Author: Wang, Yu
Title: Analysis, design and testing of nonlinear QZS-based sensor systems for measurement of absolute vibration motion
Advisors: Jing, Xingjian (ME)
Degree: M.Sc.
Year: 2015
Subject: Vibration -- Measurement.
Nonlinear systems.
Signal processing.
Hong Kong Polytechnic University -- Dissertations
Department: Department of Mechanical Engineering
Pages: xi, 119 pages : illustrations (some color)
Language: English
Abstract: This study presents nonlinear QZS-based sensor systems for measuring absolute displacement of vibrating platforms/objects. The sensor employs quasi-zero-stiffness (QZS) theory to achieve nonlinear stiffness and one improved model which applies scissor-like truss structure (SLS) to achieve quasi-zero-stiffness is also proposed. The QZS sensor system is constructed by using positive stiffness springs and negative stiffness springs, which makes it possible to achieve equivalent QZS characteristic and consequently to create a vibration-free point for absolute displacement measurement in vibrating platforms. The improved SLS vibration sensor system is constructed by using simple beams and springs, which makes it possible to achieve nonlinear stiffness for absolute displacement measurement. Theoretic analyses are conducted and simulations are executed to evaluate the influence of structure parameters to measurement performance of the system. First, a prototype is designed which can avoid the drawback of instability in existing QZS systems with negative stiffness, and corresponding data processing software is developed to fulfill time domain and frequency domain measurements simultaneously. Then, the improved SLS sensor system is designed to achieve point-to-point vibration transmission which can limit the vibration in one degree of freedom. Both software simulations and experiment results verify the effectiveness of the sensor systems, and some comparisons are implemented to find out which system is more proper for absolute vibration motion measurement.
Rights: All rights reserved
Access: restricted access

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