A New Stability Theory for Grünwald–Letnikov Inverse Model Control in the Multivariable LTI Fractional-Order Framework

The new general theory dedicated to the stability for LTI MIMO, in particular nonsquare, fractional-order systems described by the Grünwald−Letnikov discrete-time state−space domain is presented in this paper. Such systems under inverse model control, principally MV/perf...

Full description

Bibliographic Details
Main Authors: Wojciech Przemysław Hunek, Łukasz Wach
Format: Article
Language:English
Published: MDPI AG 2019-10-01
Series:Symmetry
Subjects:
Online Access:https://www.mdpi.com/2073-8994/11/10/1322
Description
Summary:The new general theory dedicated to the stability for LTI MIMO, in particular nonsquare, fractional-order systems described by the Gr&#252;nwald&#8722;Letnikov discrete-time state&#8722;space domain is presented in this paper. Such systems under inverse model control, principally MV/perfect control, represent a real research challenge due to an infinite number of solutions to the underlying inverse problem for nonsquare matrices. Therefore, the paper presents a new algorithm for fractional-order perfect control with corresponding stability formula involving recently given <i>H</i>- and <inline-formula> <math display="inline"> <semantics> <mi>&#963;</mi> </semantics> </math> </inline-formula>-inverse of nonsquare matrices, up to now applied solely to the integer-order plants. On such foundation a new set of stability-related tools is introduced, among them the key role played by so-called control zeros. Control zeros constitute an extension of transmission zeros for nonsquare fractional-order LTI MIMO systems under inverse model control. Based on the sets of stable control zeros a minimum-phase behavior is specified because of the stability of newly defined perfect control law described in the non-integer-order framework. The whole theory is complemented by pole-free fractional-order perfect control paradigm, a special case of fractional-order perfect control strategy. A significant number of simulation examples confirm the correctness and research potential proposed in the paper methodology.
ISSN:2073-8994