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Constrained tuning of two-parameter controllers: A centroid approach
, Article Proceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering ; Volume 226, Issue 5 , 2012 , Pages 685-698 ; 09596518 (ISSN) ; Tavazoei, M. S ; Sharif University of Technology
2012
Abstract
The problem of tuning a two-parameter controller has been formulated as finding the centroid of the admissible region specified by the set of constraints that the controller should satisfy. The constraints can be as general as the closed-loop system stability or they may include several requirements on various stability, sensitivity, or performance measures. The design of stabilizing proportional-derivative (PD) controllers using the centroid of the stability region in the controller parameter space is considered as a case study. To this end, analytical formulas are derived to describe the stability boundaries of a class of integrating time delay systems, the stability region of which has a...
Overshoot in the step response of fractional-order control systems
, Article Journal of Process Control ; Volume 22, Issue 1 , January , 2012 , Pages 90-94 ; 09591524 (ISSN) ; Sharif University of Technology
Abstract
In this paper, a sufficient condition for existence of an overshoot in the step response of fractional-order systems is presented. Based on this condition, it can be shown that the existence of an overshoot in the step responses of some classes of fractional-order systems (for example, the class of fractional-order systems having commensurate orders between 1 and 2) is unavoidable. To show the usefulness of the obtained condition, this condition is applied to prove some results on the time response analysis of fractional-order control systems
Observer-based adaptive fuzzy controller for nonlinear systems with unknown control directions and input saturation
, Article Fuzzy Sets and Systems ; May , 2016 ; 01650114 (ISSN) ; Shahrokhi, M ; Khajeh Talkhoncheh, M ; Sharif University of Technology
Elsevier
2016
Abstract
This paper addresses design of an observer-based adaptive fuzzy controller for a class of single-input-single-output (SISO) nonlinear systems with unknown dynamics subject to input nonlinearity and unknown direction. The proposed controller is singularity free. A high-gain observer is designed to estimate the unmeasured states, and the Lipschitz condition for proving boundedness of the estimated states is relaxed. The Nussbaum function is used to handle the unknown virtual control directions and the backstepping technique has been applied for controller design. It is proved that all closed loop signals are semi-globally uniformly ultimately bounded (SGUUB) and the output tracking error...
Model reference adaptive control in fractional order systems using discrete-time approximation methods
, Article Communications in Nonlinear Science and Numerical Simulation ; Volume 25, Issue 1-3 , August , 2015 , Pages 27-40 ; 10075704 (ISSN) ; Nojoumian, M. A ; Salarieh, H ; Meghdari, A ; Sharif University of Technology
Elsevier
2015
Abstract
In this paper, model reference control of a fractional order system has been discussed. In order to control the fractional order plant, discrete-time approximation methods have been applied. Plant and reference model are discretized by Grünwald-Letnikov definition of the fractional order derivative using "Short Memory Principle". Unknown parameters of the fractional order system are appeared in the discrete time approximate model as combinations of parameters of the main system. The discrete time MRAC via RLS identification is modified to estimate the parameters and control the fractional order plant. Numerical results show the effectiveness of the proposed method of model reference adaptive...
Experimental evaluation of pinned frame equipped with ribbed bracing system
, Article Journal of Earthquake Engineering ; 2017 , Pages 1-21 ; 13632469 (ISSN) ; Toufigh, V ; Golafshani, A. A ; Arzeytoon, A ; Sharif University of Technology
Abstract
This study presents the experimental investigation of half-scale, one-story, one-bay pinned frames equipped with a ribbed bracing system (RBS). The RBS is a newly developed passive control system designed to eliminate buckling and enhance the seismic behavior of structures. Here, mechanical models of this bracing system were designed and constructed. Pinned frames equipped with the RBS were cyclically tested. The hysteretic behavior and energy absorbing capacities of the frames were evaluated. Based on the results, the full plastic capacity of the brace was achieved and no buckling occurred. The RBS frame illustrated proper hysteretic behavior and energy dissipation capacity up to 4% story...
Hierarchical optimal control of large-scale nonlinear chemical processes
, Article ISA Transactions ; Volume 48, Issue 1 , January , 2009 , Pages 38-47 ; 00190578 (ISSN) ; Sadati, N ; Sharif University of Technology
2009
Abstract
In this paper, a new approach is presented for optimal control of large-scale chemical processes. In this approach, the chemical process is decomposed into smaller sub-systems at the first level, and a coordinator at the second level, for which a two-level hierarchical control strategy is designed. For this purpose, each sub-system in the first level can be solved separately, by using any conventional optimization algorithm. In the second level, the solutions obtained from the first level are coordinated using a new gradient-type strategy, which is updated by the error of the coordination vector. The proposed algorithm is used to solve the optimal control problem of a complex nonlinear...
Strong structural controllability of signed networks
, Article 58th IEEE Conference on Decision and Control, CDC 2019, 11 December 2019 through 13 December 2019 ; Volume 2019-December , 2019 , Pages 4557-4562 ; 07431546 (ISSN); 9781728113982 (ISBN) ; Haeri, M ; Mesbahi, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, we discuss the controllability of a family of linear time-invariant (LTI) networks defined on a signed graph. In this direction, we introduce the notion of positive and negative signed zero forcing sets for the controllability analysis of positive and negative eigenvalues of system matrices with the same sign pattern. A sufficient combinatorial condition that ensures the strong structural controllability of signed networks is then proposed. Moreover, an upper bound on the maximum multiplicity of positive and negative eigenvalues associated with a signed graph is provided. © 2019 IEEE
Experimental evaluation of pinned frame equipped with ribbed bracing system
, Article Journal of Earthquake Engineering ; Volume 23, Issue 8 , 2019 , Pages 1297-1317 ; 13632469 (ISSN) ; Toufigh, V ; Golafshani, A. A ; Arzeytoon, A ; Sharif University of Technology
Taylor and Francis Ltd
2019
Abstract
This study presents the experimental investigation of half-scale, one-story, one-bay pinned frames equipped with a ribbed bracing system (RBS). The RBS is a newly developed passive control system designed to eliminate buckling and enhance the seismic behavior of structures. Here, mechanical models of this bracing system were designed and constructed. Pinned frames equipped with the RBS were cyclically tested. The hysteretic behavior and energy absorbing capacities of the frames were evaluated. Based on the results, the full plastic capacity of the brace was achieved and no buckling occurred. The RBS frame illustrated proper hysteretic behavior and energy dissipation capacity up to 4% story...
Design of an H∞-optimal FOPID controller using particle swarm optimization
, Article 26th Chinese Control Conference, CCC 2007, Zhangjiajie, 26 July 2007 through 31 July 2007 ; October , 2007 , Pages 435-440 ; 7900719229 (ISBN); 9787900719225 (ISBN) ; Masoud, K. G ; Nasser, S ; Sharif University of Technology
2007
Abstract
This paper proposes a novel method to design an H∞-optimal Fractional Order PLD (FOPLD) controller with ability to control the transient, steady-state response and stability margins characteristics. The method uses particle swarm optimization algorithm and operates based on minimizing a general cost function. Minimization of the cost function is carried out subject to the H∞-norm; this norm is also included in the cost function to achieve its lower value. The method is applied to a phase-locked-loop motor speed system and an electromagnetic suspension system as two examples to illustrate the design procedure and verify performance of the proposed controller. The results show that the...
On tuning and complexity of an adaptive model predictive control scheduler
, Article Control Engineering Practice ; Volume 15, Issue 9 , 2007 , Pages 1169-1178 ; 09670661 (ISSN) ; Taheri, H ; Haeri, M ; Sharif University of Technology
2007
Abstract
In this paper, adaptive model predictive control is applied to schedule differentiated buffers in routers. The proposed algorithm, adaptive model predictive control scheduler (AMPCS), dynamically regulates the service rates of aggregated traffic classes. This algorithm guarantees some required constraints on proportional or absolute delay. The control parameters and the way they are adjusted as well as the problems of implementing the controller at high data rates are investigated. Theoretical analysis and numerical simulations demonstrate stability of AMPCS and its acceptable quality of service differentiations at core routers while maintaining end to end delay constraints. © 2007 Elsevier...
Control of the clad height in laser powder deposition process using a pid controller
, Article 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006, Chicago, IL, 5 November 2006 through 10 November 2006 ; 2006 ; 10716947 (ISSN); 0791837904 (ISBN); 9780791837900 (ISBN) ; Toyserkani, E ; Durali, M ; Khajepour, A ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2006
Abstract
Laser Powder Deposition (LPD) process is an advanced material processing technique which has many applications. Despite this fact, reliable and accurate control schemes have not yet fully developed for the process. In this paper, the problem of controlling the clad height in the LPD process is studied. Due to a faster response of the process to change in scanning velocity over the laser power, the scanning velocity is selected as the input control variable. Since the governing equations of the LPD process are complex for designing a controller, an identified nonlinear dynamic model is used. The model is a Hammerstein model with a linear dynamic and a nonlinear memoryless block. The model...
Design of a fuzzy controller for an underwater vehicle aiming at a stationary target
, Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) ; Sayyaadi, H ; Sharif University of Technology
American Society of Mechanical Engineers
2006
Abstract
In this paper, on the basis of a robust algorithm for the analysis of the 6 DOF motion of an underwater vehicle in calm water, after presenting the dynamics model and simulating motion, the model is put in the closed loop control to perform a controlled mission. The mission is defined as to navigate the submarine toward a desired point in the vertical plane. In performing the mission, the least time and of course the least position error with respect to the target point is aimed. The designed controller based on fuzzy logic and thus adapted to the human patterns for navigation, with a simple structure, performs the mission accurately. The intelligent structure of the fuzzy controller,...
Flight envelope expansion in landing phase using classic, intelligent, and adaptive controllers
, Article Journal of Aircraft ; Volume 43, Issue 1 , 2006 , Pages 91-101 ; 00218669 (ISSN) ; Izadi, H. A ; Pakmehr, M ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc
2006
Abstract
An expanding flight envelope in the landing phase of a typical jet transport aircraft in presence of strong wind shears using a learning capable control system (LCCS) is investigated. The idea stems from human beings functional architecture that gives them the ability to do more as they age and gain more experience. With the knowledge that classical controllers lack sufficient generality to cope with nonlinear as well as uncertain phenomenon such as turbulent air, the focuse is on different types of intelligent controllers due to their learning and nonlinear generalization capabilities as candidates for the landing flight phase. It is shown that the latter class of controllers could be used...
Development of a brake control system for a series hybrid electric city bus using fuzzy logic
, Article 2006 IEEE International Conference on Mechatronics and Automation, ICMA 2006, Luoyang, 25 June 2006 through 28 June 2006 ; Volume 2006 , 2006 , Pages 1345-1350 ; 1424404665 (ISBN); 9781424404667 (ISBN) ; Fazeli, A ; Valizadeh, M ; Sharif University of Technology
2006
Abstract
In this paper, a fuzzy based controller is developed in order to control the braking action of the rear axle of a series hybrid city bus. The controller's target is to recapture the kinetic energy of the bus as much as possible during braking, while still maintaining its stability. The bus under study Is one of the Iran-Khodro Company's productions called O457 which is currently undergoing a procedure of hybridization. The hybrid type used is a series hybrid configuration in which an internal combustion engine and a battery pack supply Its electric traction motors in order to propel the bus. The implemented fuzzy controller takes the bus speed, batteries SOC level and the brake-pedal...
Adaptive multi-model controller for robotic manipulators based on CMAC neural networks
, Article 2005 IEEE International Conference on Industrial Technology, ICIT 2005, Hong Kong, 14 December 2005 through 17 December 2005 ; Volume 2005 , 2005 , Pages 1012-1017 ; 0780394844 (ISBN); 9780780394841 (ISBN) ; Bagherpour, M ; Ghadami, R ; Sharif University of Technology
2005
Abstract
In this paper, an adaptive multi-model controller based on CMAC neural networks (AMNNC) is developed for uncertain nonlinear MIMO systems. AMNNC is a kind of adaptive feedback linearizing controller where nonlinearity terms are approximated with multiple neural networks. The weighted sum of the multiple neural networks is used to approximate the system nonlinearity for a given task. The proposed control scheme is applied to control a robotic manipulator, where some varying tasks are repeated but information on the load is not defined; it is unknown and varying. It is shown how the proposed controller is effective because of its capability to memorize the control skill for each task using...
Experimental investigation on the micro-step control disturbance rejection under random excitations
, Article DETC2005: ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Long Beach, CA, 24 September 2005 through 28 September 2005 ; Volume 1 B , 2005 , Pages 1747-1751 ; 0791847381 (ISBN) ; Behzad, M ; Sharif University of Technology
2005
Abstract
Effect of random signals with various powers, as current loads, on positioning and disturbance rejection problems on micro-step PID closed loop control system is addressed in this paper. Experimental results due to implementing different white noise power, speed, and a 0.3 N.m disturbance load torque show that, Random noise source changes current profile and affects the accuracy of positioning in tracking and disturbance rejection problems. Performance of the PID proposed controller under the implementation of random noise on phases of the HSM has been proved to be accurate enough even under disturbance torque acting on the system. Copyright © 2005 by ASME
Control of a nonlinear system using the saturation phenomenon
, Article Nonlinear Dynamics ; Volume 42, Issue 2 , 2005 , Pages 113-136 ; 0924090X (ISSN) ; Ghorashi, M ; Sharif University of Technology
2005
Abstract
In this paper, a theoretical investigation of nonlinear vibrations of a 2 degrees of freedom system when subjected to saturation is studied. The method has been especially applied to a system that consists of a DC motor with a nonlinear controller and a harmonic forcing voltage. Approximate solutions are sought using the method of multiple scales. It is shown that the closed-loop system exhibits different response regimes. The nature and stability of these regimes are studied and the stability boundaries are obtained. The effects of the initial conditions on the response of the system have also been investigated. Furthermore, the second-order solution is presented and the corresponding...
Application of extended DMC for nonlinear MIMO systems
, Article Computers and Chemical Engineering ; Volume 29, Issue 9 , 2005 , Pages 1867-1874 ; 00981354 (ISSN) ; Zadehmorshed Beik, H ; Sharif University of Technology
2005
Abstract
In this paper, an extended approach to the nonlinear DMC algorithm is proposed, which can handle constrained and MIMO systems under some defined conditions. This extension also admits higher control horizon, M and prediction horizon, P that are required to increase the performance of the controller in the most practical applications. Simulation results of the proposed method in the control of a stirred tank reactor with 2 inputs, 2 outputs nonlinear model and also a power unit nonlinear model with 3 inputs, 3 outputs are presented to illustrate effectiveness of the method and its justification. © 2005 Elsevier Ltd. All rights reserved
Nonlinear optimal control of large-scale systems; Part II - Interaction balance principle
, Article ICIECA 2005: International Conference on Industrial Electronics and Control Applications 2005, Quito, 29 November 2005 through 2 December 2005 ; Volume 2005 , 2005 ; 0780394194 (ISBN); 9780780394193 (ISBN) ; Marvast, E. D ; Sharif University of Technology
IEEE Computer Society
2005
Abstract
In this part, similar to Part I of this paper, a new two-level method for nonlinear optimal control of large scale systems is introduced. This approach is based on Interaction Balance Principle for coordination of large-scale systems. In the first level, the optimization problems are solved for nonlinear dynamics using a gradient method, and in the second level, the coordination is done using the gradient of errors to improve the convergence rate in compare to the classical Goal Coordination method and obtain the overall optimal solution. The efficacy and advantages of the new approach is shown in an application example. © 2005 IEEE
Output feedback adaptive decentralized control of cooperative robots
, Article ICIECA 2005: International Conference on Industrial Electronics and Control Applications 2005, Quito, 29 November 2005 through 2 December 2005 ; Volume 2005 , 2005 ; 0780394194 (ISBN); 9780780394193 (ISBN) ; Elhamifar, E ; Sharif University of Technology
IEEE Computer Society
2005
Abstract
In this paper a decentralized control scheme for multiple cooperative manipulators is developed to achieve the desired performance in motion and force tracking, in the presence of uncertainties in dynamic equations of the robots. To eliminate the effects of uncertainties in the closed-loop performance, a new adaptive control algorithm is proposed. Based on the Lyapunov stability method, it is proved that all the error signals in the closed-loop system which is compose of a robot, an observer and a controller asymptotically converge to zero. Also to avoid the difficulties of using velocity sensors within the cooperative system, an output feedback control scheme with a linear observer is used....