qChapter 8 derives robust stability tests for systems under various modeling
assumptions through the use of the small gain theorem. In
particular, we show that a system shown below, with an
unstructured uncertainty *D* Î*R**H**¥* with *||**D**||**¥** **<1*, is robustly stable if
and only if *||T**zw**||**¥** **£**1* , where *T**zw* is the
matrix transfer function from *w *to *z.
*

Chapter
8