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Chaos detection and control in a typical power system

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Chinese Physics B 2013年第1期22卷 119-123页

作者： Hossein Gholizadeh Amir Hassannia Azita Azarfar faculty of electrical & robotic engineering Shahrood University of Technology

In this paper, a new chaotic system is introduced. The proposed system is a conventional power network that demonstrates a chaotic behavior under special operating conditions. Some features such as Lyapunov exponents and a strange attractor show the chaotic behavior of the system, which decreases the system performance. Two different controllers are proposed to control the chaotic system. The first one is a nonlinear conventional controller that is simple and easy to construct, but the second one is developed based on the finite time control theory and optimized for faster control. A MATLAB-based simulation verifies the results.

关键词： chaos detection chaos control finite time control theory synchronous generator

H_∞ Consensus Control of Discrete-Time Multi-Agent Systems Under Network Imperfections and External Disturbance

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IEEE/CAA Journal of Automatica Sinica 2019年第3期6卷 667-675页

作者： Arezou Elahi Alireza Alfi Hamidreza Modares IEEE the faculty of electrical and robotic engineering Shahrood University of Technology the Department of Mechanical engineering at Michigan State University

This paper presents a distributed control protocol for consensus control of multi-agent systems(MASs) under external disturbances and network imperfections, including communication delay and random packet dropout. To comply with the discrete nature of networked systems, in contrast to most of the existing work for MASs under network imperfections,the agents are modeled by discrete-time dynamics. The communication network is considered to be undirected, its delay is considered to be time-varying but bounded, and its packet dropout is modeled by a Bernoulli distributed white *** conditions in terms of linear matrix inequalities(LMIs)for asymptotic mean-square consensus stability are derived under network imperfections without considering external disturbances.A desired disturbance attenuation level in the presence of both external disturbances and network imperfections is also provided.A simulation example is given to verify the effectiveness of the proposed approach in coping with network imperfection and disturbances.

关键词： Consensus distributed control H∞ control packet dropout stability time delay

Phase synchronization and synchronization frequency of two-coupled van der Pol oscillators with delayed coupling

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Chinese Physics B 2013年第7期22卷 79-83页

作者： Hossein Gholizade-Narm Asad Azemi Morteza Khademi faculty of electrical Electronic & Robotic EngineeringShahrood University Technology College of engineering Penn State University faculty of engineering Ferdowsi University of Mashhad

In this paper, phase synchronization and the frequency of two synchronized van der Pol oscillators with delay coupling are studied. The dynamics of such a system are obtained using the describing function method, and the necessary conditions for phase synchronization are also achieved. Finding the vicinity of the synchronization frequency is the major advantage of the describing function method over other traditional methods. The equations obtained based on this method justify the phenomenon of the synchronization of coupled oscillators on a frequency either higher, between, or lower than the highest, in between, or lowest natural frequency of the aggregate oscillators. Several numerical examples simulate the different cases versus the various synchronization frequency delays.

关键词： van der Pol oscillator delay coupling phase synchronization synchronization frequency

Fatigue Strength Analysis of Dissimilar Aluminum Alloy TIG Welds

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Journal of Wuhan University of Technology(Materials Science) 2025年第1期 265-274页

作者：廖祥雲王瑞杰 LIU Guoshou ZHAO Pinglin faculty of Mechanical and electrical engineering Kunming University of Science and Technology faculty of Civil engineering and Mechanics Kunming University of Science and Technology

The constant amplitude loading fatigue tests were carried out on the 6061/7075 aluminum alloy TIG fillet welded lap specimens in this study,and the weld seam cross-section hardness was *** experimental results show that most specimens mainly failed at the 7075 side weld toes even though the base material tensile strength of 7075 is higher than that of *** maximum stress-strain concentration in the two finite element models is located at the 7075 side weld toe,which is basically consistent with the actual fracture *** weld zone on the 7075 side experiences severe material softening,with a large ***,the Vickers hardness value on the 6061 side negligibly changes and fluctuates around 70 *** obvious defects are found on the fatigue fracture,but a large number of secondary cracks *** germinate from the weld toe and propagate in the direction of the plate *** reinforcement has a serious impact on fatigue *** life will decrease exponentially as the weld reinforcement increases under low *** is found that the notch stress method can give a better fatigue life prediction for TIG weldments,and the errors of the predicted results are within the range of two factors,while the prediction accuracy decreases under low *** equivalent structural stress method can also be used for fatigue life prediction of TIG weldments,but the errors of prediction results are within the range of three factors,and the accuracy decreases under high stress.

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Optimal Predictive Impedance Control in the Presence of Uncertainty for a Lower Limb Rehabilitation Robot

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Journal of Systems Science & Complexity 2020年第5期33卷 1310-1329页

作者： JALAEIAN-F.Mohsen FATEH Mohammad Mehdi RAHIMIYAN Morteza Department of electrical and robotic engineering Shahrood University of TechnologyShahroodIran

As an innovative concept,an optimal predictive impedance controlle is introduced here to control a lower limb rehabilitation robo in the presence of *** desired impedance law is considered to propose a conventional model-based impedance controller for the ***,external disturbances,model imperfection,and parameters uncertainties reduce the performance of the controller in *** order to cope with these uncertainties,an optimal predictive compensator is introduced as a solution for a proposed convex optimization problem,which is performed on a forward finite-length *** a result,the LLRR has the desired behavior even in an uncertain *** performance and efficiency of the proposed controller are verified by the simulation results.

关键词： Impedance control lower limb rehabilitation robots model predictive compensator optimal predictive impedance controller optimization in the presence of uncertainty

A Precise Robust Fuzzy Control of Robots Using Voltage Control Strategy

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International Journal of Automation and computing 2013年第1期10卷 64-72页

作者： Mohammad Mehdi Fateh Sara Fateh Department of electrical and robotic engineering Shahrood University of Technology

Fuzzy control of robot manipulators with a decentralized structure is facing a serious challenge. The state-space model of a robotic system including the robot manipulator and motors is in non-companion form, multivariable, highly nonlinear, and heavily coupled with a variable input gain matrix. Considering the problem, causes and solutions, we use voltage control strategy and convergence analysis to design a novel precise robust fuzzy control （PRFC） approach for electrically driven robot manipulators. The proposed fuzzy controller is Mamdani type and has a decentralized structure with guaranteed stability. In order to obtain a precise response, we regulate a fuzzy rule which governs the origin of the tracking space. The proposed design is verified by stability analysis. Simulations illustrate the superiority of the PRFC over a proprotional derivative like （PD-like） fuzzy controller applied on a selective compliant assembly robot arm （SCARA） driven by permanent magnet DC motors.

关键词： Precise performance fuzzy control robot manipulator voltage control strategy convergence analysis stability analysis

Modeling and Robust Discrete LQ Repetitive Control of electrically Driven Robots

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International Journal of Automation and computing 2013年第5期10卷 472-480页

作者： Mohammad Mehdi Fateh Maryam Baluchzadeh Department of electrical and robotic engineering Shahrood University of Technology

Discrete linear quadratic control has been efciently applied to linear systems as an optimal ***,a robotic system is highly nonlinear,heavily coupled and *** overcome the problem,the robotic system can be modeled as a linear discrete-time time-varying system in performing repetitive *** modeling motivates us to develop an optimal repetitive *** contribution of this paper is *** the frst time,it presents discrete linear quadratic repetitive control for electrically driven robots using the mentioned *** proposed control approach is based on the voltage control ***,uncertainty is efectively compensated by employing a robust time-delay *** uncertainty can include parametric uncertainty,unmodeled dynamics and external *** highlight its ability in overcoming the uncertainty,the dynamic equation of an articulated robot is introduced and used for the simulation,modeling and control *** analysis verifes the proposed control approach and simulation results show its efectiveness.

关键词： Discrete linear quadratic control repetitive control electrically driven robot robust time-delay controller uncertainty

Robust Control of robotic Manipulators in the Task-Space Using an Adaptive Observer Based on Chebyshev Polynomials

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Journal of Systems Science & Complexity 2020年第5期33卷 1360-1382页

作者： GHOLIPOUR Reza FATEH Mohammad Mehdi Department of electrical and robotic engineering Shahrood University of Technology*** ShahroodIran

In this paper,an adaptive observer for robust control of robotic manipulators is *** lumped uncertainty is estimated using Chebyshev ***,the uncertainty upper bound is required in designing observer-controller ***,obtaining this bound is a challenging *** solve this problem,many uncertainty estimation techniques have been proposed in the literature based on neuro-fuzzy *** an alternative,in this paper,Chebyshev polynomials have been applied to uncertainty estimation due to their simpler structure and less computational *** on strictly-positive-rea Lyapunov theory,the stability of the closed-loop system can be *** Chebyshev coefficients are tuned based on the adaptation rules obtained in the stability ***,to compensate the truncation error of the Chebyshev polynomials,a continuous robust control term is designed while in previous related works,usually a discontinuous term is *** SCARA manipulator actuated by permanent magnet DC motors is used for computer *** results reveal the superiority of the designed method.

关键词： Adaptive observer Chebyshev polynomials electrically driven robot manipulators robust control uncertainty estimation

具有适应性突变和惯性权重的粒子群优化(PSO)算法及其在动态系统参数估计中的应用(英文)

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自动化学报 2011年第5期37卷 541-549页

作者： ALFI Alireza faculty of electrical and robotic engineering

An important problem in engineering is the unknown parameters estimation in nonlinear *** this paper,a novel adaptive particle swarm optimization (APSO) method is proposed to solve this *** work considers two new aspects,namely an adaptive mutation mechanism and a dynamic inertia weight into the conventional particle swarm optimization (PSO) *** mechanisms are employed to enhance global search ability and to increase ***,three well-known benchmark functions namely Griewank,Rosenbrock and Rastrigrin are utilized to test the ability of a search algorithm for identifying the global *** performance of the proposed APSO is compared with advanced algorithms such as a nonlinearly decreasing weight PSO (NDWPSO) and a real-coded genetic algorithm (GA),in terms of parameter accuracy and convergence *** is confirmed that the proposed APSO is more successful than other aforementioned ***,the feasibility of this algorithm is demonstrated through estimating the parameters of two kinds of highly nonlinear systems as the case studies.

关键词：自动化 PSO APSO 线性系统