This paper is concerned with the problem of non-fragile H∞ controller design for linear time-invariant systems. The controller to be designed is assumed to have multiplicative gain variations. Design methods are presented in terms of symmetric positive-definite solutions of algebraic Riccati inequalities. The resulting design is such that the closed-loop system is robustly stable and has an H∞ disturbance attenuation bound with respect to the multiplicative controller gain variations. A numerical example is given to illustrate the design methods.

This paper considers the decentralized H∞-controller design problem for nonlinear systems. Sufficient conditions for the solution of the problem are presented in terms of solutions of Hamilton-Jacobi inequalities. The resulting design guarantees local asymptotic stability and ensures a predetermined L2-gain bound on the closed-loop system.

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 considers the problem of guaranteed cost control for discrete-time linear systems under state feedback control gain perturbations. Two classes of perturbations are considered, namely, additive and multiplicative. The state feedback control designs for optimal guaranteed cost control under the two classes of gain perturbations are given in terms of solutions to algebraic Riccati equations. The designs are such that the cost of the closed-loop system is guaranteed to be within a certain bound for all admissible uncertainties. Numerical examples are included to illustrate the design procedures.

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.