The estimation of modal parameters of structures using the subspace identification algorithm of the descriptor state space systems
Date Issued
2009
Date
2009
Author(s)
Hsu, Kuo-Hsiang
Abstract
Structural system has its own unique characteristics, which can be abstracted from the interdependence between its input-output information. Measuring the dynamic input and output information of a system to evaluate the associated characteristics can establish the mathematical model required to identify the system. Regarding to the structural system identification procedure, in addition to the second-order matrix differential equations to describe the characteristics of its structure, it can be a first order matrix of differential equations. A first order matrix of differential equations can be one of infinite types. This study propose descriptor systems to set up a first order matrix of differential equations, and further to extend subspace algorithms of descriptor state space systems to identify the structure of system. One type of subspace algorithms is obtained to get descriptor systems from input to output information and further to identify the damping ratio of stucture, its natural frequency, model shape and associated system matrix.n addition to verify the descriptor systems can effectively to free and force vibrations, this study is to use both the acceleration measurement for the system of three degrees of freedom and adding of different signal noise ratio to test the capacity of descriptor systems anti-noise. In order to reduce randomly scattered volatility resulting form an unknown noise, it is to perform Monte Carlo simulation for 1024 times. Finally, it is to discuss three cases, which respectively are cantilever steel beam, impact motorcycle structure and shake motorcycle structure, to test the availability of descriptor state-space system to identify real structures.
Subjects
system identification
descriptor systems
Kronecker canonical form
MOESP space algorithm
Type
thesis
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