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From Stability to Performance-Driven Control Configurations for Multi Delay Systems

Most dead-time compensation (DTC) schemes developed to-date can be regarded as stability driven since their predictive elements are conventionally structured to eliminate delays from the closed-loop characteristic equation. In the single-delay case this approach happens to also agree well with a number of optimization-based design methods. This, however, is no longer true in the multiple-delay case, where stability driven DTCs might yield poor closed-loop performance. In fact, there appears to be no clear choice of the DTC configuration and conventional wisdom even suggests that in certain situations it may be advantageous to add artificial loop delays to control channels with shorter delays to equalize input dead times. This talk aims at convincing you that the DTC structure should be performance driven. To simplify the exposition, systems with multiple input delays will be considered and used to show how performance analysis can lead to a novel DTC configuration termed FASP (feedforward action Smith predictor). Alongside the conventional internal feedback, this configuration contains novel interchannel feedforward controllers and never adds artificial loop delays. The structure of FASP has an intuitive explanation and effectively prompts a paradigm shift in DTC for systems with multiple loop delays. Experimental results of the application of the FASP to an upgraded version of the quadruple tank process with multiple delays laboratory set-up confirm the potential superiority of the FASP over existing state of the art dead-time compensators.

Type of Seminar:
IfA Seminar
Prof. Zalman Palmor
Technion - Israel Institute of Technology, Haifa, Israel
Jun 09, 2011   14:15

ETZ E6, Gloriastrasse 35
Contact Person:

Manfred Morari
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Biographical Sketch:
Zalman J. Palmor is the Joseph and Sadie Danciger Professor of Engineering and the Deputy Executive Vice President for Academic Affairs at the Technion – Israel Institute of Technology. He received his BSc and MSc degrees in Mechanical Engineering from the Technion and his PhD in Chemical Engineering from the City College, CUNY, New York, in 1976. He worked for Taylor Instrument Co., Rochester NY, for a few years before joining the Faculty of Mechanical Engineering at the Technion IIT in 1979, where he is a full professor. He was the Dean of the Faculty for five years until December 2006. Zalman Palmor has been actively involved with industry and international engineering entities as a consultant, and some of his control algorithms were installed and distributed world-wide by leading vendors of process control equipment. Zalman Palmor has been a guest at IfA since March and will be leaving in a few weeks.