become costly in terms of weight and s
 ensitivity to individual failures. An alternative strategy is to distribut
 e the control over multiple local feedback loops\, which has been shown to
  be effective in a number of cases. Recent work will be presented on tunin
 g these local control loops to maximise the power they absorb from the str
 ucture\, which may allow the mass-production of generic active control mod
 ules that include an actuator\, sensor and self-tuning controller.\nThe wo
 rkings of the inner ear also provide a remarkable natural example of distr
 ibuted active vibration control\, whose objective in this case is to enhan
 ce the motion within the cochlea. A simple model for this cochlear amplifi
 er\, in which each of the outer hair cells act as local control loops\, wi
 ll be described and its use illustrated in predicting the otoacoustic emis
 sions generated by the ear. These emissions are used clinically to screen 
 the hearing of young children and so it is important to understand how the
 y are generated within the cochlea.
LOCATION: Cambridge University Engineering Department\, LR6
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