Open AccessMV bound and MV controller for convex‐non‐linear systems with input constraints
Author(s) -
Alipouri Yousef,
Huang Biao,
Kodamana Hariprasad
Publication year - 2018
Publication title -
iet control theory and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.059
H-Index - 108
eISSN - 1751-8652
pISSN - 1751-8644
DOI - 10.1049/iet-cta.2017.0760
Subject(s) - control theory (sociology) , benchmark (surveying) , controller (irrigation) , convergence (economics) , convex optimization , linear system , computer science , stability (learning theory) , upper and lower bounds , mathematical optimization , linear programming , limit (mathematics) , regular polygon , variance (accounting) , computation , mathematics , control (management) , algorithm , mathematical analysis , business , geometry , geodesy , accounting , artificial intelligence , machine learning , economic growth , agronomy , economics , biology , geography
To assess the performance of a control loop based on the minimum variance (MV) benchmark, we need to calculate MV lower bound (MVLB). Even though there is a plethora of literature available for calculating MVLB for the linear systems, these methods are not suitable for non‐linear systems. Furthermore, almost all of the real‐world applications have been encountered with input variance constraints. These constraints limit controllers' abilities in decreasing the output variability. Therefore, existing MVLB computation methods, which do not account for input constraints, are not realistic when applied to constrained systems. The authors propose a novel approach to estimate MVLB by employing properties of dual Lagrangian functions to address these issues simultaneously in this study. Furthermore, to design the constrained non‐linear MV controller (MVC), they propose to use the recurrent neural network for accommodating non‐linearities and the input constraints. Then, control loop stability, optimality with respect to MVLB as well as the global convergence of the proposed controller are analytically proved for convex‐non‐linear systems with input constraints. The proposed control strategy is verified through simulations performed on a non‐linear quadruple‐tank system. The results indicate that the proposed design provides satisfactory results in decreasing output variance while satisfying the constraints.