The tracking problem of systems is one that has come under a lot of investigation. The initial studies were on the transfer function models of the system, based on internal model control [23], which used the inverse dynamics of the system to design a tracking controller. The problem with this simple logic arouse in cases wherein the system was nonminimum phase, i.e., had unstable zeros. In such a case, the inverse dynamics were unstable, which generated a closed loop system that may be stable, but was not internally stable [1]. Further study on the topic brought into light numerous techniques that handled the tracking problem, for both linear [5, 43] and nonlinear systems [16, 17, 32]. The research on unstable zero dynamics was also extended to discrete-system representations [26, 59]. © Springer-Verlag Berlin Heidelberg 2006.