Gradient vs. Non-Gradient-Based Model Free Control Algorithms: Analysis and Applications to Nonlinear Systems

Against the background of the development of control systems, Data Driven Control (DDC) methods are becoming more and more popular, given the system’s independence from physical models and the possibility of quickly tuning the controller. The usefulness of such tuning algorithms increases with the c...

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Main Authors: Andrei Baciu, Corneliu Lazar
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Applied Sciences
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Online Access:https://www.mdpi.com/2076-3417/15/5/2766
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author Andrei Baciu
Corneliu Lazar
author_facet Andrei Baciu
Corneliu Lazar
author_sort Andrei Baciu
collection DOAJ
description Against the background of the development of control systems, Data Driven Control (DDC) methods are becoming more and more popular, given the system’s independence from physical models and the possibility of quickly tuning the controller. The usefulness of such tuning algorithms increases with the complexity of the plants. Nonlinear models are the main class of processes for which such laws are amenable. According to the literature, a class of DDC methods exist that perform online estimation of plant behavior with an unknown structure, which is generically called Model Free. This title is assumed by two types of algorithms, which contain it in the name. One is the gradient-based algorithm, Model Free Adaptive Control, defined by Hou, which uses the concept of dynamic linearization through pseudo partial derivatives (PPD) and pseudo gradient (PG). The other is a non-gradient based algorithm, Model Free Control, defined by Fliess and Join, which uses the concept of the ultralocal model and intelligent PID controllers (iPID). For the gradient-based methods, in the compact form of dynamic linearization (CFDL), i.e., partial form dynamic linearization (PFDL), two algorithms are proposed to determine the initial value of the time-varying parameters PPD and PG from the dynamic performance perspective as they offer the best responses. The CFDL and PFDL variants of the MFAC control law, which have parameters that result from the application of the proposed algorithms, are compared with iP and iPD controllers on nonlinear control systems.
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spelling doaj-art-dc8c7fa3ed6c4e3783b1670cabdfbb3c2025-08-20T02:59:07ZengMDPI AGApplied Sciences2076-34172025-03-01155276610.3390/app15052766Gradient vs. Non-Gradient-Based Model Free Control Algorithms: Analysis and Applications to Nonlinear SystemsAndrei Baciu0Corneliu Lazar1Department of Automatic Control and Applied Informatics, “Gheorghe Asachi” Technical University of Iasi, 700050 Iasi, RomaniaDepartment of Automatic Control and Applied Informatics, “Gheorghe Asachi” Technical University of Iasi, 700050 Iasi, RomaniaAgainst the background of the development of control systems, Data Driven Control (DDC) methods are becoming more and more popular, given the system’s independence from physical models and the possibility of quickly tuning the controller. The usefulness of such tuning algorithms increases with the complexity of the plants. Nonlinear models are the main class of processes for which such laws are amenable. According to the literature, a class of DDC methods exist that perform online estimation of plant behavior with an unknown structure, which is generically called Model Free. This title is assumed by two types of algorithms, which contain it in the name. One is the gradient-based algorithm, Model Free Adaptive Control, defined by Hou, which uses the concept of dynamic linearization through pseudo partial derivatives (PPD) and pseudo gradient (PG). The other is a non-gradient based algorithm, Model Free Control, defined by Fliess and Join, which uses the concept of the ultralocal model and intelligent PID controllers (iPID). For the gradient-based methods, in the compact form of dynamic linearization (CFDL), i.e., partial form dynamic linearization (PFDL), two algorithms are proposed to determine the initial value of the time-varying parameters PPD and PG from the dynamic performance perspective as they offer the best responses. The CFDL and PFDL variants of the MFAC control law, which have parameters that result from the application of the proposed algorithms, are compared with iP and iPD controllers on nonlinear control systems.https://www.mdpi.com/2076-3417/15/5/2766Model Free ControlModel Free Adaptive Controlintelligent PID controllersgradient-based Model Free Control Algorithmsnon-gradient-based Model Free Controlnonlinear systems
spellingShingle Andrei Baciu
Corneliu Lazar
Gradient vs. Non-Gradient-Based Model Free Control Algorithms: Analysis and Applications to Nonlinear Systems
Applied Sciences
Model Free Control
Model Free Adaptive Control
intelligent PID controllers
gradient-based Model Free Control Algorithms
non-gradient-based Model Free Control
nonlinear systems
title Gradient vs. Non-Gradient-Based Model Free Control Algorithms: Analysis and Applications to Nonlinear Systems
title_full Gradient vs. Non-Gradient-Based Model Free Control Algorithms: Analysis and Applications to Nonlinear Systems
title_fullStr Gradient vs. Non-Gradient-Based Model Free Control Algorithms: Analysis and Applications to Nonlinear Systems
title_full_unstemmed Gradient vs. Non-Gradient-Based Model Free Control Algorithms: Analysis and Applications to Nonlinear Systems
title_short Gradient vs. Non-Gradient-Based Model Free Control Algorithms: Analysis and Applications to Nonlinear Systems
title_sort gradient vs non gradient based model free control algorithms analysis and applications to nonlinear systems
topic Model Free Control
Model Free Adaptive Control
intelligent PID controllers
gradient-based Model Free Control Algorithms
non-gradient-based Model Free Control
nonlinear systems
url https://www.mdpi.com/2076-3417/15/5/2766
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AT corneliulazar gradientvsnongradientbasedmodelfreecontrolalgorithmsanalysisandapplicationstononlinearsystems