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Hassan K. Khalil

Bio: Hassan K. Khalil is an academic researcher from Michigan State University. The author has contributed to research in topics: Nonlinear system & Nonlinear control. The author has an hindex of 57, co-authored 284 publications receiving 15992 citations. Previous affiliations of Hassan K. Khalil include Ford Motor Company & National Chiao Tung University.


Papers
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Proceedings ArticleDOI
09 Jul 2007
TL;DR: A new adaptive control approach is proposed for a class of systems represented by an unknown hysteresis nonlinearity preceding unknown linear dynamics, which shows promise in simulation of output tracking for a piezoelectric positioner.
Abstract: In this paper a new adaptive control approach is proposed for a class of systems represented by an unknown hysteresis nonlinearity preceding unknown linear dynamics. The existing adaptive inverse control framework relies on over-parametrization to handle the bilinearly coupled parameters of hysteresis and dynamics, which often results in prohibitively many parameters if faithful hysteresis models are adopted. The proposed scheme eliminates over-parameterization by adapting the hysteresis parameters and the dynamics-related controller parameters at different time scales, both much slower than the plant dynamics. The scheme shows promise in simulation of output tracking for a piezoelectric positioner, where the hysteresis nonlinearity is modeled by a Preisach operator. As a first step towards full analysis of the closed-loop system, an identification problem containing bilinear parameterization is analyzed. It is shown that multi-time-scale, slow adaptation leads to local, asymptotic parameter convergence under appropriate conditions.

27 citations

Journal ArticleDOI
TL;DR: An impulsive control method is proposed for enlarging the region of attraction of stabilized equilibria of underactuated systems by obtaining an estimate of the area of attraction and intersection of this region with the impulse manifold.
Abstract: Underactuated dynamic systems typically have multiple isolated equilibria, and therefore, a stabilizing controller is effective only in the region of attraction of the equilibrium. An impulsive control method is proposed for enlarging the region of attraction of stabilized equilibria of underactuated systems. The method relies on obtaining an estimate of the region of attraction and intersection of this region with the impulse manifold. The efficacy of the method is demonstrated through simulations and experiments.

27 citations

Journal ArticleDOI
TL;DR: A high-gain predictor for output feedback control of nonlinear systems in the presence of input, output, and state delays is designed and positively invariant sets are found to verify boundedness, exponential stability, and performance recovery.

27 citations

Proceedings ArticleDOI
01 Jan 2004
TL;DR: In this paper, the authors consider field-oriented speed control of induction motors without rotor position sensors and derive a 6th-order nonlinear model that describes the motor in field oriented coordinates.
Abstract: We consider field-oriented speed control of induction motors without rotor position sensors. We augment the traditional approach with flux and speed observers and derive a sixth-order nonlinear model that describes the motor in field-oriented coordinates. The model takes into consideration the error in flux estimation. The flux regulation problem is a simple one and we follow the traditional approach of using PI controllers. For the speed regulation problem, we simplify the model by assuming that flux regulation takes place relatively fast and by using a (high-gain) PI controller to regulate the q-axis current to its command. This results in a third-order nonlinear model in which the speed and two flux estimation errors are the state variables, the q-axis current is the control input and a speed estimate (provided by the high-gain observer) is the measured output. This nonlinear model is the main contribution of this paper because it enables us to perform rigorous analysis of the closed-loop system under different controllers. In the current paper, we limit our analysis to the design of PI controllers via linearization. The linearized model is used to study when a PI controller can stabilize the nonlinear third-order model at the desired equilibrium point. The analysis reveals an important role played by the steady-state product of the flux frequency and the q-axis current in determining the control properties of the system.

25 citations

Journal ArticleDOI
TL;DR: If the actuator dynamics are sufficiently fast, the output feedback controller will stabilize the origin of the actual system, and it is shown that the actuATOR dynamics need not be faster than the observer dynamics.

25 citations


Cited by
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Journal ArticleDOI

[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Book
01 Jan 1994
TL;DR: In this paper, the authors present a brief history of LMIs in control theory and discuss some of the standard problems involved in LMIs, such as linear matrix inequalities, linear differential inequalities, and matrix problems with analytic solutions.
Abstract: Preface 1. Introduction Overview A Brief History of LMIs in Control Theory Notes on the Style of the Book Origin of the Book 2. Some Standard Problems Involving LMIs. Linear Matrix Inequalities Some Standard Problems Ellipsoid Algorithm Interior-Point Methods Strict and Nonstrict LMIs Miscellaneous Results on Matrix Inequalities Some LMI Problems with Analytic Solutions 3. Some Matrix Problems. Minimizing Condition Number by Scaling Minimizing Condition Number of a Positive-Definite Matrix Minimizing Norm by Scaling Rescaling a Matrix Positive-Definite Matrix Completion Problems Quadratic Approximation of a Polytopic Norm Ellipsoidal Approximation 4. Linear Differential Inclusions. Differential Inclusions Some Specific LDIs Nonlinear System Analysis via LDIs 5. Analysis of LDIs: State Properties. Quadratic Stability Invariant Ellipsoids 6. Analysis of LDIs: Input/Output Properties. Input-to-State Properties State-to-Output Properties Input-to-Output Properties 7. State-Feedback Synthesis for LDIs. Static State-Feedback Controllers State Properties Input-to-State Properties State-to-Output Properties Input-to-Output Properties Observer-Based Controllers for Nonlinear Systems 8. Lure and Multiplier Methods. Analysis of Lure Systems Integral Quadratic Constraints Multipliers for Systems with Unknown Parameters 9. Systems with Multiplicative Noise. Analysis of Systems with Multiplicative Noise State-Feedback Synthesis 10. Miscellaneous Problems. Optimization over an Affine Family of Linear Systems Analysis of Systems with LTI Perturbations Positive Orthant Stabilizability Linear Systems with Delays Interpolation Problems The Inverse Problem of Optimal Control System Realization Problems Multi-Criterion LQG Nonconvex Multi-Criterion Quadratic Problems Notation List of Acronyms Bibliography Index.

11,085 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a state-of-the-art survey of ANN applications in forecasting and provide a synthesis of published research in this area, insights on ANN modeling issues, and future research directions.

3,680 citations

Journal ArticleDOI
Arie Levant1
TL;DR: In this article, the authors proposed arbitrary-order robust exact differentiators with finite-time convergence, which can be used to keep accurate a given constraint and feature theoretically-infinite-frequency switching.
Abstract: Being a motion on a discontinuity set of a dynamic system, sliding mode is used to keep accurately a given constraint and features theoretically-infinite-frequency switching. Standard sliding modes provide for finite-time convergence, precise keeping of the constraint and robustness with respect to internal and external disturbances. Yet the relative degree of the constraint has to be 1 and a dangerous chattering effect is possible. Higher-order sliding modes preserve or generalize the main properties of the standard sliding mode and remove the above restrictions. r-Sliding mode realization provides for up to the rth order of sliding precision with respect to the sampling interval compared with the first order of the standard sliding mode. Such controllers require higher-order real-time derivatives of the outputs to be available. The lacking information is achieved by means of proposed arbitrary-order robust exact differentiators with finite-time convergence. These differentiators feature optimal asymptot...

2,954 citations