Comparison of noncausal inversion techniques for discrete time linear systems: application to a flexible link

In this paper, the problem of stable inversion of nonminimum phase discrete-time system is considered. In particular, three inversion techniques presented in the literature are compared and their results discussed. It is shown that these techniques, aiming at achieving the perfect tracking of a given reference signal, can be considered equivalent for specific plants. In this manner, their peculiarities and design objectives can be indifferently applied to the three approaches. More in general, design and performance features of each method are pointed out, defining a common framework for both linear and nonlinear systems.