eprintid: 2477 rev_number: 6 eprint_status: archive userid: 6 dir: disk0/00/00/24/77 datestamp: 2015-01-13 14:34:09 lastmod: 2015-11-02 09:57:27 status_changed: 2015-01-13 14:34:09 type: article metadata_visibility: show creators_name: Cerone, Vito creators_name: Piga, Dario creators_name: Regruto, Diego creators_id: creators_id: dario.piga@imtlucca.it creators_id: title: Characteristic polynomial assignment for plants with semialgebraic uncertainty: a robust diophantine equation approach ispublished: pub subjects: QA75 divisions: CSA full_text_status: none keywords: robust coprimeness, robust characteristic polynomial assignment, semialgebraic uncertainty, sum-of-square decomposition note: Article first published online: 9 SEP 2014 abstract: In this paper, we address the problem of robust characteristic polynomial assignment for LTI systems whose parameters are assumed to belong to a semialgebraic uncertainty region. The objective is to design a dynamic fixed-order controller in order to constrain the coefficients of the closed-loop characteristic polynomial within prescribed intervals. First, necessary conditions on the plant parameters for the existence of a robust controller are reviewed, and it is shown that such conditions are satisfied if and only if a suitable Sylvester matrix is nonsingular for all possible values of the uncertain plant parameters. The problem of checking such a robust nonsingularity condition is formulated in terms of a nonconvex optimization problem. Then, the set of all feasible robust controllers is sought through the solution to a suitable robust diophantine equation. Convex relaxation techniques based on sum-of-square decomposition of positive polynomials are used to efficiently solve the formulated optimization problems by means of semidefinite programming. The presented approach provides a generalization of the results previously proposed in the literature on the problem of assigning the characteristic polynomial in the presence of plant parametric uncertainty. date: 2014 date_type: published publication: International Journal of Robust and Nonlinear Control volume: 25 number: 16 publisher: Wiley-Blackwell pagerange: 2911-2921 id_number: 10.1002/rnc.3238 refereed: TRUE issn: 1049-8923 official_url: http://dx.doi.org/10.1002/rnc.3238 citation: Cerone, Vito and Piga, Dario and Regruto, Diego Characteristic polynomial assignment for plants with semialgebraic uncertainty: a robust diophantine equation approach. International Journal of Robust and Nonlinear Control , 25 (16). pp. 2911-2921. ISSN 1049-8923 (2014)