The Study on the Active Control of Acoustic Fields in Duct by using PID Controller

This thesis is to study the active control of acoustic fields in duct. There are two parts for the experiment. Firstly, we find the mathematical models of the acoustic path and the control system path by using the modeling method. Secondly, we design controllers by system models.
There are two frameworks for the controllers. The first one uses the signals received directly from the function generator as the reference input. A feedforward control by Dominant Pole Assignment algorithm is used to produce the optimum interferential output. The result reveals the attenuation of the acoustic pressure and associated power just downstream the controllable source for pure-tone by 20 to 25 dB and 20 dB can be achieved.
In the second one, we study ANC based on a robustly feedback-controlled secondary path.. A robust feedback controller for the secondary path is obtained by increasing Gain and Phase Margin. The result reveals the attenuation of the acoustic pressure and associated power just downstream the controllable source for pure-tone by 10 to 15 dB and 10 dB can be achieved.