| As the social living standards rising, the noise attracts more and more public attention. The Active Noise Control (ANC) technology has been proposed on1930s for the first time. Due to the speed of hardware, the ANC has not been widely used. With the improvement of digital signal processing and adaptive filtering technique, the utility of ANC is gradually increasing. The NI cRIO is selected for the development of the ANC prototype system, because the platform has the advantages that the input and output ports can be configured, the real-time operation is fast and it is easy to develop.In this thesis, the ANC algorithms and the structure of the control system were introduced and studied deeply, the advantages and disadvantages of the FXLMS algorithm and the active filtering algorithms of single multi-channel under different conditions are analyzed and compared. Other algorithms including LMS, RLS, Lattice, Subband, FLMS, and so on are also discussed.The ANC algorithms have been simulated to analyze the role of the step sizeμto the stability and convergence with the Simulink and LabVIEW software. The comparative study between the weights of the adaptive filter algorithm and impulse response from the measurement shows that the algorithm is reasonable. Using the hybrid simulation model of experiment of numerical simulation, the feed forward and feedback ANC algorithm, which can be used to reduce the noise in the duct, are validated.Based on hybrid ANC algorithm, the platform of NI cRIO (FPGA) hardware and software and the FPGA module and real-time module of the LabVIEW, we established two typical experimental ANC systems: the duct and the space point source. For the point source system, the single frequency noise achieved more than 3dB noise reduction between the 200Hz and 1000Hz; for the duct system, white noise obtained more than 10dB noise reduction and the single-frequency noise can achieve more than 17dB noise reduction between 200 Hz and 1000Hz. |
PDF Full Text Request