A composite circle criterion

Donatello Materassi, Giacomo Innocenti, Roberto Genesio, Michele Basso

Abstract: The paper deals with the classical problem of the absolute stability in a SISO Lur'e system. The circle criterion is applied to different overlapping sectors and then, for all the functions in the 'union sector', a set of constraints is defined, so that they make globally asymptotically stable the closed loop system. The conclusion is that in every sector, such that can be covered by subsectors the circle criterion can be applied to, it is possible to define a class of nonlinearities, which solve the absolute stability problem.