This paper discusses the problem of designing stabilizing controllers for uncertain symmetric composite systems. A procedure of designing a linear (decentralized) feedback control law which will stabilize a given symmetric composite system with uncertainty is presented by using the Riccati equation approach. A feature of the procedure is that the stabilizing control law can be conducted by solving two lower-order Riccati equations (or inequalities). The uncertainties considered in the systems may be time-varying. However, the values of the uncertaintics are constrained to lie within some known admissible bounds.

This paper discusses a class of large-scale systems composed of several similar subsystems interconnected with an external system in a symmetrical fashion. A method of determining the set of fixed modes of such a system with respect to decentralized (or partly decentralized) control is presented in terms of the modified subsystems. The completeness of these systems is studied, and a simple condition for such a system to be complete is derived.

This note is concerned with the problem of a robust non-fragile Kalman filter design for a class of uncertain linear systems with norm-bounded uncertainties. The designed state estimator can tolerate multiplicative uncertainties in the state estimator gain matrix. The robust nonfragile state estimator designs are given in terms of solutions to algebraic Riccati equations. The designs guarantee known upper bounds on the steady-state error covariance. A numerical example is given to illustrate the results.

This paper considers the problem of decentralized H∞ controller design via measurement feedback for linear composite systems. Two decentralized controller design procedures are presented in terms of positive definite solutions to modified algebraic Riccati inequalities. The resulting controllers guarantee closed-loop stability and an H∞-norm bound on disturbance attenuation. A numerical example is given to illustrate the design procedures.

This paper is concerned with the single-contingency reliable controller design problem for nonlinear systems. A procedure for designing reliable nonlinear controllers is presented for nonlinear systems with strictly redundant sensors and strictly redundant actuators. The resulting closed-loop nonlinear systems are reliable in the sense that they provide guaranteed local internal stability and H∞ performance not only when all sensors and actuators are operational but also when any one, but only one, sensor or actuator experiences an outage. An example is given to illustrate the design procedure and the effectiveness of the proposed methods.