Thisis the second of three companion paperst hat summarize the theoretical and experimental work carried
out to develop a prototype smart panel with 16 decentralized vibration control units for the reduction of
sound radiation/transmission. In this paper the design and implementation of the 16 decentralized control
units is discussed. Each control unit consists of a collocated accelerometer sensor and piezoceramic patch
actuator with a single channel velocity feedback controller in order to generate active damping.
The design and implementation of a single control unit has been discussed first. The frequency response
function of the sensor–actuator pair has been measured and compared with the results of a computer
simulation in order to investigate the effects of accelerometer dynamics, and actuator size. Since the system
is only conditionally stable, a phase lag compensator has then been designed so that larger control gains
that guarantee stability could be implemented.
The single-channel controller has then been implemented on each of the 16 decentralized control loops in
the final system. The stability of the final control system has been assessed by plotting the 16 eigenvalues
loci matrix product between the open loop sensors–actuators frequency response matrix and the diagonal
matrix of control functions (fixed control gains multiplied by the phase lag compensators). None of the loci
encircle the Nyquist point (1,0) asthe frequenciesva riesfrom N to +N at moderate gains, although
part of the locus occupies the left hand side of the plot. Thus the complete control system is stable only for a
limited range of control gains.
The control effectiveness of both the single control unit and 16 decentralized control units has been
assessed by plotting the velocity at one error sensor with reference to either an acoustic source in the cavity
(loudspeaker) or a primary point force on the panel (shaker).
