On zero relocation in adaptive control of plants with structured uncertainties

The present paper deals with the solution to the following problem: Given a linear time invariant (LTI) system transfer function whose numerator and denominator polynomial coefficients range in known intervals find a first order LTI filter such that when placed in parallel with the system the resulting augmented plant is minimum phase. This problem is of some interest in applications of adaptive control of nonminimum phase plants and, to the best of the authors' knowledge, remained open in the literature.<
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