Einladung zum Vortrag im Kolloquium Technische Kybernetik

The inerter concept and device: application to vehicle suspension

Prof. Malcolm C. Smith
Department of Engineering
University of Cambridge, Cambridge, U.K.

    Zeit: Donnerstag · 13. 01. 2005 · 16:00 Uhr
    Ort: Raum 3.241 · Pfaffenwaldring 9 · Campus Stuttgart-Vaihingen

Abstract

The force-current and force-voltage analogies between mechanical and electrical networks are basic and very well-known. What is also well-known, but not always emphasised, is that the mass element fails to be a true network dual of the spring. This is due simply to the fact that Newton’s Second Law relates the acceleration of the mass to a fixed point in an inertial frame, which in network terms means that one “terminal” of the mass is grounded. Such a restriction does not apply to the spring or damper, or to any of the three basic electrical elements. This fact has important consequences for network synthesis. Standard realization procedures of passive electrical circuit theory show that any passive electrical impedance is positive real, and that any positive real rational function may be realised as the driving-point impedance of a network comprising resistors, capacitors and inductors only. There is a clear problem in translating this result over to mechanical networks if a given realisation contains a capacitor which has neither terminal connected to ground. A further drawback arises with the use of the mass element as the dual of the spring for the purpose of synthesis. Namely, it may be important to assume that the mechanical device associated with the “black-box impedance” to be designed has negligible mass compared to other masses in the system. Clearly this is unreasonable if (possibly) large masses may be required for its realisation. The purpose of this talk is to describe a new mechanical circuit element called the “inerter”, which is capable of simple physical realisation, to overcome these difficulties. Possible applications of the inerter in linear vibrations and vehicle suspensions will be discussed.

Biographical Information

Malcolm Smith was educated at the University of Cambridge, England where he received the B.A. degree in mathematics in 1978, the M.Phil degree in control engineering and operational research in 1979, and the Ph.D. degree in control engineering in 1982. He was subsequently a Research Fellow at the German Aerospace Center, DLR, Oberpfaffenhofen, Germany, a Visiting Assistant Professor and Research Fellow with the Department of Electrical Engineering at McGill University, Montreal, Canada, and an Assistant Professor with the Department of Electrical Engineering at the Ohio State University, Columbus, USA. In 1990 he returned to Cambridge as a Lecturer in the Department of Engineering and became a Reader in 1997 and Professor in 2002. He is a Fellow of Gonville and Caius College. Dr Smith's research interests include Control System Design, Frequency Response Methods, H-infinity Optimization, Nonlinear Systems, Active Suspension and Mechanical Systems. He was a co-recipient of the George Axelby Outstanding Paper Award in the IEEE Automatic Control Transactions for the years 1992 and 1999, both times for joint work with Dr Tryphon T. Georgiou.