A New Signal Processing Method Based on Notch Filtering and Wavelet Denoising in Wire Rope Inspection
Wire rope is a necessary tool in practical applications especially in crane, elevator and bridge construction, which plays an important role in the national economy and daily life, and safety inspection for wire rope is the key to ensure people’s life and property. However, detection signals are usually complicated due to the twining structures, which make the wire rope defect signal and strand signal mix together. What’s more, no reports and studies have appeared to solve this problem. In view of the situation and challenges above, this paper proposes a combined signal processing method based on notch filtering and wavelet denoising to process detected wire rope signals. Basic time domain, frequency domain and joint time–frequency analysis are first conducted, thereafter, conventional signal processing methods such as lowpass filtering and adaptive analysis are presented according to the signal characterizations. These comparisons and results demonstrate that a conventional single method is incapable of wire-rope-detection signal identification and differentiation. Nonetheless, after the notch filter design and calculation, the processing results for the typical wire rope inspection signals in the experiments indicate that the combined methods can not only distinguish steel wire rope defect signal and strand signal effectively but also with high detection accuracy, even for the inner defect. Finally, the feasibility and reliability are verified by a series of signal processing results and comparisons, which demonstrate that this new method has great application potential and is of vital significance to the development of wire rope safety inspection.
KeywordsWire rope Signal processing Notch filter Wavelet denoising Strand signal Defect signal
This paper was financially supported by the National Natural Science Foundation of China (51575213 and 51475194), the National Key Basic Research Program of China (2014CB046706) and the Fundamental Research Funds for the Central Universities (Grant No. 2015MS015).
- 5.Kalwa, E., Piekarski, K.: Design of inductive sensors for magnetic testing of steel ropes. NDT Int. 20(6), 347–353 (1987)Google Scholar
- 11.Allen, R.L., Mills, D.: Signal Analysis: Time, Frequency, Scale, and Structure. Wiley, New Jersey (2004)Google Scholar
- 12.Jomdecha, C., Prateepasen, A., Methong, W.: Characterization of wire rope defects from magnetic flux leakage signals. Thammasat Int. J. Sci. Technol. 8(1), 54–63 (2003)Google Scholar
- 19.van der Walt, N.T.: Method of and apparatus for simultaneously testing a wire rope for multiple defects. Google Patents (1993)Google Scholar
- 25.Rabiner, L.R., Schafer, R.W.: Digital Processing of Speech Signals. Prentice Hall, Upper Saddle River (1978)Google Scholar
- 27.Van Valkenburg, M.: Analog Filter Design. Holt, Rinehart, and Winston, New York (1982)Google Scholar
- 31.Schaumann, R.: Design of Analog Filters. Oxford University Press, USA (2001)Google Scholar
- 32.Thede, L.D.: Practical analog and digital filter design. Artech House Norwood, Mass (2005)Google Scholar