Robust stabilization: some extensions of the gain margin maximization problem

Considers robust stabilization for SISO systems with linear dependence on a real uncertain parameter which may occur either in the numerator or denominator of the plant transfer function. The authors show necessary and sufficient conditions for the existence of robust controllers. Their structure and parameterization can be obtained from the corresponding Nevanlinna-Pick interpolation problems. This work extends the previously known case of an uncertain gain parameter