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Showing papers by "Hassan K. Khalil published in 1999"


Journal ArticleDOI
TL;DR: It is shown that the performance of a globally bounded partial state feedback control of an input-output linearizable system can be recovered by a sufficiently fast high-gain observer.
Abstract: It is shown that the performance of a globally bounded partial state feedback control of a certain class of nonlinear systems can be recovered by a sufficiently fast high-gain observer. The performance recovery includes recovery of asymptotic stability of the origin, the region of attraction, and trajectories.

655 citations


Journal ArticleDOI
TL;DR: This paper studies discrete-time implementation of high-gain observers and their use as numerical differentiators, in noise-free as well as noisy measurements, and shows that discretization using the bilinear transformation method gives better results than otherDiscretization methods.
Abstract: High-gain observers have been used in non-linear control to estimate derivatives of the output. In this paper, we study discrete-time implementation of high-gain observers and their use as numerical differentiators, in noise-free as well as noisy measurements. We show that discretization using the bilinear transformation method gives better results than other discretization methods. We also show that many of the available numerical differentiators are special cases of the bilinear discrete-time equivalents of full-order or reduced-order high-gain observers.

160 citations


Journal Article
TL;DR: In this article, a brief introduction to high-gain observers in nonlinear feedback control is given, with emphasis on the peaking phenomenon and the role of control saturation in dealing with it.
Abstract: The theory of high-gain observers has been developed for about twenty years. This paper is a brief introduction to high-gain observers in nonlinear feedback control, with emphasis on the peaking phenomenon and the role of control saturation in dealing with it. The paper surveys recent results on the nonlinear separation principle, conditional servo compensators, extended high-gain observers, performance in the presence of measurement noise, sampled-data control, and experimental testbeds.

81 citations


Proceedings ArticleDOI
02 Jun 1999
TL;DR: In this article, an adaptive output feedback control scheme is presented for output tracking of a class of continuous-time nonlinear plants, where an RBF neural network is used to adaptively compensate for the plant nonlinearities.
Abstract: An adaptive output feedback control scheme is presented for output tracking of a class of continuous-time nonlinear plants. An RBF neural network is used to adaptively compensate for the plant nonlinearities. The network weights are adapted using a Lyapunov-based design. The method uses parameter projection, control saturation, and a high-gain observer to achieve semi-global uniform ultimate boundedness. The efficacy of the proposed method is demonstrated through simulations. The simulations also show that by using adaptive control in conjunction with robust control, it is possible to tolerate larger approximation errors resulting from the use of lower-order networks.

40 citations


Proceedings ArticleDOI
01 Jan 1999
TL;DR: In this article, a nonlinear model is used to represent the vehicle dynamics of each vehicle within the platoon, and the computer in the vehicle processes the measured data and generates proper throttling and braking actions to follow the vehicle in front at a safe distance.
Abstract: A technique for the longitudinal control of a platoon of automated vehicles is presented. A nonlinear model is used to represent the vehicle dynamics of each vehicle within the platoon. The controlled vehicle is assumed to be capable of measuring (or estimating) necessary dynamical information from the vehicle immediately in front of it by its on-board sensors. The computer in the vehicle processes the measured data and generates proper throttling and braking actions to follow the vehicle in front at a safe distance. Simulations are presented for the case of a platoon of four cars following a leader.

16 citations


Proceedings ArticleDOI
02 Jun 1999
TL;DR: A nonlinear robust adaptive output feedback speed controller for induction motors that guarantees that the speed tracking error can be made small by choice of certain design parameters.
Abstract: A nonlinear robust adaptive output feedback speed controller is designed for induction motors. The control uses only measurements of the rotor position and stator current and temperature. It contains two observers, a ninth-order adaptive observer to estimate the rotor flux and rotor resistance, and a third-order high-gain observer to estimate the rotor speed and acceleration from its position. The control is robust to uncertainties in the motor parameters and a bounded time-varying load torque. It guarantees that the speed tracking error can be made small by choice of certain design parameters. Experimental results are shown.

10 citations


Proceedings ArticleDOI
07 Dec 1999
TL;DR: Simulation is used to compare the performance of different output feedback nonlinear adaptive controllers using the high-gain observer method and the H/sup /spl infin// method.
Abstract: A number of techniques have been developed in the past for adaptive control of nonlinear systems using output feedback. These techniques have been compared from a number of viewpoints like the underlying class of nonlinear systems, the nature of the theoretical results (e.g., global versus semiglobal), and the issue of over-parameterization. One issue that has not received enough attention is how these different techniques compare when they can be applied to the same system. For example, the class of nonlinear systems in output feedback form, treated in the books by Krstic et al. (1995) and Marino and Tomei (1995), can also be treated by the high-gain observer method of Khalil (1996, 1997) and the H/sup /spl infin// method of Tezcan and Basar (1999). We use simulation to compare the performance of different output feedback nonlinear adaptive controllers.

8 citations


Book ChapterDOI
01 Jan 1999

5 citations


Book ChapterDOI
01 Jan 1999

2 citations


Book ChapterDOI
01 Jan 1999

1 citations


Reference EntryDOI
27 Dec 1999
TL;DR: In this paper, the authors presented the time-scale properties of the standard model of large power systems and applied these properties to large power system applications, including large-scale power systems.
Abstract: The sections in this article are 1 Time-Scale Properties of the Standard Model 2 Examples 3 Stability Analysis 4 Composite Feedback Control 5 Applications to Large Power Systems 6 Further Reading Keywords: two-time-scale systems; model order reduction; slow manifold; boundary layer; relaxation oscillation; multiple time scales; singular perturbation; stability properties under perturbations

Proceedings ArticleDOI
07 Dec 1999
TL;DR: A two-semester senior level course sequence is being developed and integrated into the electrical engineering and mechanical engineering curricula as mentioned in this paper, which is offered as a technical elective in the Fall semester, while the second course is offered in the Spring Semester as a capstone, project driven, design course, with industry sponsorship.
Abstract: The paper reports on our NSF Combined Research Curriculum Development (CRCD) project to bring promising results of research conducted by the principal investigators, their industry partners, and other leading researchers from academia and industry into the design of novel sensing and control computing for automotive systems. A two-semester senior level course sequence is being developed and integrated into the electrical engineering and mechanical engineering curricula. One course is offered as a technical elective in the Fall semester, while the second course is offered in the Spring Semester as a capstone, project driven, design course, with industry sponsorship. The research to be transferred to the classroom addresses complete, project driven, course activities that span problem definition, modeling, simulation, and eventual real time interface and control implementation.