Output transformations and separation results for feedback linearizable delay systems

The class of strict-feedback systems enjoys special properties that make it similar to linear systems. This paper proves that such a class is equivalent, under a change of coordinates, to the wider class offeedback linearizable systems with multiplicative input, when the multiplicative terms are functions ofthe measured variables only. We apply this result to the control problem of feedback linearizable nonlinear MIMO systems with input and/or output delays. In this way, we provide sufficient conditions under whicha separation result holds for output feedback control and moreover a predictor-based controller exists. When these conditions are satisfied we obtain that the existence of stabilizing controllers for arbitrarily large delays in the input and/or the output can be proved for a wider class of systems than previously known.