Output control of discrete-time nonlinear systems

Output tracking control of a general class of nonlinear sampled-data systems is considered. A novel block input-output realization of the plant is first introduced that transforms the system into one with equal number of inputs and states. This realization is subsequently used to formulate an output feedback controller for regulation or tracking. The proposed controller only requires measurement of the system´s outputs, and is applicable to both minimum and nonminimum phase plants of arbitrary relative degree. For applications involving a finite-duration or periodic desired outputs, an iterative algorithm is proposed to learn the feedforward input. Finally, a simulation example is presented to further illustrate and evaluate the performance of the proposed control scheme.