홀 센서를 이용한 와이어 로프 결함 자속누설검사 시스템의 개발 및 결함 측정 신호의 분석 = Development of a Magnetic Rope Testing System Using Hall Sensors and Its Wire-Break Signal Analysis

국문 초록 (Abstract)

와이어 로프의 내부 단선 검출 성능을 향상시키기 위해 이전 연구에서 개발된 Magnetic Rope Testing (MRT) 시스템을 개선하였다. 개량된 MRT 센서는 16개의 홀(Hall) 센서를 사용하여 와이어 로프의 결함에 의해 반경 방향으로 누설되는 자속을 측정하도록 제작되었다. 측정된 홀 센서 신호를 채널마다 위치별로 평균화하고 이동평균을 통해 신호의 상하 변동을 보정한 후 전체 신호의 root-mean-squared (RMS) 값의 2배를 초과하는 신호를 결함으로 판별하는 기준을 적용하여 1차적인 결함 검출을 수행하였다. 이러한 이동평균만으로검출이 어려운 미세한 결함 신호는 이산웨이블릿변환(DWT) 기반의 잡음제거 기법을 추가 적용하여 판별할 수 있었다. 결함 검출을 위해서 이동평균의 윈도우 폭과 잡음제거 수준의 최적값을 결정하는 실용적인 방법을 도출하였다. 실제 와이어로프 검사 현장에서 개선된 MRT 센서의 성능 시험을 수행하였고, 측정된 신호에 대해 RMS 2배 기준 결함 검출과 DWT 잡음제거를 병행하여 결함 검출능이 향상되었음을 확인하였다. 향후 연구에서는 MRT 센서의 감지 성능을 더욱 향상시켜 해외 장비를 대체할 수 있는 수준의 검사 장비 개발을 목표로 하고 있다.

다국어 초록 (Multilingual Abstract)

In this study, we improved a previously developed magnetic rope testing (MRT) system to enhance the detection performance of internal wire breaks in wire ropes. The improved MRT sensor was designed with 16 Hall sensors to measure the radial magnetic flux leakage caused by defects in the wire rope. The measured Hall-sensor signals were averaged by position for each channel and corrected for signal drifts using a moving average. Twice the root-mean-squared (RMS) value of the entire measured signal was used as a threshold criterion for primary defect detection. For subtle defect signals that could not be detected with moving averages alone, the discrete wavelet transform (DWT) denoising technique was applied. A practical method was developed to determine the optimal moving-average window width and denoising level for defect detection. Actual field tests of wire ropes were conducted to evaluate the performance of the improved MRT sensor, and the results confirmed that the defect detection performance was enhanced when both the RMS double threshold and DWT denoising methods were employed. Future studies will be focused on further improving the sensing performance of the MRT sensor to develop equipment capable of replacing foreign technology.

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