2,013 results
Search Results
2. Fixed-Time $\mathcal {H}_{\infty }$ Control for Port-Controlled Hamiltonian Systems.
- Author
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Liu, Xinggui and Liao, Xiaofeng
- Subjects
HAMILTONIAN systems ,STATE feedback (Feedback control systems) ,PASSIVITY-based control ,CLOSED loop systems ,PAPER arts ,STABILITY criterion - Abstract
In this paper, the locally fixed-time and globally fixed-time $\mathcal {H}_{\infty }$ control problems for the port-controlled Hamiltonian (PCH) systems are investigated via the interconnection and damping assignment passivity-based control (IDA-PBC) technique. Compared with finite-time stabilization, where the convergence time of the closed-loop system's states relies on the initial values, the settling time of fixed-time stabilization can be adjusted to achieve desired equilibrium point regardless of initial conditions. The concepts of fixed-time $\mathcal {H}_{\infty }$ control, fixed-time stability region (or region of attraction), and fixed-time stability boundary are presented in this paper, and the criterions of globally fixed-time attractivity of a prespecified locally fixed-time stability region are obtained. Combining the locally fixed-time stability of an equilibrium point and the globally fixed-time attractivity of a prespecified fixed-time stability region, the globally fixed-time $\mathcal {H}_{\infty }$ control problem of PCH system is effectively solved. Two novel control laws are designed to deal with the globally fixed-time $\mathcal {H}_{\infty }$ control problem, and the conservativeness in estimating the settling time is also briefly discussed. An illustrative example shows that the theoretical results obtained in this paper work very well in the fixed-time $\mathcal {H}_{\infty }$ control design for PCH systems. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
3. Predictor-Based Neural Dynamic Surface Control of a Nontriangular System With Unknown Disturbances.
- Author
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Yang, Yang, Chen, Didi, Liu, Qidong, Zhang, Tengfei, Liu, Aaron, and Yue, Wenbin
- Subjects
NONLINEAR systems ,NOISE measurement ,APPROXIMATION error ,NONLINEAR dynamical systems ,CLOSED loop systems ,ADAPTIVE control systems ,BRUSHLESS electric motors - Abstract
For a class of nontriangular nonlinear systems in presence of unknown disturbances, we propose a predictor-based neural dynamic surface control (PNDSC) strategy in this paper. This nontriangular system is transformed via the mean value theorem, and a predictor is then constructed. To avoid an algebraic loop problem, partial state vectors are employed as input signals of neural networks (NNs) for approximating unknown dynamics, and compensation items are designed to compensate for approximation errors from NNs. Different from the traditional NDSC, the PNDSC in this paper utilizes prediction errors to update learning parameters for improving NNs’ learning behaviors with overlarge adaptive gains. On the basis of improved NNs’ approximation behaviors, a predictor-based NNs disturbance observer (PNNDO) is constructed for compensation for external disturbances and approximation errors from NNs. Furthermore, with predictors, a normalization method of weights is developed to reduce the number of online learning parameters. On the basis of the aforementioned result, measurement noises are taken into account in our predictor-based neural control strategy. We employ predictor states, rather than measurement information paralyzed by noises, in design of our control strategy. This reduces high-frequency oscillations in control input. A Lyapunov-based stability analysis shows that all signals are ultimately bounded in the closed-loop system. Finally, the effectiveness of the proposed control strategy is verified by a numerical example and a permanent magnet brushless DC motor system. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
4. Modified Repetitive Control Design for Nonlinear Systems With Time Delay Based on T–S Fuzzy Model.
- Author
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Sakthivel, Rathinasamy, Selvaraj, Palanisamy, and Kaviarasan, Boomipalagan
- Subjects
NONLINEAR systems ,LINEAR matrix inequalities ,TIME delay systems ,CLOSED loop systems ,STATE feedback (Feedback control systems) ,SYMMETRIC matrices - Abstract
In this paper, based on the Takagi–Sugeno fuzzy model approach, a novel output feedback control strategy is developed for a class of continuous-time nonlinear time delay systems via modified repetitive control scheme. The main objective of this paper is to design a fuzzy rule-based modified repetitive controller such that the system output can track any given periodic reference signal even in the presence of periodic disturbances. For this purpose, by employing fuzzy-dependent Lyapunov–Krasovskii functional together with the free-weighting matrix technique, a new set of sufficient conditions is presented in terms of linear matrix inequalities to guarantee the robust stability of the resulting closed-loop system. Based on these conditions and using internal model principle, it is shown that the system output tracks the given reference input within the desired error. Finally, two application-oriented examples are presented to validate the obtained theoretical results in which the proposed control design scheme gives better performance over the existing control scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
5. Suppression of Sub-Synchronous Resonances Through Excitation Control of Doubly Fed Induction Generators.
- Author
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Baesmat, Hana Jannaty and Bodson, Marc
- Subjects
INDUCTION generators ,ALTERNATING current generators ,RESONANCE ,REACTIVE power ,CLOSED loop systems ,SYSTEM analysis - Abstract
The paper considers the problem of sub-synchronous resonances (SSR) in doubly fed induction generators connected to the grid through series-compensated lines. The existence of oscillations is observed on a laboratory test-bed in various conditions, with instabilities developing in the worst-case scenario. Despite the limitations of a small-scale test-bed, the ability to investigate problems and solutions in ways that would not be possible on a full-scale system is very valuable. In particular, the paper demonstrates the significant effect of the choice of dq reference frame on the severity of SSR. Stator-aligned algorithms are found to be significantly more resonant than grid-oriented algorithms, as evidenced in experiments as well as using an analysis method proposed in the paper. From this observation, an algorithm is proposed to emulate a grid-alignment using stator voltages and currents, but without measurements of the grid and series-capacitor voltages. Two control laws are then presented to regulate the active and reactive powers generated, resulting in well-damped transient responses. SSR oscillations are found to be eliminated in experime, as well as simulations of a full-scale system and using a frequency response analysis of the closed-loop system. The effectiveness of the proposed control schemes is verified through experiments for different compensation levels and varying speeds. Within the assumptions made in the design, the proposed controllers are global. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
6. Quantized Fuzzy Output Feedback ${\mathcal{H}}_{\infty}$ Control for Nonlinear Systems With Adjustment of Dynamic Parameters.
- Author
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Chang, Xiao-Heng, Yang, Can, and Xiong, Jun
- Subjects
STATE feedback (Feedback control systems) ,FEEDBACK control systems ,NONLINEAR systems ,LINEAR matrix inequalities ,DYNAMICAL systems ,FUZZY systems ,QUANTIZATION (Physics) - Abstract
This paper investigates the output feedback $ {\mathcal {H}_{\infty }}$ control problem for a class of continuous-time nonlinear systems with both output and input quantization. The nonlinear plant is represented by a Takagi–Sugeno fuzzy model. The measurement output and the control input signals will be quantized by dynamic quantizers. The attention of this paper is focused on the design of the output feedback controller and quantizers such that the fuzzy closed-loop system is asymptotically stable and also achieves a prescribed $ {\mathcal {H}_{\infty }}$ noise attenuation level with respect to the effect of quantization. In the presence of quantization, two novel $ {\mathcal {H}_{\infty }}$ performance analysis criteria are presented for the considered fuzzy systems based on the descriptor representation approach. Then, sufficient conditions for the existence of the feedback $ {\mathcal {H}_{\infty }}$ controller gain and the quantizers’ dynamic parameters are expressed in terms of linear matrix inequalities. An adjusting scheme on quantizers’ parameters is proposed for the fuzzy system. Simulation examples are provided to show the effectiveness of the proposed design method. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
7. Robust PI-D Controller Design for Uncertain Linear Polytopic Systems Using LMI Regions and $H_2$ Performance*.
- Author
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Vesely, Vojtech and Korosi, Ladislav
- Subjects
STATE feedback (Feedback control systems) ,LINEAR time invariant systems ,LINEAR systems ,LINEAR matrix inequalities ,CLOSED loop systems ,SYNCHRONOUS generators - Abstract
The paper deals with the new design procedure for PID-D robust controller with state/output derivative feedback to stabilize the closed-loop system using linear matrix inequality (LMI) and LMI regions with common in the frame of $H_2$ performance quadratic cost functions known as $(Q,S,R)$. The designed robust controller ensures robust properties of the closed loop system for linear time invariant and linear time variant gain scheduled plant descriptor systems. The robust controller design procedure is based on the extended original derivative of Lyapunov function and to obtain the convex conditions with respect to uncertainties, gain scheduled variables, and ensures that proposed new method guarantees less conservativeness to the design procedure we have introduced using the auxiliary matrices. The obtained results should be utilized to design power system stabilizer for synchronous generators and so on. The obtained robust PI-D controller with output and state/output derivative feedback for uncertain polytopic systems ensures that all closed-loop eigenvalues are lying in the defined LMI region. Two examples illustrate the effectiveness of the new design procedure. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
8. Stabilizing Sets of Current PI Controllers for IM Drives With and Without LC Filter.
- Author
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Vaishnav, Navneet and Jain, Amit
- Subjects
SQUIRREL cage motors ,CLOSED loop systems ,IDEAL sources (Electric circuits) ,PULSE width modulation - Abstract
Connection of an LC filter to the output of voltage source inverter (VSI) in squirrel cage induction motor (SQIM) drive converts the pulse-width modulated (PWM) voltages into smooth sinusoidal voltages. However, this connection may lead to closed-loop instability in the rotor flux-oriented (RFO) vector-controlled (VC) SQIM system. The closed-loop stability of the combined SQIM + LC filter (SQLC) system is complex and has not been analyzed properly in the literature. In this paper, a detailed closed-loop stability analysis of the SQLC system has been presented based on stability region (SR) and accordingly the PI gains of VC has been designed. The SR method is adopted to derive the common stability regions for the SQIM system and SQLC system. Thereby, the paper proves that connecting an LC filter in-between the VSI and the SQIM system does not always destabilize the closed-loop system. Further, for an SQLC system, the complete range of current controller gains is obtained at various operating points. The frequency-domain specifications have been used to select a proper stabilizing set and the effect of parametric variation of LC filter on the stabilizing set has also been discussed. The experimental results are provided to validate the analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
9. Editorial: Launching Into 2018.
- Author
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Lehman, B. and Chung, H. S. H.
- Subjects
PULSE width modulation ,POWER electronics ,CLOSED loop systems - Published
- 2018
- Full Text
- View/download PDF
10. Event-Triggered Finite-Time Control for Networked Switched Linear Systems With Asynchronous Switching.
- Author
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Ren, Hangli, Zong, Guangdeng, and Li, Tieshan
- Subjects
FEEDBACK control systems ,ASYNCHRONOUS transfer mode ,MULTIAGENT systems - Abstract
This paper is concerned with the event-triggered finite-time control problem for networked switched linear systems by using an asynchronous switching scheme. Not only the problem of finite-time boundedness, but also the problem of input-output finite-time stability is considered in this paper. Compared with the existing event-triggered results of the switched systems, a new type of event-triggered condition is proposed. Sufficient conditions are established to guarantee the event-based asynchronous closed-loop systems are both finite-time bounded and input-output finite-time stable. A set of event-triggered finite-time bounded and input-output finite-time stabilizing controllers are designed under the asynchronous control scheme. It is revealed that the triggered thresholds determine the number of sampling points transmitted to the controller, and the smaller triggered parameters indicate the less-sampled data needed to be transmitted to the controller under the event-triggered scheme. Finally, a boost converter circuit is applied to bring out the advantages of the proposed control scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
11. Event-Based Security Control for Stochastic Networked Systems Subject to Attacks.
- Author
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Yan, Huaicheng, Wang, Jiangning, Zhang, Hao, Shen, Hao, and Zhan, Xisheng
- Subjects
STOCHASTIC systems ,CLOSED loop systems ,LINEAR matrix inequalities ,COST functions ,STOCHASTIC control theory - Abstract
This paper is concerned with the event-based security control problems for a set of discrete-time stochastic systems suffered from randomly occurred attacks, especially the denial-of-service attacks and the deception attacks. An attack model with compensation is established to describe combinations of attacks to the networked control systems. An event-triggered mechanism is employed to debase the communication load by transmitting measurement signals when a definite triggering condition is satisfied. A definition of security probability is proposed to describe the transient state of controller systems. The aim of this paper is to design a dynamic output feedback controller, thereupon the closed-loop system achieves the described security in probability. Some novel sufficient conditions are proposed to guarantee the input-to-state stability of the system in probability, and the controller gains are designed by solving a set of matrix inequalities. The upper bound of the quadratic cost function is also derived. Finally, simulation examples are applied to illustrate the effectiveness of the proposed design scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
12. Event-Based Fuzzy Adaptive Consensus FTC for Microgrids With Nonlinear Item via Prescribed Fixed-Time Performance.
- Author
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Liu, Guangliang, Sun, Qiuye, Wang, Rui, and Zhang, Huaguang
- Subjects
ADAPTIVE fuzzy control ,MICROGRIDS ,FAULT-tolerant control systems ,LYAPUNOV stability ,STABILITY theory ,CLOSED loop systems - Abstract
The device faults commonly exist in microgrids (MGs) and often undermine the system stability. However, the existing distributed methods generally design control protocols based on the absence of faults or only considering actuator faults, which limits the applicability of controllers in MG systems. Therefore, this paper investigates an adaptive prescribed fixed-time performance (PFTP) consensus fault-tolerant control (FTC) problem for the voltage regulation of a nonlinear islanded MG inverter-based distributed generators (DGs) with output contactor and actuator fault via the state event-triggered mechanism. The PFTP method for the voltage restoration synchronization error is proposed by constructing a novel performance function to increase the speed of voltage recovery. Based on the estimation properties of fuzzy logic system, an unknown nonlinear function and the residual term of output contactor are estimated. Then, an adaptive state event-triggering mechanism is designed to reduce the communication burden, and its main advantage is that the control protocol is updated in the aperiodic way at the triggering instants. Further, according to backstepping technology, a novel adaptive event-triggered consensus FTC protocol is constructed to achieve the voltage regulation of islanded MG, and a parameter adaptive law is designed to compensate the adverse effects of the output contactor fault. Based on the Lyapunov stability theory, it is proved that the voltage recovery synchronization error satisfies the PFTP, and all signals in the closed-loop systems are cooperatively uniformly ultimately bounded. Finally, the proposed control strategy is also validated by using the MATLAB. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
13. A BDI Modeling Approach for Decision Support in Supply Chain Quality Inspection.
- Author
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Yan, Jiaqi, Li, Xin, Sun, Sherry X., Shi, Yani, and Wang, Huaiqing
- Subjects
SUPPLY chains ,CLOSED loop systems ,REQUIREMENTS engineering ,DECISION support systems ,SUPPLY chain management ,MANUFACTURING processes - Abstract
Quality inspection, a widely adopted practice in supply chains, measures whether delivered products conform to prespecified quality requirements. Due to potential economic benefits, suppliers may deliberately manipulate products to falsify test results. However, unqualified products could cause severe problems in supply chains or even tragedies, such as China’s tainted milk scandal. In this paper, we propose a belief-desire-intention modeling approach to predict suppliers’ behavior and provide inspection suggestions to buyers to overcome the problem. Assuming access to the production process, our approach can represent suppliers’ knowledge of production and deception to mimic their reasoning processes and predict their deception intentions. This flexible approach can also adapt to environmental changes and deliver effective results. In this paper, we build a prototype system for supply chain quality inspections based on the proposed method. We conduct laboratory experiments to collect data for computational assessments of the performance of the prototype. It is shown that our proposed approach is more accurate than classic machine learning methods in detecting suppliers’ deceptions. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
14. Distributed Consensus of Linear Multiagent Systems: Laplacian Spectra-Based Method.
- Author
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Chen, Yuanye and Shi, Yang
- Subjects
MULTIAGENT systems ,LINEAR systems ,FREQUENCY-domain analysis ,CLOSED loop systems - Abstract
The consensusability problems of general linear multiagent systems considering directed topologies are explored from a frequency domain perspective in this paper. By investigating the properties of Laplacian spectra, a consensus criterion is established based on the stability of several complex weighted closed-loop systems. Furthermore, for single-input multiagent systems, frequency domain consensusability criteria are proposed on the basis of the stability margins, which depend on the $ {\mathcal {H}}_{\infty }$ norm of the complementary sensitivity function determined by the agents’ unstable poles. The corresponding design procedure is also developed. A numerical example is also presented to validate the proposed consensusability results. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
15. Stability of Wide-Area Power System Controls With Intermittent Information Transmission.
- Author
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Taousser, Fatima Zohra, Raoufat, M. Ehsan, Tomsovic, Kevin, and Djouadi, Seddik M.
- Subjects
CLOSED loop systems ,EXPONENTIAL stability ,INFORMATION resources management ,LINEAR systems ,NONLINEAR systems ,REQUIREMENTS engineering ,DISCRETE-time systems - Abstract
This paper investigates the stability problem of wide-area damping controllers with intermittent information transmission. Due to the interruption in communication links between remote measurements and damping controller or from the damping controller to the damping actuators, the closed-loop system might become unstable. The instability is strongly related to the duration of interruption of information transmission. To estimate instability, this paper formulates the problem as continuous/discrete-time switched system and the stability conditions are derived using time-scale theory. This method allows us to handle continuous and discrete dynamics as two pieces of the same framework, such that the system will switch between a continuous-time subsystem (when the communication occurs without any interruption) and a discrete-time subsystem (when the communication fails). The contribution is to estimate the maximum allowable value of the time of interruption of information transmission that does not violate the exponential stability of the closed-loop system. The findings are useful in specifying the minimum requirements for communication infrastructure and the time to activate remedial action schemes. Simulations are performed based on both linear and nonlinear systems to validate the theoretical development. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
16. Fault-Tolerant Resilient Control For Fuzzy Fractional Order Systems.
- Author
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Sakthivel, Rathinasamy, Ahn, Choon Ki, and Joby, Maya
- Subjects
MATRIX inequalities ,LINEAR matrix inequalities ,FRACTIONAL differential equations ,FAULT-tolerant computing ,STATE feedback (Feedback control systems) ,CONTINUOUS distributions ,DISTRIBUTION (Probability theory) ,CLOSED loop systems - Abstract
This paper investigates the problem of resilient fault-tolerant control for a class of Takagi–Sugeno fuzzy model which is described by fractional order differential equations. In particular, the system input under consideration is subject to actuator saturations, actuator faults, and nonlinearities. The main purpose of this paper is to put forward a generalized nonlinear resilient fault-tolerant controller that can make the considered system robustly asymptotically stable. Utilizing the concept of continuous frequency distribution, a new set of linear matrix inequalities, which are the sufficient conditions for robust asymptotic stability of the closed-loop system, are derived by using the indirect Lyapunov approach. Two numerical examples are included to illustrate the feasibility and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
17. Robust Simultaneous Fault Estimation and Nonfragile Output Feedback Fault-Tolerant Control for Markovian Jump Systems.
- Author
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Li, Xiaohang, Ahn, Choon Ki, Lu, Dunke, and Guo, Shenghui
- Subjects
ROBUST control ,STATE feedback (Feedback control systems) ,LINEAR matrix inequalities ,DESCRIPTOR systems ,CLOSED loop systems ,SYMMETRIC matrices - Abstract
This paper is devoted to solve the problems on simultaneous actuator and sensor fault estimations as well as the nonfragile fault-tolerant control (FTC) for a kind of Markovian jump systems with faults and disturbances. First, the considered system is converted to an augmented system by putting the sensor fault into the new state. Then, an adaptive observer is designed for the descriptor system with the actuator fault adjusted by the designed adaptive law. Based on the estimated actuator faults, an output-feedback-based FTC strategy is proposed to stabilize the closed-loop system against actuator and sensor faults, and disturbances, while showing robustness for the control gain perturbations. Sufficient conditions for the existences of the observer and controller are provided in forms of linear matrix inequalities. Finally, a practical application is given to express the validation and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
18. Asynchronous Event-Triggered Sliding Mode Control for Semi-Markov Jump Systems Within a Finite-Time Interval.
- Author
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Wang, Jing, Ru, Tingting, Xia, Jianwei, Shen, Hao, and Sreeram, Victor
- Subjects
DATA transmission systems ,SLIDING mode control ,TUNNEL diodes ,CLOSED loop systems ,LYAPUNOV functions ,ACTUATORS - Abstract
In this paper, the finite-time sliding mode control issue is studied for a series of semi-Markov jump systems subject to actuator faults, where an asynchronous control method is adopted to overcome the non-synchronous phenomenon between the system mode and controller mode. Additionally, the event-triggered protocol, which determines whether the transmission of data should be performed according to the threshold condition, is introduced to alleviate the burden of data transmission in the communication channel. This paper aims to devise an asynchronous event-triggered sliding mode control law so as to guarantee the trajectories of the resulting closed-loop system can be forced onto the predefined sliding surface in a finite-time interval. Thence, by means of the mode-dependent Lyapunov functions and the finite-time theory, sufficient conditions are derived to assure that the closed-loop system is mean-square finite-time bounded in both reaching and sliding motion phases. Eventually, a numerical example and a tunnel diode circuit model are presented to illustrate the availability and practicability of the proposed approach. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
19. Robust Feedback-Linearizing Output Voltage Regulator for DC/DC Boost Converter.
- Author
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Kim, Seok-Kyoon and Lee, Kyo-Beum
- Subjects
VOLTAGE regulators ,DC-to-DC converters ,PARAMETER estimation ,CLOSED loop systems ,FEEDBACK control systems ,ROBUST control - Abstract
This paper suggests a cascade output voltage regulation strategy for dc/dc boost converters that embeds a robust inner-loop current controller against parameter variations. The contributions of this paper are divided into two parts. The first contribution is to present a simple and robust inner-loop current controller despite parameter uncertainties, guaranteeing the stability of the whole closed-loop system including the first-order internal dynamics. The second contribution is to show that an outer-loop proportional–integral regulator can stabilize the output voltage error without relying on any parameter information. Simulations and experiments using a 3-kW dc/dc boost converter showed that the proposed method offers satisfactory closed-loop performance in the presence of parameter uncertainties. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
20. Hybrid PD-Fuzzy and PD Controllers for Trajectory Tracking of a Quadrotor Unmanned Aerial Vehicle: Autopilot Designs and Real-Time Flight Tests.
- Author
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Santoso, Fendy, Garratt, Matthew A., and Anavatti, Sreenatha G.
- Subjects
FLIGHT testing ,CLOSED loop systems ,ROBUST control ,AUTOMATIC pilot (Airplanes) ,TRACKING control systems ,VERTICALLY rising aircraft ,HYBRID systems ,AERODYNAMICS of buildings - Abstract
This paper presents a hybrid nonlinear control system, comprising of a conventional proportional-differential (PD) controller and a PD-type fuzzy logic autopilot for the trajectory tracking of a quadcopter drone. Given the inherent nature of traditional control, which is model-based, and the essence of fuzzy logic control, which is knowledge-based, the proposed hybrid controllers can provide a more robust solution in the face of uncertainties. Both controllers operate in a parallel incremental form to improve the transient performance and the robustness of the closed-loop control system. Through extensive computer simulations supported by real-time flight tests, this paper highlights the efficacy of the proposed hybrid control system in the presence of some parameter variations, nonlinear aerodynamic models, and some external disturbances (e.g., wind gusts). The Dryden and 1–cos turbulence models are employed to represent the effects of wind gusts under realistic flight environments. The stability analysis of the closed-loop control system is conducted using Lyapunov’s indirect method. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
21. Nonlinearity Estimator-Based Control of A Class of Uncertain Nonlinear Systems.
- Author
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Yang, Jun, Li, Ting, Liu, Cunjia, Li, Shihua, and Chen, Wen-Hua
- Subjects
NONLINEAR systems ,UNCERTAIN systems ,ROBUST control ,TRACKING control systems ,CLOSED loop systems ,LYAPUNOV functions ,NONLINEAR equations ,UNCERTAINTY - Abstract
The robust control problem of a class of nonlinear systems subject to external disturbances, control gain uncertainty, and nonlinear uncertainties is investigated in this paper using a nonlinearity estimator-based control approach. Different from the existing results, the crucial but highly restrictive hypothesis on the boundedness of nonlinear uncertainties is removed from this paper by means of the tools of semiglobal stabilization. By delicately constructing a specific composite Lyapunov function for the closed-loop system as well as several useful level sets, the rigorous qualitative robustness performance is presented for the closed-loop system. Finally, an example of a single-link manipulator is utilized to demonstrate the performance specification claimed by the theoretical analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
22. Distributed Control of DC Grids: Integrating Prosumers’ Motives.
- Author
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Cucuzzella, M., Bouman, T., Kosaraju, K. C., Schuitema, G., Lemmen, N. H., Johnson-Zawadzki, S., Fischione, C., Steg, L., and Scherpen, J. M. A.
- Subjects
SMART power grids ,MICROGRIDS ,TRANSMISSION line matrix methods ,CLOSED loop systems - Abstract
In this paper, a novel distributed control strategy addressing a (feasible) psycho-social-physical welfare problem in islanded Direct Current (DC) smart grids is proposed. Firstly, we formulate a (convex) optimization problem that allows prosumers to share current with each other, taking into account the technical and physical aspects and constraints of the grid (e.g., stability, safety), as well as psycho-social factors (i.e., prosumers’ personal values). Secondly, we design a controller whose (unforced) dynamics represent the continuous time primal-dual dynamics of the considered optimization problem. Thirdly, a passive interconnection between the physical grid and the controller is presented. Global asymptotic convergence of the closed-loop system to the desired steady-state is proved and simulations based on collected data on psycho-social aspects illustrate and confirm the theoretical results. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
23. Self-Tuning PLL: A New, Easy, Fast and Highly Efficient Phase-Locked Loop Algorithm.
- Author
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Sanchez-Herrera, Reyes, Andujar, Jose M., Marquez, Marco, Mejias, Andres, and Gomez-Ruiz, Gabriel
- Subjects
PHASE-locked loops ,CLOSED loop systems ,ELECTRIC filters ,ELECTRONIC circuits - Abstract
A phase-locked loop or phase lock loop (PLL) is, essentially, a closed loop control system, where its output signal (regulated) maintains a direct (chosen) relationship to the input signal (unregulated). If the phases of the input and output signals remain the same, their frequencies will also match. In its usual way, a PLL is an electronic circuit with filters and controllers that must be tuned each time, according to the input signal parameters. As a contribution and novelty, this paper introduces a new, easy, fast and highly efficient PLL algorithm, that it does not need to adjust every time the input signal changes. This makes it independent of the input signal it receives and, therefore, and in a certain way, universally applicable. In addition, the proposal is implemented exclusively by software, housed in a microcontroller, which also represents another novelty. As another remarkable feature, the proposed algorithm is very simple, with a very low computational cost, which makes it very stable, practically insensitive to noise, and very fast. These characteristics and the performance shown over a wide range of input signal frequencies, make the proposed algorithm suitable for use in different applications, from the electricity grid synchronization to the demodulation of frequency modulation, DC motor drives, etc. In addition to frequency and phase tracking, the developed algorithm generates the signal corresponding to the fundamental frequency of the input signal. Furthermore, the algorithm behavior is not affected by the input signal distortion and is independent of its initial phase. The performance and excellent behavior of the developed algorithm are evaluated through simulations and experimental tests. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
24. Transportation Control of Double-Pendulum Cranes With a Nonlinear Quasi-PID Scheme: Design and Experiments.
- Author
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Sun, Ning, Yang, Tong, Fang, Yongchun, Wu, Yiming, and Chen, He
- Subjects
EXPERIMENTAL design ,CRANES (Machinery) ,CLOSED loop systems ,NONLINEAR dynamical systems ,NONLINEAR equations ,CAUSATION (Philosophy) ,PID controllers - Abstract
In real-world applications, industrial cranes commonly suffer from effects caused by the so-called double-pendulum phenomenon in many situations. However, at present, the double-pendulum phenomenon is usually directly roughly neglected when designing control methods. For double-pendulum cranes, most currently available approaches are open loop control; the existing feedback methods are mostly developed based on linearized dynamic models (around the equilibrium point) or designed without adding integral terms in the control laws, which may cause positioning errors in the presence of unmodeled dynamics. To address these problems, this paper proposes a new quasi-proportional integral derivative control method to effectively control underactuated double-pendulum crane systems. Then, we provide rigorous theoretical analysis for the equilibrium point of the closed-loop system based on the original nonlinear dynamic equations. To our knowledge, this paper gives the first plant-parameter-free controller that incorporates both integral action and actuating constraints without any linearizing operations during controller design or closed-loop analysis, which theoretically ensures that the controller can work well in the presence of unmodeled dynamics (e.g., insufficient friction compensation), actuating constraints, and large swing angles (i.e., not satisfying linearization conditions). Finally, hardware experimental results are provided to examine the effectiveness of the suggested control method. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
25. An Increased Nonlinear Coupling Motion Controller for Underactuated Multi-TORA Systems: Theoretical Design and Hardware Experimentation.
- Author
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Wu, Yiming, Sun, Ning, Fang, Yongchun, and Liang, Dingkun
- Subjects
MOTION control devices ,ENERGY function ,UNCERTAINTY (Information theory) ,HARDWARE ,ACTUATORS ,CLOSED loop systems ,MECHANICAL engineering - Abstract
In mechanical engineering, multi-translational oscillator with rotational actuator (multi-TORA) systems have been introduced to study the self-synchronized phenomenon as well as to investigate the vibration damping problem associated with many vibrational mechatronic systems, e.g., hand-held drills. Due to the lack of available actuators, multi-TORA systems are typically underactuated. Multi-TORA systems consist of a series of single TORA subsystems connected to and coupled with each other by elastic springs. For practical multi-TORA systems, the plant parameters are usually unknown or difficult to measure. Moreover, they exhibit strong nonlinear coupling behaviors. These factors bring much difficulty for both controller design and analysis. The control problem for underactuated multi-TORA systems with parametric uncertainties is challenging and still open. To address the above issues, this paper proposes a nonlinear increased motion control scheme for multi-TORA systems with parametric uncertainties. Specifically, a novel energy function is constructed and some extra coupling terms are introduced into the proposed controller for improving the transient performance. Then, based on Lyapunov techniques, we rigorously prove the asymptotic stability for the equilibrium point of the closed-loop system. As far as we know, this paper gives the first smooth control law to yield global asymptotic control results for underactuated multi-TORA systems suffering from unknown/uncertain plant parameters. To verify the effectiveness of the proposed controller, a series of hardware experiments are carried out on a self-built double-TORA hardware testbed, which indicate that the controller achieves effective control results in various conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
26. Fuzzy Reduced-Order Compensator-Based Stabilization for Interconnected Descriptor Systems via Integral Sliding Modes.
- Author
-
Li, Jinghao and Zhang, Qingling
- Subjects
DESCRIPTOR systems ,SLIDING mode control ,CLOSED loop systems ,DYNAMICAL systems - Abstract
This paper investigates the integral sliding mode control problem of T–S fuzzy interconnected descriptor system based on a reduced-order compensator. A canonical equivalent form for T–S fuzzy interconnected descriptor system is first introduced to facilitate the reduced-order compensator design. In terms of the measurable output variables of the T–S fuzzy interconnected descriptor system and the state variables of the proposed reduced-order compensator, an integral sliding mode control scheme is then developed for the T–S fuzzy interconnected descriptor system. The sliding motion is defined in the augmented space formed by the state variables of the original T–S fuzzy interconnected descriptor system and the resulting error system. It is shown that the designing parameters in the switching function can be simultaneously solved and the original T–S fuzzy interconnected descriptor system has no requirement to be relative degree one. Since the estimate error is bounded by an auxiliary dynamical system, when ideal sliding mode occurs, the resulting closed-loop system is asymptotically stable rather than uniformly ultimately bounded. Finally, a double-inverted pendulum system and a ball and beam system are numerically simulated to demonstrate the effectiveness and merits of the method proposed. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
27. The Predictive Closed-Loop Averaging Control of MMC Phase-Unit Losses Under Unbalanced Conditions.
- Author
-
Xu, Jianzhong, Yu, Yongjie, and Zhao, Chengyong
- Subjects
ELECTRIC potential ,ELECTRIC current converters ,CLOSED loop systems ,PHASE-locked loops ,ELECTRIC power systems - Abstract
This paper introduces an averaging control strategy of the phase-unit losses of modular multilevel converters (MMCs). The quantitative analysis of the MMC phase-unit loss distribution under unbalanced ac conditions is carried out by investigating the individual component of the MMC arm currents. It shows that the unbalanced arm currents will result in unbalanced phase-unit losses. To address this issue, this paper proposes a predictive closed-loop-control-based zero-sequence voltage injection method that results in much averaged loss distribution under unbalanced ac conditions. The essence of the new method is that it adjusts the three-phase sinusoidal references so that the unbalanced arm currents are fully utilized to average phase-unit losses. This paper shows the effectiveness of the new approach by electromagnetic transient simulations on PSCAD/EMTDC. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
28. Composite Velocity-Tracking Control for Flexible Gimbal System With Multi-Frequency-Band Disturbances.
- Author
-
Cui, Yangyang, Yang, Yongjian, Zhu, Yukai, Qiao, Jianzhong, and Guo, Lei
- Subjects
CLOSED loop systems ,LYAPUNOV stability ,SPACE vehicles ,FRICTION - Abstract
In this paper, a composite velocity-tracking control scheme is presented for improving dynamics response and control accuracy of the flexible gimbal system in the control moment gyro (CMG). Specifically, an ${H}_{\infty } $ optimal vibration controller (HOVC) is developed to weigh multi-performance of the gimbal system, such as stability, fast-tracking performance, and attenuation ability of multi-frequency-band disturbances. Meanwhile, a robust disturbance observer (RDO) designed on optimization technology is utilized to improve the nonlinear friction rejection ability of the gimbal system. Moreover, rigorous theoretical analysis based on the small-gain theory is provided to demonstrate the stability of the closed-loop gimbal system under multiple disturbances. Finally, experimental studies are presented to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
29. Adaptive Neural Tracking Control Scheme of Switched Stochastic Nonlinear Pure-Feedback Nonlower Triangular Systems.
- Author
-
Niu, Ben, Duan, Peiyong, Li, Junqing, and Li, Xiaodi
- Subjects
RADIAL basis functions ,SEPARATION of variables ,PSYCHOLOGICAL feedback ,NONLINEAR systems ,COORDINATE transformations ,CLOSED loop systems ,ARTIFICIAL satellite tracking - Abstract
In this paper, we address the adaptive neural tracking control problem for a class of uncertain switched stochastic nonlinear pure-feedback systems with nonlower triangular form. The significant design difficulty is the completely unknown nonlinear functions with all state variables that can neither be directly estimated by radial basis function (RBF) neural networks (NNs) nor be eliminated by the traditional backstepping technique. To achieve the control objective of this paper, a common state-feedback controller for all subsystems is first systematically constructed by using the common coordinate transformation, the variable separation technique, and the universal approximation capability of RBF NNs. Then the stability analysis shows that the semi-global bounded in probability of the whole closed-loop switched system can be obtained and the desired tracking performance can also be insured under a class of switching signals with the average dwell time property. Finally, simulation results are given to demonstrate the effectiveness of the obtained control scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
30. Stabilization of Networked Control Systems With Hybrid-Driven Mechanism and Probabilistic Cyber Attacks.
- Author
-
Liu, Jinliang, Wu, Zheng-Guang, Yue, Dong, and Park, Ju H.
- Subjects
CYBERTERRORISM ,STABILITY criterion ,STOCHASTIC analysis ,STABILITY theory ,LYAPUNOV stability ,CLOSED loop systems - Abstract
This paper investigates the controller design problem of networked control systems subject to cyber attacks. A hybrid-triggering communication strategy is employed to save the limited communication resources. State measurements are transmitted over a communication network and may be corrupted by cyber attacks. The aim of this paper is to design a controller for a new closed-loop system model with consideration of randomly occurring cyber attacks and the hybrid-triggering scheme. A stability criterion is obtained for the system stabilization by employing Lyapunov stability theory and stochastic analysis techniques. Moreover, the desired controller gain is derived by resorting to some matrix inequalities. Finally, a numerical example is exploited to demonstrate the usefulness of the proposed scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
31. Stability Analysis for Input Saturated Discrete-Time Switched Systems With Average Dwell-Time.
- Author
-
Wang, Qian, Yu, Haoyong, Wu, Zheng-Guang, and Chen, Guoda
- Subjects
DISCRETE-time systems ,EXPONENTIAL stability ,CLOSED loop systems ,RICCATI equation ,ACTUATORS ,STATE feedback (Feedback control systems) - Abstract
This paper studies the stability analysis of the input saturated discrete-time switched systems with average dwell-time based on the parametric discrete-time Riccati equation. The state feedback controller and the observer-based output feedback controller are designed to guarantee the exponential stability of the closed-loop system. The proposed method is simple and easy to operate in practice. The designed controllers can be computed easily by solving the parametric discrete-time Lyapunov equation. The main advantages of this paper are that the stability analysis is based on the properties of the saturation function and limited structure information of the actuator saturation and that the designed controllers have good robustness to the structure uncertainty of the input saturation. The simulation results illustrate the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
32. Stabilization for a General Class of Fractional-Order Systems: A Sampled-Data Control Method.
- Author
-
Li, Xinyao, Wen, Changyun, Li, Xiaolei, and Deng, Chao
- Subjects
DISCRETE-time systems ,CLOSED loop systems ,ADAPTIVE control systems ,EXPONENTIATION - Abstract
In this paper, based on sampled-data control method, we address the stabilization problem for a general class of linear continuous-time fractional systems whose solution contains the Mittag-Leffler function that does not obey the basic exponentiation identity. By considering the infinite memory and hereditary characteristics of fractional-order calculus, we propose a sampled-data controller that guarantees the resulting closed-loop system to be asymptotically stable. Simulation examples are presented to demonstrate the effectiveness of the proposed controller and verify the established results. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
33. Event-Triggered Adaptive Fault-Tolerant Control for a Class of Nonlinear Multiagent Systems With Sensor and Actuator Faults.
- Author
-
Wang, Xin, Zhou, Yuhao, Huang, Tingwen, and Chakrabarti, Prasun
- Subjects
FAULT-tolerant control systems ,MULTIAGENT systems ,NONLINEAR systems ,ACTUATORS ,CLOSED loop systems - Abstract
This paper investigates the leader-following consensus control problem for a class of nonlinear multiagent systems subject to sensor and actuator faults under a fixed directed graph. First, a fault compensation mechanism is proposed because of multiple faults wherein the adaptive parameters substitute the fault coefficients. Then, the command filtering method is employed to avoid the burst of complexity rendered by the duplicative differentiation of the virtual control signal. Furthermore, the neural networks-based state observers are designed to reconstruct the unmeasurable states of the nonlinear multiagent systems. According to the given design approach, a switching threshold-based event-triggered adaptive fault-tolerant control strategy is developed and ensures all the signals in the closed-loop system are semiglobally uniformly ultimately bounded (SGUUB). Finally, the simulation result is provided to demonstrate the validity of the presented method. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
34. A Blow-Up Function Approach to Global Event-Triggered Prescribed Tracking Output Feedback Control of Nonlinear Systems.
- Author
-
Ning, Pengju, Hua, Changchun, Li, Kuo, and Meng, Rui
- Subjects
ADAPTIVE control systems ,FEEDBACK control systems ,UNCERTAIN systems ,ADAPTIVE fuzzy control ,NONLINEAR systems ,CLOSED loop systems ,NONLINEAR dynamical systems - Abstract
In this paper, global event-triggered adaptive prescribed tracking output feedback control is investigated for a class of nonlinear uncertain systems with unknown control direction. Different from the existing works, the design of the tracking error-dependent normalized function and prescribed boundary is based on our uniformly defined blow-up function rather than a specific function, and the asymmetric constraint requirements on tracking error can be achieved by appropriately selecting the blow-up function. By utilizing the Kalman filter ($K$ -filter) and dynamic gain technique, a new reduce-order observer is proposed, which can make the estimated error exponentially converge to zero. In addition, by introducing a dynamic signal into the trigger condition, a novel event-triggered mechanism is proposed, which can extend the trigger time interval and completely counteract the event-triggered errors in terms of asymptotic stability by sacrificing part of the system transient performance. Furthermore, an adaptive controller is designed based on the backstepping method, which ensures the boundedness of the state of the closed-loop system, while regulating the tracking error meets the global prescribed performance requirements and approaches to zero asymptotically. Two examples are given to illustrate the effectiveness of the proposed control scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
35. Prescribed-Time Input-to-State Stabilization of Normal Nonlinear Systems by Bounded Time-Varying Feedback.
- Author
-
Zhang, Kang-Kang, Zhou, Bin, and Duan, Guang-Ren
- Subjects
NONLINEAR systems ,TIME-varying systems ,PARAMETRIC equations ,CLOSED loop systems ,PSYCHOLOGICAL feedback ,NONLINEAR equations - Abstract
This paper studies the prescribed-time input-to-state stabilization problem of normal nonlinear systems. With the help of some key properties of a class of parametric Lyapunov equations, the prescribed-time input-to-state stabilization problem of normal nonlinear systems under matched uncertainties is studied. Some bounded time-varying controllers are proposed. It is shown that the closed-loop systems are prescribed-time input-to-state stable. Finally, the effectiveness of the established methods is illustrated by two physical systems. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
36. Dynamic Event-Triggered Terminal Sliding Mode Control Under Binary Encoding: Analysis and Experimental Validation.
- Author
-
Song, Jun, Wang, Yu-Kun, and Niu, Yugang
- Subjects
SLIDING mode control ,PERMANENT magnet motors ,SPEED limits ,ENCODING ,CLOSED loop systems ,ADAPTIVE control systems - Abstract
This paper designs a novel nonsingular terminal sliding mode control (TSMC) scheme for a class of nonlinear systems under binary encoding transmission. To further ease the communication overheads between the plant and the controller, a dynamic event-triggered mechanism is also introduced to the TSMC design. Sufficient conditions are proposed, respectively, for guaranteeing the reachability to a practical sliding mode and the ultimate boundedness of the closed-loop system, in which the effects from the binary encoding and the dynamic event-triggered protocol are quantified clearly. The Zeno phenomena for the developed dynamic event-triggered mechanism is excluded via an explicit analysis. Finally, the feasibility and effectiveness of the proposed scheme are demonstrated by a numerical example and a real experiment on permanent magnet synchronous motor speed regulation system. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
37. Distributed Optimal Tracking Control of Discrete-Time Multiagent Systems via Event-Triggered Reinforcement Learning.
- Author
-
Peng, Zhinan, Luo, Rui, Hu, Jiangping, Shi, Kaibo, and Ghosh, Bijoy Kumar
- Subjects
DISCRETE-time systems ,REINFORCEMENT learning ,MULTIAGENT systems ,ITERATIVE learning control ,CLOSED loop systems - Abstract
In this paper, an event-triggered optimal tracking control of discrete-time multi-agent systems is addressed by using reinforcement learning. In contrast to traditional reinforcement learning-based methods for optimal coordination and control of multi-agent systems with a time-triggered control mechanism, an event-triggered mechanism is proposed to update the controller only when the designed events are triggered, which reduces the computational burden and transmission load. The stability analysis of the closed-loop multi-agent systems with event-triggered controller is described. Further, to implement the proposed scheme, an actor-critic neural network learning structure is proposed to approximate performance indices and to on-line learn the event-triggered optimal control. During the training process, event-triggered weight tuning law has been designed, wherein the weight parameters of the actor neural networks are adjusted only during triggering instances compared with traditional methods with fixed updating periods. Further, a convergence analysis of the actor-critic neural network is provided via Lyapunov method. Finally, two simulation examples show the effectiveness and performance of the obtained event-triggered reinforcement learning controller. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
38. Event-Triggered Mechanism for Multiple Frequency Services of Electric Vehicles in Smart Grids.
- Author
-
Pham, Thanh Ngoc, Oo, Amanullah Maung Than, and Trinh, Hieu
- Subjects
LINEAR matrix inequalities ,ELECTRIC vehicles ,JENSEN'S inequality ,LYAPUNOV stability ,CLOSED loop systems ,THEMATIC mapper satellite - Abstract
This paper considers an event-triggered mechanism (ETM) for multiple frequency services of electric vehicles (EVs) in smart grids (SGs). A new model of a SG with an ETM and multiple agents of EVs is introduced. ETM is deployed to reduce the load on network bandwidth. EVs are incorporated in both secondary and primary frequency services to suppress frequency fluctuations in the system. The behaviours of EV owners are also considered by using batteries SOC controls. Then, a mathematical model of the system is derived which contains parametric uncertainties due to the incorporation of SOC control, an ETM variable arising from ETM control, and a time-varying delay in both the state and control input vectors. We derive new Lyapunov stability and stabilizability conditions to ensure robust $H_{\infty }$ performance of the closed-loop system. The conditions are derived based on various mathematical tools including relaxed Jensen inequality, free weighting matrix technique, reciprocally convex approach, and matrix inequality for uncertainties. An effective procedure is proposed based on an approach using the state transformation and tractable linear matrix inequalities to synthesis robust static output feedback controller gains. Extensive simulations of a SG with three agents of EVs are undertaken to validate of our proposed control scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
39. Switching Adaptive Controller for the Nonlinear Systems With Uncertainties From Unknown Powers.
- Author
-
Wang, Meiqiao, Liu, Yungang, and Man, Yongchao
- Subjects
NONLINEAR systems ,UNCERTAIN systems ,CLOSED loop systems ,STATE feedback (Feedback control systems) ,PROGRAMMABLE controllers ,INTEGRATORS - Abstract
This paper considers the global stabilization for a class of uncertain nonlinear systems with unknown powers, unknown control directions, and unknown nonlinearities. Mainly due to the presence of the unknown powers which have not known upper bound, no existing methods are applicable to the control problem to be solved. In this paper, to compensate the serious system uncertainties and particularly to overcome the major obstruction from unknown powers, we appeal to the mechanism of switching adaptive feedback. By flexibly combining the domination and the method of adding a power integrator, we propose a new adaptive controller design, whose design parameters are tuned online based on a switching logic. The designed controller will become operative as long as finite switchings happen and will not lead to Zeno phenomenon, and can guarantee the global boundedness as well as ultimate convergence of the resulting closed-loop system. Two numerical examples are given to demonstrate the effectiveness of the developed design scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
40. Uncertainty and Disturbance Estimator-Based Control of a Flapping-Wing Aerial Vehicle With Unknown Backlash-Like Hysteresis.
- Author
-
Yin, Zhao, He, Wei, Kaynak, Okyay, Yang, Chenguang, Cheng, Long, and Wang, Yu
- Subjects
ROBUST control ,CLOSED loop systems ,UNCERTAINTY ,SYSTEM analysis ,HYSTERESIS ,VEHICLES - Abstract
Robust and accurate control of a flapping-wing aerial vehicle (FWAV) system is a challenging problem due to the existence of backlash-like hysteresis nonlinearity. This paper proposes uncertainty and disturbance estimator (UDE)-based control with output feedback for FWAV systems. The approach enables the acquisition of the approximate plant model with only a partial knowledge of system parameters. For the design of the controller, only the bandwidth information of the unknown plant model is needed, which is available through the UDE filter. The stability analysis of the closed-loop system with the UDE-based controller is presented. It is shown that the proposed control scheme can ensure the boundedness of the control signals. A number of numerical simulations are carried out to demonstrate the satisfactory trajectory tracking performance of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
41. Necessary and Sufficient Conditions for Leader-Following Bipartite Consensus With Measurement Noise.
- Author
-
Ma, Cui-Qin and Xie, Lihua
- Subjects
NOISE measurement ,MULTIAGENT systems ,SPANNING trees ,EIGENVALUES - Abstract
This paper considers leader-following bipartite consensus of single-integrator multiagent systems in the presence of measurement noise. To attenuate the noise, a time-varying consensus gain ${q}$ (${t}$) is introduced into the stochastic approximation-type protocol. Necessary and sufficient conditions for ensuring a strong mean square leader-following bipartite consensus are given. In particular, in the absence of measurement noise, the convergence speed of error dynamics is dependent on the eigenvalues of Laplacian and the rate of ${\int ^{{t}}_{0}{q}({s})\text {d}{s}}$ approaching infinity. By appropriately choosing ${q}$ (${t}$), the speed of leader-following bipartite consensus convergence can be improved in a fixed communication topology. It is proven that conditions for the signed digraph to be structurally balanced and having a spanning tree are necessary and sufficient to ensure leader-following bipartite consensus, regardless of measurement noise. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
42. Finite-Time H∞ Controller Synthesis of T–S Fuzzy Systems.
- Author
-
Li, Yue, Liu, Lu, and Feng, Gang
- Subjects
NONLINEAR control theory ,FUZZY systems ,LINEAR matrix inequalities ,LYAPUNOV functions ,CLOSED loop systems ,NONLINEAR systems ,ROBUST control - Abstract
This paper studies the finite-time H
∞ control problem of T–S fuzzy systems subject to external disturbances. A novel fuzzy control approach is developed on the basis of the control Lyapunov function technique and the finite-time Lyapunov theorem so that the closed-loop fuzzy system is finite-time stable with guaranteed H∞ performance. It is shown that the proposed control approach does not require the existence of a Lyapunov function before design of the fuzzy controller in comparison with many existing control approaches to finite-time control of nonlinear systems via the technique of control Lyapunov functions, and thus, the finite-time controller and the corresponding Lyapunov function can be designed simultaneously. The procedures on how to obtain the fuzzy controller are provided in terms of linear matrix inequalities. Moreover, an upper bound on the time taken for state trajectories to arrive at their desired targets is estimated. The effectiveness of the proposed finite-time H∞ control approach is finally illustrated via numerical simulations. [ABSTRACT FROM AUTHOR]- Published
- 2020
- Full Text
- View/download PDF
43. Simultaneous Input and State Estimation for Integrated Motor-Transmission Systems in a Controller Area Network Environment via an Adaptive Unscented Kalman Filter.
- Author
-
Jiang, Kai, Zhang, Hui, Karimi, Hamid Reza, Lin, Jing, and Song, Lingjun
- Subjects
KALMAN filtering ,TIME delay estimation ,AUTOMOBILE power trains ,FAULT diagnosis ,COVARIANCE matrices ,CLOSED loop systems ,ELECTRIC vehicles - Abstract
As the requirements on powertrain efficiency of electric vehicles (EVs) are increasing, integrated motor-transmission (IMT) powertrain systems for EVs are becoming a promising solution. For the integration of IMT powertrain systems, the system state information and the actuator status are usually required for the closed-loop controller design or the on-board fault diagnosis. Embracing the demands, an observer for simultaneous estimation of input and system state of an IMT powertrain system is studied in this paper. It is well-known that controller area network (CAN) has been dominant in the vehicle network, which is used to communicate among controllers, sensors, and actuators. However, the CAN bus always induces time-varying delays when there are a number of communication nodes on the bus. The CAN-bus induced delay would result in vibrations in the vehicle powertrain or even deterioration of the entire closed-loop system. To deal with the CAN-bus induced delay in the estimation work for IMT powertrain systems, the potential random delays are considered in a three-state nonlinear model which represents the behavior of an IMT system. To estimate the input and state simultaneously, an adaptive unscented Kalman filter (AUKF) is adopted. As we know, the adopted AUKF has the benefits of dealing with system nonlinearities and calculating the noise covariance matrix automatically. Simulations and comparisons are carried out. We can see from the results that the proposed observer estimates the input and system state well. Moreover, the resulting estimation error is smaller comparing with the estimation error of the observer based on extended Kalman filter algorithm. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
44. Framework for Analysis and Quantification of Wide-Area Control Resilience for Power Systems.
- Author
-
Marinovici, Laurentiu Dan and Chen, Hua
- Subjects
PHASOR measurement ,CLOSED loop systems ,CYBERTERRORISM - Abstract
Wide-area control helps damp the inter-area oscillations in modern power systems. However, compared to traditional local control, it is more vulnerable to cyber attacks due to its dependence on remote real-time-communicated measurements. In this paper, a formal mathematical framework for analyzing resilience of various wide-area controllers under adversarial scenarios is proposed. A novel resilience index based on the $\mathcal {H}_2$ norm of the post-attack closed-loop system is defined. Computation of such an index is, in general, challenging due to the combinatorial nature of the attack profiles and the bilinear nature of the problem. To address these difficulties, a gradient-based path-following-like solution is developed in this paper to solve a relaxed version of the original non-convex problem. Case studies on IEEE 39-bus system are performed to demonstrate the usage of the proposed framework. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
45. Nonfragile and Nonsynchronous Synthesis of Reachable Set for Bernoulli Switched Systems.
- Author
-
Che, Wei-Wei, Su, Hongye, Shi, Peng, and Wu, Zheng-Guang
- Subjects
CLOSED loop systems ,DESIGN techniques ,SYMMETRIC matrices ,COMPUTER simulation - Abstract
In this paper, the problems of nonfragile and nonsynchronous synthesis for Bernoulli switched systems are studied. The disturbances in the systems are assumed to have bounded peak in the sense of mean square. With the interval additive gain variations consideration, a nonfragile and nonsynchronous controller is designed subject to a nonsynchronous assumption that the switching signals of the system are not accurately gained for synthesis. A sufficient condition that is dependent on the known sojourn probabilities of switching signals is proposed to ascertain the reachable set of the closed-loop system, which is a hidden Bernoulli model, mean square contained in an ellipsoid-like set. Several nonfragile and nonsynchronous controllers are parameterized to guarantee the corresponding requirements to be satisfied for the closed-loop systems. The effectiveness and advantages of the proposed new design techniques are illustrated by a numerical simulation example. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
46. Realization of Exact Tracking Control for Nonlinear Systems via a Nonrecursive Dynamic Design.
- Author
-
Zhang, Chuanlin, Yang, Jun, Wen, Changyun, Wang, Lei, and Li, Shihua
- Subjects
TRACKING control systems ,POLE assignment ,CLOSED loop systems ,NONLINEAR systems ,LYAPUNOV functions ,TRACKING algorithms - Abstract
This paper investigates a novel nonrecursive tracking control law design for a class of nonlinear systems via dynamic output feedback. As the main contribution of this paper, a global nonrecursive tracking design procedure is first proposed to render a simple construction of a realizable output feedback control law, whose gain selections follow the conventional pole placement approach while the stability margin can be guaranteed via a sufficiently large scaling gain. By introducing a Lyapunov function which neglects the virtual controllers in essence, rigorous analysis is presented to ensure the global stability. In addition, finite-time and asymptotical tracking results can now be achieved within the same design framework whereas the tunable homogeneous degree plays as a key role. As another contribution, by proposing a saturated dynamic compensator, a less ambitious but practical control objective, namely semiglobal stability is achieved of the closed-loop system to relax the requirement of the restrictive growth conditions for global control design. Taking consideration of the case when system is subject to mismatched disturbances, a unified design and stability analysis framework shows that the practical tracking result can also be realized. A numerical example is provided to illustrate the effectiveness of the nonrecursive design and the simplicity of the proposed tracking control algorithm. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
47. A Data-Driven Realization of the Control-Performance-Oriented Process Monitoring System.
- Author
-
Luo, Hao, Yin, Shen, Liu, Tianyu, and Khan, Abdul Qayyum
- Subjects
CLOSED loop systems ,TRANSFER functions ,UNCERTAINTY (Information theory) ,TRANSFER matrix - Abstract
The stability margin is an important attribute for the robustness analysis of the closed loop in a control system design, which indicates the tolerant-ability of the closed-loop stability to system uncertainty (or fault). Seeking to develop an advanced data-driven monitoring and management framework for control performance (especially for robust stability) of the closed-loop system, this paper presents a study on the data-driven realization of the closed-loop stability margin, and its application to control-performance-oriented process monitoring. Specifically, without identifying the system parameters, a data-driven realization of the stability margin is first determined based on the identified multiplication operator of the closed-loop transfer function matrices using time-domain closed-loop measurements. Second, a control-performance-oriented process monitoring approach is proposed based on the determined data-driven realization of the stability margin. The contributions of this paper will bridge the gap between the model-based robustness analysis/design and the data-driven techniques for the future research. The main results of this paper are verified and demonstrated through the case studies on a dc motor benchmark system. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
48. Filter-Based Adaptive Vibration Control for Active Vehicle Suspensions With Electrohydraulic Actuators.
- Author
-
Sun, Weichao, Pan, Huihui, and Gao, Huijun
- Subjects
AUTOMATIC control systems ,CLOSED loop systems ,FEEDBACK control systems ,ELECTROHYDRAULIC effect ,ACTUATORS - Abstract
Vehicle suspension systems are important for significantly improving passenger comfort and handling characteristics. A well-designed suspension system can improve the entire performance of the automobile chassis. In this paper, an adaptive vibration control strategy is proposed for nonlinear uncertain suspension systems to stabilize both the vertical and pitch motions of the car and, thus, to contribute to ride comfort. Simultaneously, ride holding performance is preserved within allowable limits in the controller design. Moreover, differing from the existing results, in most of which the effect of actuator dynamic is neglected, this paper considers the electrohydraulic systems as actuators to supply active forces into suspension systems. Furthermore, to overcome the “exploration of terms” problem existing in standard backstepping, a filter-based adaptive control strategy is subsequently proposed. Finally, a design example is shown to illustrate the effectiveness of the proposed active controllers, where different road conditions are considered in order to reveal the closed-loop system performance in detail. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
49. Practical Active Disturbance Rejection Control: Bumpless Transfer, Rate Limitation, and Incremental Algorithm.
- Author
-
Herbst, Gernot
- Subjects
AUTOMATIC control equipment ,ELECTRONIC controllers ,DISCRETE-time systems ,POWER electronics ,INDUSTRIAL electronics ,MATHEMATICAL models - Abstract
Practical applications of controllers often impose further requirements on the implementation beyond the actual control performance, such as the ability to switch between manual and automatic control or between different control laws or controller parameter settings, known as bumpless transfer. Another common requirement is to limit the control signal in magnitude and/or rate. This paper examines and extends several discrete-time variants of active disturbance rejection control (ADRC), which is increasingly being applied especially in the field of power electronics and drives, in this regard. Detailed guidelines for practical ADRC implementations with these abilities are presented, and all features are being demonstrated with the help of simulation examples. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
50. Online Parameter Adjustment Method for Arm Voltage Estimation of the Modular Multilevel Converter.
- Author
-
Taffese, Abel A., de Jong, Erik, D'Arco, Salvatore, and Tedeschi, Elisabetta
- Subjects
ELECTRIC potential ,VOLTAGE control ,ARM ,ELECTRIC potential measurement ,CLOSED loop systems ,TIME delay systems - Abstract
The method used to calculate insertion indexes plays an important role in determining the overall performance of the modular multilevel converter. Direct voltage control, which is the simplest option, results in a large circulating current ripple because this modulation technique does not account for the arm voltage ripples. This led to the development of compensated modulation techniques that compensate for the arm voltage ripples thereby eliminating the circulating current ripple. There are two variants of compensated modulation—closed loop and open loop. The closed-loop version requires measurement of the arm voltages without distortion and delay, which is difficult to achieve in practice. The open-loop method overcomes this challenge by using estimated arm voltages. However, accurate knowledge of the system parameters is needed for effective removal of the circulating current ripples. This is a limitation because the parameters change with time and operating conditions. This paper presents a modified version of the open-loop method, which includes a scheme for correcting parameter errors online. The method estimates the parameters, arm capacitances, and time delay, by using feedback controllers acting on the circulating current ripples. Mathematical derivation of the method, together with its validation using simulation and experimental tests, is presented in detail. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
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