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Identification of a second-order mechanical system model from a state space realizationMany system identification algorithms produce models in modern state variable form. When a mechanical system is identified one knows that there must be a model in second order form. In structural dynamics one is interested in either a modal model of the system, or in a model including a mass matrix, stiffness matrix and a damping matrix. In this paper, algorithms are developed that convert a modern state space realization into the above two representations of interest in mechanical systems. The algorithm can be used with any identification methods that produce a modern state variable representation such as the Eigensystem Realization Algorithm (ERA), its modified version by data correlation (ERA/DC), and combinations of these with Observer/Kalman Filter Identification (OKID). An algorithm is developed that allows one to identify the damping matrix in a model representation, so that one determines how near to modal the damping is in the system, and can therefore understand the degree to which the modes are coupled by the damping in the system. A second algorithm produced the mass, damping, and stiffness matrices, given the input and output matrices. It is assumed that the number of sensors (or the number of actuators) is greater than or equal to the number of modes in the system, and it is proved that this is a necessary condition to be able to uniquely identify these matrices. Experience with examples suggests that a singular value truncation involved in these algorithms can help one determine the true system order. This truncation has the benefit of knowledge of the correct form for a mechanical system model, which is not present in the modern control identification algorithm.
Document ID
19950049766
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Tseng, Dong-Huei
(Columbia Univ. New York, NY, US, United States)
Longman, Richard W.
(Columbia Univ. New York, NY, US, United States)
Juang, Jer-Nan
(NASA Langley Research Center Hampton, VA, US, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1993
Publication Information
Publication: In: Spaceflight mechanics, 1993; AAS(AIAA Spaceflight Mechanics Meeting, 3rd, Pasadena, CA, Feb. 22-24, 1993, Parts 1 & 2 . A95-81344
Publisher: American Astronautical Society (Advances in the Astronautical Sciences, Vol. 82, Pts. 1 & 2)
ISSN: 0065-3438
Subject Category
Mechanical Engineering
Accession Number
95A81365
Funding Number(s)
CONTRACT_GRANT: NAG1-649
Distribution Limits
Public
Copyright
Other

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