Showing papers by "Hassan K. Khalil published in 1993"

Semiglobal stabilization of a class of nonlinear systems using output feedback

Abstract: The stabilization of a class of multivariable nonlinear systems, about an equilibrium point at the origin, using output feedback, is considered. In particular, a class of systems which can be transformed into a global normal form with no zero dynamics is treated. Semiglobal stabilization means that for every compact set of initial conditions, an output feedback controller that stabilizes the origin and includes the given compact set in the region of attraction can be designed. The system equations are allowed to depend on constant unknown parameters which do not change the vector relative degree of the system, and the controller is robust with respect to these parameters. Global Lipschitz conditions are not required. >

Output feedback stabilization using variable structure control

Abstract: Considers the stabilization of a class of multivariable nonlinear systems, about an equilibrium point at the origin, using variable structure output feedback control. In particular, the system can be transformed into a normal form with no zero dynamics. A robust high-gain observer is used to estimate the state variables while rejecting error disturbances. A globally bounded discontinuous variable structure controller is designed to compensate for modeling error. The authors show that the controller can stabilize the closed-loop system and does not suffer from the peaking phenomenon which exists in previous designs. >

Asymptotic Regulation of Minimum Phase Nonlinear Systems Using Output Feedback

Abstract: We consider a single-input single-output (SISO) nonlinear system which has a well defined normal form with asymptotically stable zero dynamics. We allow the system's equation to depend on bounded uncertain parameters which do not change the relative degree. Our goal is to design an output feedback controller which regulates the output to a constant reference in the presence of constant unkown input disturbances. The disturbance vector fields satisfy geometric conditions which ensure that the system is transformable into the so called disturbance-strict-feedback form. The integral of the regulation error is augmented to the system equation and a robust output feedback controller is designed to bring the state of the closed-loop system to a positively invariant set. Once inside this set, the trajectories approach a unique equilibrium point at which the regulation error is zero. We give regional as well as semi-global results.