62 CHAPTER 2. OVERVIEWOF THE UNDERLYING THEORY
Figure 2.12: D-Kiteration procedure: a)Design H∞(or other) controller: K0(s)[step
i)]. b) Closed loop perturbed system for µanalysis [step ii)]. c)Frequency by frequency
upper bound D(ω) scale approximation to µanalysis [step iii)]. d)Scaling of H∞design
problem by ˆ
D(s)whereˆ
D(ω )≈D(ω)[stepsiv)&v)].