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Conference Papers-Robust Control
Note: The papers on this website may differ from the published versions, both in format and in content.
Robust Control:
A. Jadbabaie, C.T. Abdallah,
and P. Dorato,
"Guaranteed-Cost Control of Polynomial Nonlinear Systems",
Proceedings of the 37th IEEE Conference on Decision and Control, pp.4100-4102, Tampa, FL., Dec. 1998.
[pdf]
Abstract: This paper deals with the control of a class of nonlinear systems which are affine
in the control. We use Bernstein polynomials and Polytopic Linear Differential Inclusion (PLDI) to design gain-scheduled
controllers using a guaranteed cost framework.
V. koltchinski, S. Efromovich,
C.T. Abdallah, G.L. Heileman
"Tracking Control of Uncertain Systems",
Proceedings of the 37th IEEE Conference on Decision and Control, pp.1867-1868, Tampa, FL., Dec. 1998.
[pdf]
Abstract: This paper deals with the problem of designing output tracking controllers for uncertain systems. The systems
we consider may be non-minimum phase but are restricted to be linear. The problem is motivated by control applications where a desired output trajectory
is specied, and the corresponding input to the system is to be found.
F. L. Lewis, G. Maliotis, C. T. Abdallah,
"Robust Adaptive Control for a Class of Partially Known Nonlinear Systems", Proceedings of the 27th Conference
on Decision and Control, pp. 24-30, Austin, TX, Dec. 1988.
[pdf]
Abstract: An adaptive controller is developped that takes advantage of the structure and any
known dynamics of the system in order to increase speed of adaptation and relax the conditions required for convergence.
The control design method has two stages. First, the known dynamics are separated out and used to perform a global
linearization on the nonlinear system. Second, a model-reference adaptive control, based on the lyapunov stability
criterion, is designed for the remaining unknown portion of the plant. This control scheme is shown to relax several
assumptions usually made in applying adaptive control to a manipulator system. For instance, it relaxes the common
assumption that the time varying plant is close to the desired model.
A. Jadbabaie, C.T. Abdallah,
M. Jamshidi, and P. Dorato,
"Guaranteed-Cost Control of the Nonlinear Benchmark Problem Using Model-Based Fuzzy Systems",
Proceedings of 1998 IEEE International Conference on Control Application, pp.792-796, Trieste , Italy, 1-4 Sept. 1998.
[pdf]
Abstract: In this paper we design a state-feedback controller for the nonlinear benchamrk problem.
Our approach relies on the use of Takagi-Sugeno fuzzy models to approxiamte the nonlinear system. Once the fuzy model is
obtained, we develop a guaranteed-cost framework to design the controller using Linear Matrix Inequality methods and recently
obtained relaxed stability conditions. We show that our proposed controller will not only stabilize the system, but also
has satisfactory disturbance attenuation properties.
A. Jadbabaie, C.T. Abdallah,
D. Famularo, P. Dorato,
"Robust, Non-Fragile and Optimal Controller Design Via Linear Matrix Inequalities",
Proceedings of the American Control Conference, pp.2842-2846, Philadelphia, PN, June 1998.
[pdf]
Abstract: In this article, we introduce a robust non-fragile state feedback controller
which is also optimal with respect to a quadratic performance index, using Linear Matrix Inequalities (LMIs). The
uncertainties are assumed to be polytopic, both in the controller gains and the system dynamics. A numerical example
is presented to demonstrate the efficiency of this method, and the controller turns out to be robust with respect to the uncertainties
in the plant and the controller.
D. Famularo, C.T. Abdallah,
A. Jadbabaie, P. Dorato
W.M. Haddad,
"Robust Non-fragile LQ Controllers: The Static State Feedback Case",
Proceedings of the American Control Conference, pp.1109-1113, Philadelphia, PN, June 1998.
[pdf]
Abstract: This paper describes the synthesis of non-fragile or resilient regulators for linear systems. The general framework
for fragility is described using state-space methodologies, and the LQ/Xz static state-feedback case is examined
in detail. We discuss the multiplicative structured uncertainties case, and propose remedies of the fragility
problem using a convex programming framework (LMIs) as a possible solution scheme. The benchmark problem
is taken as an example to show how controller gain variations can affect the performance of the closed-loop system.
R.A. Luke,
P. Dorato, C.T. Abdallah,
"Guaranteed Gain-Phase Margins for Multi-Model Control",
Proceedings of the American Control Conference, pp.3497-3501, Philadelphia, PN, June 1998.
[pdf]
Abstract: In the simultaneous performance design problem considered by the authors [5], linear-quadratic cost function
state and control weightings are assumed. A single static state feedback gain is determined which minimizes
the guaranteed-cost bound [1] for each of the systems. It is now shown that subject to certain restrictions,
the guaranteed-cost gain results in “non-fragile” system control: an infinite increasing gain margin, a decreasing
gain margin of 1/2, and phase margins of sixty degrees for each system. The converse is also considered: given
a guaranteed-cost gain, the set of all state and control weightings are found for which that gain remains optimal.
This is possible through the use of a Kalman matrix identity.
P. Dorato, C. T. Abdallah and D. Famularo,
"On the Design of Non-Fragile Compensators via Symbolic Quantifier Elimination",
World Automation Congress(WAC'98), Alaska, May 10-14, 1998. Proceedings
printed in Intelligent Automation and Control, Volume 6, TSI Press, pp. 363-368, Albuquerque, NM.
[pdf] [ps]
Abstract: In this paper symbolic quantifier elimination methods are used to explore the fragility of
feedback compensators, and to design feedback systems with non-fragile compensators. A compensator is said to be fragile
if given variations in compensator parameters result in significant deterioration of feedback performance.
The issue of fragility is important in understanding the level of acurracy required to implement a given
compensator design.
V. Koltchinski, S. Efromovich, C. T. Abdallah and G.L. Heileman,
"Tracking Control of Uncertain Systems",
Proceedings IEEE Conference on Decision and Control, pp.1867-1868, 1998.
[pdf] [ps]
Abstract: This paper deals with the problem of designing output
tracking controllers for uncertain systems. The systems we consider may be non-minimum phase but are
restricted to be linear. The problem is motivated by control applications where a desired output trajectory
is specified, and the corresponding input to the system is to be found.
C. T. Abdallah and F.Perez-Gonzalez,
"On the Fragility of High-Dimensional Controllers",
Proceedings IEEE Conference on Decision and Control, 1998.
[pdf] [ps]
Abstract:In this paper we study the fragility of controllers designed to optimize some performance
indices. We trace the fragility problem to the dimension of the resulting controllers, and use
results from high-dimensional geometry to analyze the problem both in the continuous and
discrete domains...
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