Abstract
Experimental investigations into active control of bandlimited noise transmitted into the interior of a three-dimensional enclosure with a flexible wall are presented. In the different experiments, the frequency range of the bandlimited disturbance is chosen to encompass structural and/or enclosure resonances. The rigid boundaries of the enclosure are constructed from acrylic material, and the flexible boundary clamped along all the edges is constructed from aluminum material. Lead Zirconate Titanate (PZT) patches mounted symmetrically on the flexible wall are used as actuators. Polyvinylidene fluoride (PVDF) film patches mounted on the flexible wall are used as vibration sensors, and condenser microphones placed inside and outside the enclosure are used as acoustic sensors. Digital feedforward control schemes based on filtered-x gradient descent algorithms are implemented in the experiments to minimize a chosen performance function. Different performance functions are examined, and the results obtained in the corresponding cases are compared. It is observed from the experiments conducted thus far that better noise reduction results are obtained when only acoustic sensors are used than when either vibration sensors or a combination of acoustic and vibration sensors is used.
