An Active Vibration And Noise Controller Based On An Embedded UC/OS-? Real-time Operating System

An increasing attention has been paid to reducing aircrafts cabin noise, due to the requirements for passengers' comfortableness. The traditional passive noise reduction method has limited effect while the active noise control technique draws more attention according to obvious noise reduction effect. At present, the common active noise control system is generally low integrated or single-function. Therefore, a particular system with high level of integration, fine stability, outstanding scalability and multiple function will have great application prospect in the field of active noise control. Aiming at controlling vibration and noise actively, a real-time controller was designed based on an embedded real-time uC/OS-III operating system. The specific work includes: 1, a requirement analysis on active noise control system is carried out, and then the overall design scheme of the system is put forward with an analysis on the feasibility of the scheme of hardware and software. 2, As with the hardware, the design includes a minimum system based on STM32F407 chip, a sampling unit based on AD7606 chip and a digital to anolog conversion unit based on DAC8563 chip, a network communication unit based on DM9000 chip, and a display unit based on RA8875 chip. 3, As with the software, a second-order controller for active noise control system is designed, together with a graphic user interface(GUI) using STemWin, a TCP/IP server application unit based on uIP protocol stack, an uC/OS-III based program framework and an upper computer control-monitoring program based on microsoft foundation classes(MFC). 4, An experiment is made to verify the real-time performance of the controller, and another one on aluminum plate is done to verify active noise reduction effect of the controller by using a ported and optimized algorithm named NAF( the acceleration negative feedback).This system implements seven functions including real-time data acquisition through 4 channels with 20 Ksps sampling rate, signal processing preceding, digital to anolog conversion, real-time communication with PC via Ethernet, key parameters saving and restoring automatically, friendly human machine interface, and upper computer dialog box program. This system can meet the demand for active noise control applications and with advantages of high integration, strong real-time performance, good stability and rich function.