Criteria for chaotic behavior by perturbed lag elements

This paper proposes a technique for evaluating the presence of chaos in the case that chaotic nonlinear feedback systems are slightly perturbed by uncertain elements. The main strategy of the proposed technique is to treat the perturbation effects on systems as those on limit cycles estimated by the describing function method. This paper considers two types of perturbing element, 1st and 2nd order lag elements, on the Brockett chaotic system (1982) and then provides an analytical technique for the problem addressed