Off-axis circle criteria for Lur´e systems with interval plants

Considerable attention has been paid recently to absolute stability property of Lur´e systems involving interval plants and to date several theorems are available for checking the stability. This paper presents some more results that join in these line of researches. Namely, a method is proposed to check the absolute stability of Lur´e systems with interval plants and monotonic nonlinearities via an off-axis circle criterion. The nonlinearities are those whose incremental characteristics lies in a sector. As in the previous work, it is shown that only sixteen systems corresponding to extreme plants suffices need to be checked. An example is provided to illustrate the applicability of the results