## Abstract

In the last chapter, we considered the problem of minimizing **F** _{zw} with respect to the *H* _{ 2 } norm. The performance specifications were given in the time domain. As we have seen in Chap. 3 for SISO problems, for specifications in the frequency domain the *H* _{ ∞ } norm is an adequate tool. In this way we are naturally lead to the question of how controllers can be characterized in a way which minimizes the closed-loop transfer function **F** _{zw} with respect to the *H* _{ ∞ } norm. There are two important methods for solving this problem. One is based on two Riccati equations similar to those used in the *H* _{ 2 } problem. It will be analyzed in this chapter, whereas the other method uses linear matrix inequalities and is presented in the next chapter.

## Keywords

Riccati Equation Output Feedback Imaginary Axis Optimal Controller Characterization Theorem## Preview

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## Notes and References

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