Convergence of the signed output error adaptive identifier

The authors consider an adaptive output error identifier with a signum function in its update kernel. It is shown that the classical strictly positive real (SPR) condition required for the convergence of traditional adaptive identifiers is not enough but that a stronger operator condition called the strict dominant passivity (SDP) condition is needed. An analog of the Kalman Yakubovic Popov lemma is given for the SDP condition, and it is used to outline a convergence proof