New applications of mu to real-parameter variation problems

The structured singular value (SSV) has been used in recent studies of the robust stability of feedback systems subject to real-parameter variations. In this paper, we summarize the results obtained when some new upper-bounds on the SSV for real-parameters (reference [1]) were used in two studies of flight control systems. The perturbation structure for higher rank perturbations is discussed and the issue of lower-bounds for the SSV in the real-parameter problem is considered. A new theoretical result relevant to lower-bounds in a special case is given.