A New Structured Multimodel Control of Nonlinear Systems by Integrating Stability Margin and Performance

Ahmadi, Mahdi; Haeri, ءMohammad

doi:10.1115/1.4036069

Cited by 9 publications

(54 citation statements)

References 29 publications

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“…In this regard, Du and Johansen 24,25 untie this issue by employing the correlation between gap metric and stability margin; however, it is required to design local controllers for all local models which makes it time-consuming procedure specially when the system is highly nonlinear and the number of local models is large. In the study by Ahmadi and Haeri, 26,27 an optimization problem is defined to integrate NLMs selection and local controllers design where stability, performance, and gap metric have been incorporated as well. In addition, an updating distance threshold is introduced that supports designing local controllers only for NLMs that leads to a faster procedure in comparison to Du et al 23–25 In the study by Ahmadi et al, 17 NLMs selection and local controllers design are integrated in which stability and performance have been assured in two decoupled loops.…”

Section: Introductionmentioning

confidence: 99%

An integrated best–worst decomposition approach of nonlinear systems using gap metric and stability margin

Ahmadi

Haeri

2020

Proceedings of the Institution of Mechanical Engineers, Part I:

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This article uses gap metric method to design a multi-model controller for nonlinear systems. In order to decompose the nonlinear system into a reduced nominal local models bank as much as possible, and assure the closed-loop robust stability and performance, the decomposition and designing of local controllers are integrated. To this end, robust stability, performance, and gap metric are incorporated to build a binary distance matrix that supports defining the driving and dependence powers for each local model. Then a best–worst analysis is employed considering the driving and dependence powers to find out the nominal local models. The proposed approach screens the value of all local models to choose each nominal local model. As a result, the global multi-model controller has a simple structure and avoids the computational complexity issues. To evaluate the effectiveness of the proposed method, two highly nonlinear systems, pH neutralization and continuous stirred tank reactor process, are simulated.

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Section: Introductionmentioning

confidence: 99%

An integrated best–worst decomposition approach of nonlinear systems using gap metric and stability margin

Ahmadi

Haeri

2020

Proceedings of the Institution of Mechanical Engineers, Part I:

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“…In the third category, both stability and performance are incorporated and considered concurrently to design the global multi-model controller (Ahmadi and Haeri, 2017, 2018; Du and Johansen, 2014b; Salah et al, 2016a, 2016b). In Salah et al (2016b), a new approach is presented to identify intermediate equilibrium points when the first and last ones are known.…”

Section: Introductionmentioning

confidence: 99%

“…However, due to direct interaction between stability margin and the performance, it would be difficult to incorporate them in this method. Ahmadi and his colleague have addressed a systematic procedure to design multi-model controllers by integrating stability and performance requirements (Ahmadi and Haeri, 2017). Selecting nominal local linear models bank and designing the related local controllers are done integrated based on an optimization problem.…”

Section: Introductionmentioning

confidence: 99%

“…In contrary to Ahmadi and Haeri (2017, 2018), Du and Johansen (2014b), Salah et al (2016a, 2016b), the integration of stability and performance was done in two independent steps which is a good deal with complexity of the decomposition step.…”

Section: Introductionmentioning

confidence: 99%

“…In contrary to Ahmadi and Haeri (2017), the local controllers in the decomposition step has a simpler structure. Therefore, the nominal local models selection procedure can be done faster.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A multi-model control of nonlinear systems: A cascade decoupled design procedure based on stability and performance

Ahmadi

Rikhtehgar

Haeri

2019

Transactions of the Institute of Measurement and Control

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Recently, the multi-model controllers design was proposed in the literature based on integrating of the stability and performance criteria. Although these methods overcome the redundancy problem, the decomposition step is very complex and time consuming. In this paper, a cascade design of multi-model control is presented that is made from two sequential steps. In the first step, the nonlinear system is decomposed into a set of linear subsystems by just considering the stability criterion. In this step, the gap metric is used as a smart tool to measure the distance between linear subsystems. While the closed-loop stability is gained through the first step, the performance is improved in the second step by adding internal model controllers in a cascade structure. Therefore, the proposed idea supports designing a multi-model controller in a simple way by integrating the stability and performance criteria in two independent cascade steps. As a result, the proposed method avoids the model redundancy problem, has a simple structure, guarantees the robust stability, and improves the performance. Two nonlinear chemical processes are simulated to evaluate the proposed multi-model controller approach.

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Robust multi‐model controllers design without impulse in switching times for non‐linear vibrations suppression of sandwich plate

Zazerani

Faraji

mohammadimehr

2022

IET Control Theory & Appl

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Generally multi-model controllers design has three stages: Decomposition of complicated non-linear systems into local linear models, designing the local controllers, and composition of them in sub-regions. In the present paper an algorithm is proposed in which all the three stages are simultaneously done to decrease the number of controllers. Determining a specific threshold based on non-linear model characteristics is a good criterion for this purpose. The threshold depends on the knowledge of the system features and designing method, and the improper selection of the threshold will increase the number of local models and the complexity of the global controller structure. This non-convex optimization problem is solved by the genetic algorithm whose cost function is defined by the complementary sensitivity function to guarantee the robust stability and optimal performance of the close loop the system, respectively. Another challenge in designing multi-model controllers is the transient performance degradation when switching from one local model to another. In the present research, the problem is solved by the system input generated by the online controller error signal and the feedback coefficient of the offline controller. The proposed robust controller in the presence of the uncertainties is evaluated for vibration suppression of a sandwich plate.

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A New Structured Multimodel Control of Nonlinear Systems by Integrating Stability Margin and Performance

Cited by 9 publications

References 29 publications

An integrated best–worst decomposition approach of nonlinear systems using gap metric and stability margin

An integrated best–worst decomposition approach of nonlinear systems using gap metric and stability margin

A multi-model control of nonlinear systems: A cascade decoupled design procedure based on stability and performance

Robust multi‐model controllers design without impulse in switching times for non‐linear vibrations suppression of sandwich plate

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