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Karutz P.,ETH Zurich | Nussbaumer T.,Levitronix GmbH | Gruber W.,Austrian Center of Competence in Mechatronics | Kolar J.W.,ETH Zurich
IEEE Transactions on Industrial Electronics

This paper presents an optimization-procedure yielding for minimal acceleration times for different speed ranges using the example of a magnetically levitated slice motor with a large air gap. The optimization is based on a set of analytical equations together with selected 3-D finite element method simulations with the aim to optimize both the stator geometry and the number of drive turns. It is shown that the use of 3-D instead of 2-D simulation tools is obligatory for motors with large air gaps for achieving sufficient simulation accuracy. The relevant equations for the optimization are derived, and the accuracy of the proposed method is verified by measurements on a prototype system. Copyright © 2010 IEEE. Source

Sherif K.,Austrian Center of Competence in Mechatronics | Sherif K.,Johannes Kepler University | Witteveen W.,Upper Austria University of Applied Sciences | Mayrhofer K.,Siemens AG
Acta Mechanica

A number of sets of modes, for example eigenmodes, constraint modes, inertia-relief attachment modes, may be used to describe the linear elastic deformation of a flexible body in multibody dynamics. It is always possible to transform modes so that the conditions of the Buckens-frame are fulfilled. The latter frame leads to serious simplifications in the equations of motion, but cannot avoid a coupling between the body's rotational rigid body motion and its elastic deformation. In the present paper the deformation modes will be subdivided into low- and high-frequency modes. It will be shown that the latter-mentioned coupling effect of the second ones can be safely neglected in comparison with the first ones. Consequently, the high-frequency components can be removed from time integration at all, which leads to significant savings of computational effort while the accuracy regarding the body's deformation remains almost the same. In the case of a known frequency content of external excitation, an algorithm is given so that the available modes can be automatically separated into such low- and high-frequency modes. While the number of low-frequency modes remains more or less constant, there is a significant trend to use an increased number of high-frequency modes. Examples are moving loads (e.g.; guidance) or distributed loads as they occur in contact problems or when fluid pressure is acting on surfaces. A final numerical example is given in order to demonstrate the potential of the proposed method. © 2012 Springer-Verlag. Source

Wagner T.,Christian Doppler Laboratory | Schuster S.,Johannes Kepler University | Pfeil R.,Austrian Center of Competence in Mechatronics | Stelzer A.,Christian Doppler Laboratory
IEEE Transactions on Instrumentation and Measurement

Sinusoidal frequency estimation based on discrete Fourier transform provides accurate results for well-separated spectral tones. However, if a single sinusoid is disturbed by other tones, estimation accuracy may suffer significantly. In particular, the bias can increase considerably when the frequencies of the disturbances are close to that of the desired sinusoid. In addition to frequency estimation by maximization of the Schuster periodogram, examining a frequency located on the opposite side of the disturbance at the edge of the cost function may reduce its influence on the bias of the estimator. In this paper, we present an empirical appraisal of this bias reduction. Since our edge estimation procedure increases the variance of the estimated frequency, we also present an analytical method for assessing this increase. Possible applications are measurement or tracking tasks where frequency estimates with low bias are essential to the working of an overall measurement system. Further, we describe a method that combines the advantages of peak and edge estimation. All results were validated using simulations and data obtained from a frequency-modulated continuous-wave radar system. © 1963-2012 IEEE. Source

Gerstmayr J.,Austrian Center of Competence in Mechatronics | Sugiyama H.,University of Iowa | Mikkola A.,Lappeenranta University of Technology
Journal of Computational and Nonlinear Dynamics

The aim of this study is to provide a comprehensive review of the finite element absolute nodal coordinate formulation, which can be used to obtain efficient solutions to large deformation problems of constrained multibody systems. In particular, important features of different types of beam and plate elements that have been proposed since 1996 are reviewed. These elements are categorized by parameterization of the elements (i.e., fully parameterized and gradient deficient elements), strain measures used, and remedies for locking effects. Material nonlinearities and the integration of the absolute nodal coordinate formulation to general multibody dynamics computer algorithms are addressed with particular emphasis on visco-elasticity, elasto-plasticity, and joint constraint formulations. Furthermore, it is shown that the absolute nodal coordinate formulation has been applied to a wide variety of challenging nonlinear dynamics problems that include belt drives, rotor blades, elastic cables, leaf springs, and tires. Unresolved issues and future perspectives of the study of the absolute nodal coordinate formulation are also addressed in this investigation. Copyright © 2013 by ASME. Source

Hehenberger P.,Johannes Kepler University | Poltschak F.,Johannes Kepler University | Zeman K.,Johannes Kepler University | Amrhein W.,Johannes Kepler University | Amrhein W.,Austrian Center of Competence in Mechatronics

This paper presents an approach for using hierarchical models in the design of mechatronic systems. The utilization and proper combination of solution principles from different domains of mechatronics allow an extended variety and quality of principal solutions, where hierarchical models serve as very important tools for complex design tasks. In order to master the mechatronic design approach and to benefit from it as much as possible, a hierarchical design process is proposed, in which the domain-specific design tasks need not be integrated as a whole on the mechatronic level of the design task. Consequently the models should cover the different views on a system as well as the different degrees of detailing which leads from a hierarchy of models to a hierarchy of design parameters. The specific views of the object represent the relevant phenomena/effects of interest such as geometry, dynamics, stability or material and are used as interfaces for the design engineer during her/his work. Their description by significant quantities is used for analyzing different mechatronic design concepts. The approach is demonstrated by studying the activities during the design process of synchronous machines. © 2010 Elsevier Ltd. All rights reserved. Source

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