Measurement of micro-harmonic vibration frequency from the modulated self-mixed interferometric signal using dynamic time warping method

• Published in: Mechanical systems and signal processing Vol. 168; p. 108712
• Main Authors: Bhardwaj, Vibhor Kumar, Maini, Surita
• Format: Journal Article
• Language: English
• Published: Berlin Elsevier Ltd 01.04.2022; Elsevier BV
• Subjects: Algorithms; Biomedical engineering; Biomedical materials; Dynamic time warping algorithm; Euclidian distance; Frequency measurement; Interferometry; Nondestructive testing; Optical feedback; Predictive maintenance; Reference signals; Reverse engineering; Self-mixed effect; Vibration frequency measurement; Vibration measurement; Warping; Dynamic time warping algorithm; Optical feedback; Euclidian distance; Vibration frequency measurement; Self-mixed effect
• ISSN: 0888-3270; 1096-1216
• DOI: 10.1016/j.ymssp.2021.108712

•The paper presents a method to measure the micro-harmonic vibration frequency.•The method is verified on a customized SM-OFI setup under weak feedback conditions.•Method computes Euclidian distance between reference and obtained interferometric signal..•Method exhibits 98% accuracy with 0.99 R-squared value and relative error less below unity. The vibration frequency is one of the key factors that contains vital information about the subjects/machines and offers major analytical support. The contactless measurement of vibration frequency is the crucial requirement of many industrial, scientific, and biomedical applications like predictive maintenance, non-destructive testing, and reverse engineering, chest vibration, etc. The paper presents a self-mixed optical feedback interferometry (SM-OFI) sensor to measure the vibration frequency of the micro-harmonic vibrating surface. The method employs a Dynamic Time Warping algorithm (DTW) to compute the Euclidian distance between the locally generated reference signal and the SM interferometric signal obtained from a vibrating target. The method is tested experimentally on a customized SM-OFI emitting a wavelength of 650 nm under weak feedback conditions. The proposed method was able to measure the unknown frequency with 98% accuracy in all sets of experiments. The method also exhibits an R-squared value of 0.99 with a relative error of less than unity. The comprehensive analysis of the experimental results concludes that the proposed method provides an accurate and precise vibration frequency measurement scheme for the low bandwidth range. This low bandwidth range measurement promises a non-contact measurement in industries and biomedical applications during the COVID-19 scenario.