Numerical and experimental study of an active control logic for modifying the acoustic performance of single-layer panels

This work proposes an active control logic that uses a linear quadratic regulator (LQR) controller and a Kalman-Bucy (KB) state observer to improve the acoustic performance of single-layer panels. When the panel is subjected to an acoustic excitation, the proposed strategy can automatically adapt to the acoustic disturbance by tuning some of the decisive weighting factors in the LQR and the KB filter according to the spectrum of the signals from sensors. This control acts on the panel with PZT patches as actuators and accelerometers as sensors, forming a smart structure. The vibroacoustic model of the smart panel is formulated using modal functions, from which the transmitted power and the transmission loss of the panel are derived. Accordingly, the control strategy is designed using the state-space representation under modal coordinates, during which the spillover effect is considered and the placement of actuators and sensors is optimized by a modified modal H2 norm approach. It is noticeable that several advanced techniques in the active control of noise and vibration are implemented in this development of the smart panel. Following this, numerical and experimental studies oriented to the effectiveness of the proposed control logic are performed. While the numerical simulations are carried out under the assumption that the two sides of the panel are a reverberant and a free field, respectively, the experiments are conducted using the test equipment called Noise-Box, whose inner space is considered able to simulate a field incidence. Two scenarios are provided: one for the monotone at 500 Hz or 1,000 Hz; the other for the white noise within 750 Hz – 1,000 Hz. The results validate that the active control improves the acoustic performance of the panel for sound insulation, whether the acoustic disturbance is a monotone of any frequency or a band-limited noise with a given frequency range.