In this study, a novel identification technique, that is high-gain observer-based identification approach, is proposed for systems with bounded process and measurement noises. For system parameters with abnormal changes, an adaptive change detection and parameter identification algorithm is next presented. The presented technique and algorithm are finally applied to the parameter identification of the gas turbine engine by using the recorded input data from the engine test-bed. The identified parameters and the response curves are desirable. The simulations have proved the effectiveness of the proposed procedure compared with the previous identification approach.

For systems with both state and input time delays, a novel state and sensor fault observer is proposed in this paper to estimate system states and sensor faults simultaneously. In this design, a descriptor system approach and a linear matrix inequality technique are adopted, where the considered sensor fault may be in any form, even unbounded. Unbounded sensor faults will make the system fail unavoidably; it is indispensable to derive a reliable control scheme against sensor failures. Using the estimated state and sensor fault, a reliable observer-based controller is proposed, which makes the system work well nomatter whether sensor faults occur or not. The present approaches are next extended to the case for systems with multiple time delays. Finally, a simulation example of the network of three cascaded reactors is used to illustrate the design procedure and demonstrate the efficiency of the present techniques.

For dynamic systems with actuator faults, sensor faults, input disturbances and measurement noises, a novel high-gain estimation technique is presented in this paper to estimate system states, actuator faults and sensor faults simultaneously. The key idea is to represent faults as auxiliary system states so that a descriptor system representation can be formulated. By using the estimated state and fault signals,a fault-tolerant controller design approach is developed, where the closed-loop dynamic system can still be guaranteed to operate normally when actuator and sensor faults occur. It has been shown that in the proposed design framework,the actuator fault, sensor fault, input disturbance and measurement noise can appear simultaneously and can be allowed to be in different bounded forms. Finally, the proposed algorithm is applied to the simulation study of a three-shaft gas turbine system and desired results have been obtained.

For descriptor systems with measurement output noises (input disturbances may exist at the same time), a new descriptor estimator technique is developed. The necessary and sufficient condition for the existence of the present estimator is derived, and a systematic design approach is addressed. The effect of uncertainties is decoupled completely, and the asymptotic estimates of the descriptor system state and the output noise are obtained simultaneously. Furthermore, a normal state/disturbance estimator is also given. For a class of nonlinear descriptor systems with both output noises and input uncertainties, a nonlinear descriptor estimator is derived by using the proposed design approach, together with the linear matrix inequality technique. The existence and convergence of the nonlinear descriptor estimator is proven. The asymptotic estimates of the descriptor nonlinear system state and the output noise are obtained at the same time. The present estimators are applied to the sensor fault diagnosis, and hence the sensor fault can be estimated asymptotically. Finally, two numerical examples are included to illustrate the proposed design procedures and applications.

Doubly coprime factorization plays an important role in dealing with multivariable control problems using a factorization approach. In this study, based on an arbitrary and properly stabilizing controller,a general formula of doubly coprime factorization is obtained for use in descriptor systems. Detailed results have been derived on bridging the factorization approaches previously vailable in the literature.