| Summary: | 碩士 === 逢甲大學 === 電聲碩士學位學程 === 105 === With the trend of industrial automation for mass production, there are many computer numerical control (CNC) machine tools which require the data collection from intelligent sensors to analyze its processing quality. In general, for high speed rotating machines, the accelerometer can be attached on the spindle to collect the data from the detected vibration of the CNC. However due to its cost, the accelerometer has not been widely adopted in typical CNC machine tool. This paper attempts to develop the embedded miniature MEMS microphone array system (5.25 cm * 8 channel) to discover the vibration source of the CNC from spatial phase array processing.
The proposed method yields the voice activity detection to divide the presence or absence of abnormal noise in the pre-stage, and the traditional direction of arrival method (DOA) via multiple signal classification (MUSIC) to isolate the spatial orientation of the noise source in the post-processing. In the numerical simulation, the non-interfering noise source location is calibrated in the anechoic chamber, and is tested with the real milling processing in vertical CNC. As the result in high background noise level, the vibration sound source is more accurate in the presented energy gradation graphs as compared to the traditional MUSIC method.
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