Bt. Wang, OPTIMAL PLACEMENT OF MICROPHONES AND PIEZOELECTRIC TRANSDUCER ACTUATORS FOR FAR-FIELD SOUND RADIATION CONTROL, The Journal of the Acoustical Society of America, 99(5), 1996, pp. 2975-2984
This paper presents an optimization solution technique to determine th
e optimal locations of piezoelectric transducer (PZT) actuators and fa
r-field microphone sensors for active structural acoustic control in c
onjunction with the use of least-mean-square (LMS) feedforward control
algorithm. A simply supported beam in an infinite rigid baffle subjec
t to an harmonically excited point force is considered. The piezoceram
ic patches are adhered to the beam and act as control transducers, whi
le microphones located in the far field are used as error sensors. The
objective function is first defined as the total radiated sound power
, The design variables which are the locations of PZT actuators and mi
crophone sensors are then identified and determined. The genetic algor
ithm (GA) incorporated with the use of linear quadratic optimal contro
l theory (LQOCT) to calculate the control voltages to the actuators is
adopted to solve the optimization problem. Results show that the opti
mally placed PZT actuators and microphone sensors can perform better s
ound radiation control than the arbitrarily selected ones. In particul
ar, for off-resonance excitation cases the optimized PZT actuators and
microphone sensors can efficiently control the sound radiation and el
iminate the control spillover. The control mechanisms of PZT actuators
and microphone sensors are demonstrated through the studies of radiat
ion directivity patterns and beam displacement distributions as well a
s the wave-number analysis. The effect of the number of microphone sen
sors are also presented. The use of optimally positioned PZT actuators
and microphone sensors can efficiently achieve structural sound radia
tion control. (C) 1996 Acoustical Society of America.