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Proceedings Paper

Analog and digital feedback for magnetostrictive transducer linearization
Author(s): Rick L. Zrostlik; David L. Hall; Alison B. Flatau
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Paper Abstract

Terfenol-D is a `giant' magnetostrictive material offering mechanical strains on the order of 1000 X 10-6 m/m. Dynamic transducers constructed using Terfenol-D as the motion source offer displacements based on approximately +/- 500 (mu) strain. These transducers are known to be nonlinear; however, in some applications they can be treated as linear systems and their behavior approximated by the classic pair of linear transduction equations. This approximation is made in this study to facilitate analysis. Several simple analog and digital controllers are used with acceleration feedback to improve transducer linearity. A nonlinearity of particular importance when using Terfenol-D transducers is wave form distortion. The distortion is a result of nonlinear strains vs. magnetization relationships and the magnetic hysteresis occurring within the Terfenol-D. The net result is the presence of integer harmonics in the transducer voltage, current, and output velocity. Assuming the harmonics to be disturbances, an expression is developed for predicting the change in harmonic amplitudes of acceleration as a function of frequency and parameters for the controller, load, and transducer. Experimental measurements comparing controlled and uncontrolled output accelerations are presented to validate the approach. A significant extension of the linear range of transducer behavior, due to feedback control, is also demonstrated.

Paper Details

Date Published: 31 May 1996
PDF: 10 pages
Proc. SPIE 2715, Smart Structures and Materials 1996: Mathematics and Control in Smart Structures, (31 May 1996); doi: 10.1117/12.240832
Show Author Affiliations
Rick L. Zrostlik, Iowa State Univ. (United States)
David L. Hall, Iowa State Univ. (United States)
Alison B. Flatau, Iowa State Univ. (United States)

Published in SPIE Proceedings Vol. 2715:
Smart Structures and Materials 1996: Mathematics and Control in Smart Structures
Vasundara V. Varadan; Jagdish Chandra, Editor(s)

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