A view on limit cycle bifurcations in relay feedback systems

The paper is concerned with the study of oscillations in linear dynamic systems with relay feedback. The specific interest is about the bifurcations of these periodic solutions, with regard to phenomena which also occur in smooth systems and to others due to the relay discontinuity. The followed approach moves from the describing function method, leading to results which are approximate in nature but which express in a simple and correct way the essential mechanisms of the studied phenomena, as shown in the proposed examples.