Frequency domain criteria for l/sup p/-robust stability of continuous linear systems

Necessary and sufficient criteria in the frequency domain for robust stability are given under the assumption that coefficients of a characteristic polynomial belong to a transformed l/sup p/-ball. Three cases are considered in detail: p= infinity (interval uncertainty), p=2 (ellipsoidal uncertainty), and p=1 (octahedral uncertainty). It is shown that frequency-domain-stability criteria are efficient when one deals with robust stability problems. The frequency-domain approach considered can be extended to various problems of robust stability.>