U OF M COLLEGE OF ENGINEERING
CONTROL SEMINAR SERIES
WINTER TERM 1998
Dr. Mrdjan Jankovic
Scientific Research Labs
Ford Motor Company
Friday, February 6, 1998
4:00 - 5:00 pm
Title: Robust Nonlinear Controller Design: Application to Diesel Engines
A method of designing robust controllers
for nonlinear systems is presented and applied to a
simplified model of a diesel engine equipped with a variable
geometry turbocharger (VGT)
and an exhaust gas recirculation (EGR) valve.
VGT varies the turbine flow area as a function of the engine
operating condition thus providing improved fuel economy and
faster torque response. EGR valve allows controlled recirculation
of the exhaust gas into the intake manifold to reduce
NOx emissions. However,
simultaneous operation of the two actuators results in
significant interactions. The control design problem is additionally
complicated by inherently nonlinear nature of the diesel
engine. As a result, two decoupled PID regulators
have not been able to deliver satisfactory performance.
Instead, the author proposes
a recently developed robust control design method which applies
to multi-input nonlinear systems
with a known control Lyapunov function (CLF).
The robustness guaranteed by the design is the nonlinear
equivalent of the robustness of linear
optimal regulators: the well known (1/2,infinity)
gain margin and +/- 60° phase margin. This robustness
to unmodeled dynamics allows simplification in the diesel
engine model used for controller design.
For one such model a CLF is
constructed using the tools of geometric control theory.
The resulting robust CLF based controller takes a very simple form.
The talk will address the issues related to the controller design.
Performance will be illustrated by simulations on a detailed model
of a diesel engine.
Mrdjan Jankovic received the B.S. degree from the University of Belgrade,
Yugoslavia, in l986 and the M.S. and D.Sc. degrees from Washington University,
St. Louis, in l989 and l992. He held research positions with the University
of Belgrade, l986-87, Washington University, l992-94, and the University
of California, Santa Barbara, l994-95. In November l995, he joined Ford
Scientific Research Laboratories, where he is currently working on the development
of advanced powertrain control systems.
Dr. Jankovic's research interests include nonlinear estimation,
nonlinear and adaptive control with application to powertrain control systems
He currently serves as an Associate Editor for IEEE
Transactions on Control Systems Technology.
With R. Sepulchre and P. V. Kokotovic he has co-authored the book
"Constructive Nonlinear Control", Springer-Verlag, London, l997.
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