Estimating Mechanical Vibration Period Using Smartphones

• Published in: 东华大学学报（英文版） Vol. 38; no. 4; pp. 323 - 332
• Main Authors: WANG Jiacheng, CHANG Shan
• Format: Journal Article
• Language: English
• Published: School of Computer Science and Technology,Donghua University,Shanghai 201620,China 31.08.2021; Shanghai Key Laboratory of Computer Software Evaluating and Testing,Shanghai 201112,China%School of Computer Science and Technology,Donghua University,Shanghai 201620,China
• Subjects: ridge extraction; Doppler effect; density clustering; vibration sensing
• ISSN: 1672-5220
• DOI: 10.19884/j.1672-5220.202012109

TP391; Driven by a wide range of real-world applications,significant efforts have recently been made to explore facile vibration measurement.Traditional vibration inspection systems are normally sensed via accelerometers,laser displacement sensors or velocimeters,and most of them are neither non-intrusive nor wide-spread.This paper presents a novel solution based on acoustic waves of commercial mobile phones to inspect mechanical vibration.The core observation is that the Doppler effect occurs when acoustic waves pass through a vibrating object.The study leverages this opportunity to build a bridge between the Doppler frequency excursion and the vibrating frequency of objects.The solution of difference operation of the reassignment vector is used to make time-frequency domain images more readable.Finally,by processing time-frequency images,the system further accomplishes two reconstruction approaches to find out the energy concentration of acoustic signals respectively based on ridges and clustering.Simulation and real-life applications are employed to show the effectiveness and practicability of the proposed approaches.Our prototype system can inspect the vibration period with a relative error of 0.08％.Furthermore,this paper studies two practical cases in life to associate our measurement solution with the requirements of dailv life.