Adaptive output regulation of a class of discrete-time nonlinear systems based on output feedback and NN feedforward control

In this paper, a design method for adaptive output tracking control of discrete-time nonlinear systems is dealt with. The proposed method ensures the stability of the resulting control system by an adaptive output feedback based on OFSP properties of the controlled system and achieves the output tracking by an adaptive NN feedforward control. Since the discrete-time OFSP system must have a relative degree of 0, it possibly results in the causality problem. We will solve this problem by considering an equivalent control using the available output signals and develop an adaptive output feedback control system with an adaptive NN feedforward. The stability of the obtained control system will be analyzed through the discrete-time nonlinear version of KYP lemma.