Actively Tuned Non-Collocated Suppression: 
Unexplored Venue in Vibration Science, a Paradox and a Benchmark Problem

Prof. Nejat Olgac, Mechanical Engineering Department,

University of Connecticut, USA, http://www.engr.uconn.edu/alarm/

Τετάρτη 15 Μαΐου 2019, 13:00-14:15

Αίθουσα Συνεδριάσεων

2ος όροφος Πολυωρόφου Κτιρίου Τμήματος Μηχανολόγων & Αεροναυπηγών Μηχανικών

ΠΕΡΙΛΗΨΗ
We revisit a broadly studied actively-tuned vibration absorbers in this presentation from several unconventional angles.  First, the absorber is conceived to exact suppression at a designated location in the structure other than its point of attachment (thus non-collocated suppression).  This objective sets a virgin domain which has been very poorly explored to date.  Second, the absorber is tunable to suppress all residual oscillations at that point against a harmonic excitation, overriding all modes intrinsic to the system. Furthermore the tuning is achieved in real time, using collocated control logic (which is not unique) with a feedback gain and delay.  This novel combination of vibration absorption characteristics is achieved using the well-studied Delayed Resonator (DR) concept.  Asymptotic stability of the ensuing dynamics is examined in the parametric space and operable frequency limitations are declared.  We will provide an overarching theorem for the design of such a non-collocated absorber. A paradoxical relationship will be reviewed which arises between the steady-state energy levels of passive and actively-tuned absorber deployments.  This phenomenon leads us to an intriguing benchmark problem.  All of these contributions are elucidated through example case studies.

Prof. Nejat Olgac, Dr. Eng. Sci. Columbia Univ. 1976, M.Sc. Technical Univ. of Istanbul, Turkey 1972 (summa-cum-laude), both in Mechanical Engineering.  He was engaged in manufacturing industry in Istanbul (1976-81).  Since 1981 he has been a Professor with the Mechanical Engineering Department of the University of Connecticut.  His research interests are in robust nonlinear controls, active vibration absorption, time-delayed systems, micromanipulation in bio-engineering. Dr. Olgac holds four patents, three on the Delayed Resonator active vibration suppression technique (1995-1996-1999) and a fourth one on anti-chatter concepts in simultaneous machining (2011). He is the director of Advanced Laboratory for Robotics, Automation and Manufacturing (ALARM) at UConn. Dr. Olgac was Visiting Professor at INRIA (Sophia-Antipolis, France) 1988-89, SEW Eurodrive Fellow – Guest Professor at Technical Univ. of Munich, Germany in 1995-96 and Visiting Professor at Harvard University 2002-03). He served on the editorial board of the ASME Trans. of Dynamic Systems, Measurement and Control (1996-2004), and the guest editor of the Special Issue of JDSMC on Time Delayed Systems (June, 2003), is presently on the Editorial Boards of  IEEE, Tran. Control System Technology, J. Vibration and Control, Int. J. of Mechatronics and Manufacturing Systems. He also served a member and later as the Chairman of the Executive Committee of the ASME Dynamic Systems and Control Division (2001-6). He was the General Chair of IFAC Time Delay Systems Workshop (TDS) 2012, and General Chairman of ASME Dynamic Systems and Controls Conference, DSCC 2013.  He is a member of the ASME Systems and Design Group Operating Board, he also sits on the A2C2 (American Automatic Control Council) Board of Directors. He is the recipient of a UCONN Research Excellence Award (2015) and ASME Distinguished Engineer of the Year, Hartford Chapter, CT (2015).  Prof. Olgac is a member of the Connecticut Academy of Science and Engineering (CASE), Fellow of ASME and Senior Member of IEEE. He was selected as the recipient of Doctor Honoris Causa (https://www.cvut.cz/en/doctor-honoris-causa-ctu-in-prague) from the Czech Tech.University, Prague (2019).