A study on autonomous distributed multi-channel active noise control system

在这个研究项目中，得到了以下结果：1)首先，在时域上提出了基于联立方程法的不估计次路径的多通道ANC算法。其次，为了减少计算量，提出了一种能自动恢复二次路径变化导致的降噪效果的频域联立方程方法。在该算法中，考虑了频域处理技术——交叉谱法在联立方程法中的应用。通过将定义交叉谱法的方程直接应用于联立方程的解，无需额外的滤波器。此外，用傅里叶反变换代替了系统辨识电路。因此，加工成本大大降低。该系统的收敛速度与具有完美模型的二阶多径滤波器的滤波-x NLMS算法几乎相同。2)提出了具有多个控制器的分布式多通道ANC系统。本系统提出了一种基于联立方程方法的分布式多通道ANC系统的新实现方法。该算法允许控制器之间进行一定程度的数据交换，以提高降噪性能。在噪声消除和误差路径变化跟踪方面取得了良好的效果。然后，将该系统扩展到彩色噪声和互相关噪声的鲁棒系统。在该系统中，误差路径的估计一直在进行。仿真结果表明，该系统对误差路径的变化具有较强的鲁棒性。3)在DSP实现方面，通过实现基于联立方程法的单通道ANC算法，确定对DSP处理器的要求。其次，在DSP处理器上实现了多通道ANC算法，并验证了该算法的良好性能。少

In this research project, the following results were obtained.1) First of all, multi-channel ANC algorithm based on simultaneous equations method without estimation of secondary paths was proposed in a time domain. Next, to reduce computational burden, a frequency domain simultaneous equations method capable of automatically recovering noise reduction effect degraded by secondary path changes was developed. In this algorithm, the application of a frequency domain processing technique, the cross spectrum method, to the simultaneous equations method was considered. By directly applying the equation defining the cross spectrum method to the solution of the simultaneous equations, the additional filter becomes unnecessary. In addition, the system identification circuit is replaced with the inverse Fourier transform. Thereby, the processing cost drastically decreases. This system had almost the same convergence speed as that of the filtered-x NLMS algorithm with the perfectly modeled second … More ary path filter.2) Distributed multiple channel ANC systems which have more than one controller were proposed. This system proposes a new implementation of the distributed multiple channel ANC system based on the simultaneous equations methods. In the proposed algorithm, some exchanges of data between controllers are permitted to improve the performance of noise reduction. The good performances for noise cancellation and tracking of the changes in the error paths were obtained. Next, this system was extended to the robust system for colored noise and noises having cross correlation. In this system, the estimation of error paths was executed at all times. As a result, this system was also robust for the changes of error paths and showed sufficient results though simulation results.3) For DSP implementation, requirements for DSP processors were confirmed through the implementation of single channel ANC algorithm based on simultaneous equations method. Next, multi-channel ANC algorithm was realized on DSP processors and the good performance of the proposed algorithm was verified. Less