Showing papers by "Hassan K. Khalil published in 1992"
TL;DR: In this article, an observer-based controller is designed to stabilize a fully linearizable nonlinear system, where the system is assumed to be left-invertible and minimum-phase.
Abstract: An observer-based controller is designed to stabilize a fully linearizable nonlinear system. The system is assumed to be left-invertible and minimum-phase. The controller is robust to uncertainties in modelling the nonlinearities of the system. The design of the controller and the stability analysis employs the techniques of singular perturbations. A new ‘Tikhonov-like’ theorem is presented and used to analyse the system when the control is globally bounded.
784 citations
TL;DR: In this article, a linearizing feedback control is derived in terms of some unknown nonlinear functions, which can be modelled by layered neural networks and the weights of the networks are updated and used to generate the control.
Abstract: Layered networks are used in a nonlinear adaptive control problem. The plant is an unknown feedback-linearizable discrete-time system, represented by an input-output model. A state space model of the plant is obtained to define the zero dynamics, which are assumed to be stable. A linearizing feedback control is derived in terms of some unknown nonlinear functions. To identify these functions, it is assumed that they can be modelled by layered neural networks. The weights of the networks are updated and used to generate the control. A local convergence result is given. Computer simulations verify the theoretical result.
400 citations
16 Dec 1992
TL;DR: In this paper, the stabilization of a class of multivariable nonlinear systems, about an equilibrium point at the origin, using output feedback is considered, and emphasis is placed on the class of systems that can be transformed into a global normal form with no zero dynamics.
Abstract: The stabilization of a class of multivariable nonlinear systems, about an equilibrium point at the origin, using output feedback is considered. Emphasis is placed on a class of systems that can be transformed into a global normal form with no zero dynamics. Semiglobal stabilization means that for every compact set of initial conditions, it is possible to design an output feedback controller that stabilizes the origin and includes the given compact set in the region of attraction. The system equations are allowed to depend on constant unknown parameters that do not change the vector relative degree of the system. The controller is robust with respect to these parameters. Global Lipschitz conditions are not required. >
111 citations
01 Jul 1992
TL;DR: In this article, a sequential procedure is described to decompose the problem into slow and fast subproblems, and a composite compensator is formed as the parallel connection of the fast compensator with the strictly proper part of the slow compensator.
Abstract: H∞ control of linear time-invariant singularly perturbed systems is considered. A sequential procedure is described to decompose the problem into slow and fast subproblems. The fast problem is solved first. Then the slow problem is solved under a constraint on the value of the compensator at infinity. A composite compensator is formed as the parallel connection of the fast compensator with the strictly proper part of the slow compensator. The asymptotic validity of the composite compensator is established.
57 citations