Active noise control for motors in operating range from 200 TO 3000 RPM and noise levels around 90 dBA

La continua exposición al ruido es un mal que podría generar un efecto adverso para la salud. Sin embargo, es considerado como un efecto inherente a los procesos industriales, incluso propio de áreas comerciales en las que es difícil fiscalizar debido al alto tránsito y congestión vehicular. No obstante, en muchos casos se ha tratado de reducir sus efectos utilizando mecanismos pasivos como el uso de materiales absorbentes, los cuales, a pesar de ser efectivos en algunos casos, pueden resultar insuficientes para cancelar ruido a bajas frecuencias. Por otro lado, puede ser impráctico para zonas en las que el espacio es limitado. En busca de resolver estas desventajas, mecanismos de control activo, en los que es necesario tener fuentes secundarias de sonido, se han desarrollado para la cancelación del ruido mediante interferencia destructiva. Debido a que una segunda fuente de sonido es necesaria, dicha fuente necesitará controlarse mediante un algoritmo que pueda obtener la superposición deseada. En el presente trabajo, algoritmos de control activo de ruido son analizados, simulados e implementados. Así mismo, se presenta al algoritmo Least-Mean-Square como el más conveniente en control de ruido. Finalmente, motores eléctricos y de combustión interna dentro del rango de 200 a 3000 RPM (revoluciones por minuto), los cuales generan alrededor de 90 dB de ruido, son evaluados.Continuous exposure to noise can generate a detrimental effect in health. However, it is considered as an inherent issue on industrial processes or even on commercial areas where heavy traffic and congestion are difficult to supervise. Hence, it has been tried to be reduced through passive mechanism, such as absorbing materials, which result to be ineffective cancelling low frequencies. Additionally, it could be unpractical when there are space limitations. In order to overcome these drawbacks, active control approaches have been developed in which a secondary sources array is required to cancel the main source by destructive interference. Due to the fact that a secondary source is expected to be equal in amplitude and opposite in phase, secondary sources need a particular control algorithm to achieve the desired superposition. In this work active noise control strategies are analysed, simulated and implemented. Furthermore, adaptive algorithm Least-Mean-Square is presented as the most convenient classic control strategies. For this purpose, Diesel and Electric motors under operating range from 200 to 3000 RPM (revolution per minute) are evaluated considering noise levels around 90 dB

A systolic FxLMS structure for implementation of feedforward active noise control on FPGA

Active noise control (ANC) is an efficient technique to deal with low frequency noise that is difficult to be abated by noise barrier or sound absorbing material. Many successful ANC systems have adopted the feedforward filtered-x least mean squares (FxLMS) algorithm to reduce machinery noise. The noise canceling headset is another well known example, where the feedback control structure is favorable due to the small size. However, the feedback control structure is incapable of reducing broad band noise. Therefore, this paper investigates the feasibility of implementing the feedforward FxLMS algorithm in the noise canceling headset. Since the reference microphone has to be placed very close to the secondary source, we propose a systolic FxLMS structure that can be very efficiently implemented on the field programmable gate array (FPGA). Theoretical analysis and simulation results are presented to show the convergence behavior of the systolic FxLMS structure