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control-systems
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Adaptive generalized predictive control of active queue management in TCP networks
, Article EUROCON 2005 - The International Conference on Computer as a Tool, Belgrade, 21 November 2005 through 24 November 2005 ; Volume I , 2005 , Pages 676-679 ; 142440049X (ISBN); 9781424400492 (ISBN) ; Haeri, M ; Sharif University of Technology
IEEE Computer Society
2005
Abstract
This paper develops methodology and technique tor the design, analysis, and impie mentation of an adaptive generalized predictive controller (AGPC) for Active Queue Management in TCP Networks. The TCP/AQM dynamic is modeled experimentally as a second-order system with a time delay where its parameters are estimated using the standard gradient algorithm. Based on this model, an AGPC is designed to gain the set-point tracking and robustness. AGPC, as a queue-based control mechanism, responds quickly to traffic changes, thus allowing for high utilization and small loss. We illustrate our results using ns-2 simulations and demonstrate the practical impact of adaptive model reference control on...
A two-level gradient based approach for intelligent coordination of large-scale systems - Part I
, Article ICTAI 2005: 17th IEEE International Conference on Tools with Artificial Intelligence, ICTAI'05, Hong Kong, 14 November 2005 through 16 November 2005 ; Volume 2005 , 2005 , Pages 470-477 ; 10823409 (ISSN); 0769524885 (ISBN); 9780769524887 (ISBN) ; Sharif University of Technology
IEEE Computer Society
2005
Abstract
In this paper, the concept of coordination is introduced within the framework of two-level large-scale systems and a new approach based on Interaction Prediction Principle is presented. The proposed approach is formulated in an intelligent manner in such a way that it provides a new strategy that can be used to synthesize an on-line supervisory controller for the overall two-level large-scale systems, extendable to multi-level control systems. By using the new methodology which is based on using neural network for modeling each sub-system, typical gradient method for optimization of first-level sub-problems, and the gradient of the interaction prediction errors related to the predicted...
A fast optimal flux search controller with improved steady state behavior for DTC based induction motor drives
, Article 2005 IEEE International Conference on Electric Machines and Drives, San Antonio, TX, 15 May 2005 through 15 May 2005 ; 2005 , Pages 1732-1736 ; 0780389875 (ISBN); 9780780389878 (ISBN) ; Vahdati Khajeh, E ; Zolghadri, M. R ; Homaifar, A ; Sharif University of Technology
IEEE Computer Society
2005
Abstract
Flux search controllers are proposed to improve the efficiency of electrical motors especially induction motors. In this paper, a flux search controller is proposed to increase the efficiency of a direct torque controlled induction motor with light load. The reference flux value is determined through a two stage minimization algorithm with the amplitude of the stator current as the objective function. In the transient state, a great flux step is used to speed up the convergence. In the steady state, a noise cancellation algorithm is used to let using small flux step and improves the steady state behavior of flux controller. Simulation and experimental confirm the fast dynamics of the...
Tracking control of an underwater vehicle using adaptive back-stepping with tuning function
, 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 4 , 2005 , Pages 131-138 ; 0791847411 (ISBN); 9780791847411 (ISBN) ; Saghafi, M. M ; Sharif University of Technology
American Society of Mechanical Engineers
2005
Abstract
In this article the design and simulation of a velocity and position control for an underwater Remotely Operated Vehicle (ROV) is addressed. The system has a nonlinear dynamic with parametric uncertainties making it a reasonable test-bed for investigating the effectiveness of robust nonlinear control algorithms. The studied ROV can be actively controlled along the 3 Cartesian coordinate directions and rotated about the vertical axis using 4 thrusters positioned on the ROV. The dynamics of the actuator system, consisting of thrusters, is assumed to be a first order linear system with an unknown parameter. To control this system adaptive back-stepping, as a robust adaptive nonlinear control...
Design and real-time experimental implementation of gain scheduling PID fuzzy controller for hybrid stepper motor in micro-step operation
, Article Proceedings of the IEEE International Conference on Mechatronics 2004, ICM'04, Istanbul, 3 June 2004 through 5 June 2004 ; 2004 , Pages 421-426 ; 0780385993 (ISBN) ; Alasty, A ; Sharif University of Technology
2004
Abstract
In this paper, design and real time experimental implementation of Fuzzy Gain Scheduling of PID controller for Hybrid Stepper Motor in Micro-stepping operation is described that was developed to track the desired positioning problem. The control problems characterized by mathematical models exhibit significant nonlinearity and uncertainty. Good performance of proposed Fuzzy PID controller are shown
Impact of Internally Heat-Integrated Distillation Column Configuration on Energy Saving
, M.Sc. Thesis Sharif University of Technology ; Pishvaie, Mahmoud Reza (Supervisor) ; Rashtchian, Davood (Supervisor)
Abstract
Distillation is the most widely-used but the most energy-consuming separation process in the chemical industry. The thermal energy added at the reboiler is used to evaporate a liquid mixture and is wasted when liquefying the vapor flow at the condenser to obtain a reflux liquid flow. However, the thermal energy recovered at the condenser cannot be used to heat other flows in the same distillation column since its temperature is lower than the other stages. To improve the low energy efficiency of distillation, various new ideas have been proposed in the literature. One of them is the internally heat-integrated distillation column (HIDiC). In a conventional distillation column, the temperature...
Chaos control in continuous mode of T-AFM systems using nonlinear delayed feedback via sliding mode control
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings ; Volume 11 PART A , 2008 , Pages 201-208 ; ISBN: 079184305X ; Salaried, H ; Alasty, A ; Sharif University of Technology
Abstract
The taping mode Atomic Force Microscopic (T-AFM) can be assumed as a cantilever beam which its base is excited by a sinusoidal force and nonlinear potential interaction with sample. Thus the cantilever may cause chaotic behavior which decreases the performance of the sample topography. In order to modeling, using the galerkin method, the PDE equation is reduced to a single ODE equation which properly describing the continuous beam. In this paper a nonlinear delayed feedback control.is proposed to control.chaos in T-AFM system. Assuming model parameters uncertainties, the first order Unstable Periodic Orbits (UPOs) of the system is stabilized using the sliding nonlinear delayed feedback...
Compensation by fractional-order phase-lead/lag compensators
, Article IET Control Theory and Applications ; Volume 8, Issue 5 , 2014 , Pages 319-329 ; ISSN: 17518644 ; Tavakoli Kakhki, M ; Sharif University of Technology
Abstract
This study deals with a generalised version of lead/lag compensators known as fractional-order lead/lag compensators. Exact and simple formulas are found for designing this introduced type of fractional-order compensators in order to provide the required magnitude and phase at a given frequency. Also, the region in the phase-magnitude plane, which is accessible by these compensators, is analytically found. Moreover, numerical examples and experimental results are presented to show the applicability of the achievements of this study in control system design
An evolutionary optimizing approach to neural network architecture for improving identification and modeling of aircraft nonlinear dynamics
, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Vol. 228, issue. 12 , 2014 , p. 2178-2191 ; Saghafi, F ; Sharif University of Technology
Abstract
In this paper, modified genetic algorithm has been used as a simultaneous optimizer of recurrent neural network to improve identification and modeling of aircraft nonlinear dynamics. Weighted connections, network architecture, and learning rules are features that play important roles in the quality of neural networks training and their generalizability in order to model nonlinear systems. Therefore, the main focus of this paper is to apply appropriate evolutionary methods in order to simultaneously optimize the parameters of neural networks for the improvement identification and modeling of aircraft nonlinear dynamics. To validate this study, the results have been compared with the recorded...
On type number concept in fractional-order systems
, Article Automatica ; Volume 49, Issue 1 , January , 2013 , Pages 301-304 ; 00051098 (ISSN) ; Sharif University of Technology
2013
Abstract
In this note, the type number concept is defined for fractional-order systems. Based on this definition, it is shown that fractional-order systems having type numbers more than 1 can not track some classes of reference inputs without any overshoot
PID controller design for micro gas turbines using experimental frequency-response data and a linear identification technique
, Article International Journal of Advanced Mechatronic Systems ; Volume 5, Issue 6 , 2013 , Pages 353-364 ; 17568412 (ISSN) ; Gol, H. A ; Ramazani, H ; Sharif University of Technology
E-flow Inderscience
2013
Abstract
This paper discusses the identification process of engine dynamics and presents derived transfer function models including; thrust, shaft speed, compressor exit pressure and turbine exit temperature in relation to the fuel flow. Model identification approach, presented in this paper, is the first to consider frequency-sweep signals to excite dynamics, as well as to utilise windowing and smoothing techniques to reduce random errors in the spectral estimates. Here, frequency sweep provides a fairly uniform spectral excitation and chirp-z transform warrants the exact determination of the frequency responses that are robust to the uncertainties. The identified models are also validated with the...
Design of fractional order proportional-integral-derivative controller based on moment matching and characteristic ratio assignment method
, Article Proceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering ; Volume 225, Issue 8 , December , 2011 , Pages 1040-1053 ; 09596518 (ISSN) ; Haeri, M ; Sharif University of Technology
2011
Abstract
This paper presents a new analytical method to design fractional-order proportional- integral-derivative (PID) controllers. The control parameters are calculated so that the closedloop system approximates a desired transfer function with transient response requirements. This function is determined based on the characteristic ratio assignment method. The control parameters are calculated by matching the first three moments of the closed-loop transfer function with the corresponding values of the desired system. Furthermore, to ensure closed-loop stability the proposed method is improved by using the shifted moments around the crossover frequency. Illustrative examples are given to show the...
Model predictive control of non-linear discrete time systems: A linear matrix inequality approach
, Article IET Control Theory and Applications ; Volume 4, Issue 10 , October , 2010 , Pages 1922-1932 ; 17518644 (ISSN) ; Taghirad, H. D ; Haeri, M ; Sharif University of Technology
2010
Abstract
Using a non-linear model in model predictive control (MPC) changes the control problem from a convex quadratic programme to a non-convex non-linear problem, which is much more challenging to solve. In this study, we introduce an MPC algorithm for non-linear discrete-time systems. The systems are composed of a linear constant part perturbed by an additive state-dependent non-linear term. The control objective is to design a state-feedback control law that minimises an infinite horizon cost function within the framework of linear matrix inequalities. In particular, it is shown that the solution of the optimisation problem can stabilise the non-linear plants. Three extensions, namely,...
The design of LQR and fuzzy logic controller for a thermal system with large time delay
, Article Proceedings of the 2010 International Conference on Mechanical, Industrial, and Manufacturing Technologies, MIMT 2010, 22 January 2010 through 24 January 2010 ; January , 2010 , Pages 293-298 ; 9780791859544 (ISBN) ; Jahromi, A. F ; Sarafan, A ; Akbar Khayyat, A. A ; Sharif University of Technology
2010
Abstract
This paper will first describe the Linear Quadratic Regulator (LQR) and Fuzzy logic controller when the Proportional-Integral-Derivative (PID) controllers are inactive for procedures that have large delay time (LDT) in transfer stage. Therefore in those states, LQR and Fuzzy controllers perform better than the PID controllers. The constrained LQR is optimal and stabilizing. The solution algorithm is guaranteed to terminate in finite time with a computational cost that has a reasonable upper bound compared to the minimal cost for computing the optimal solution. The system determines the amount of fuel required from a fuzzy algorithm to arrive at the desired temperature. The parameters of the...
A unified acceptance test framework for power plant gas turbine control systems
, Article ISA Transactions ; Volume 85 , February , 2018 , Pages 262-273 ; 00190578 (ISSN) ; Babazadeh, M ; Sharif University of Technology
ISA - Instrumentation, Systems, and Automation Society
2018
Abstract
Renovation and retrofit of gas turbine control systems yield significant economic savings, enhanced reliability, and improved performance. In recent years, the gas turbine industry is increasingly facing the need to well-established procedures for the acceptance tests of renovated control systems. This paper proposes a unified framework to evaluate the performance of renovated gas turbine control systems. Under a set of assumptions on the ambient and fuel conditions, a low-complexity modular model is presented and identified using optimization-oriented identification techniques. The accuracy of the proposed model is validated through experimental studies in full-load, min-load, and no-load...
Model predictive control of nonlinear discrete time systems with guaranteed stability
, Article Asian Journal of Control ; 2018 ; 15618625 (ISSN) ; Haeri, M ; Sharif University of Technology
Wiley-Blackwell
2018
Abstract
This paper presents the design of a new robust model predictive control algorithm for nonlinear systems represented by a linear model with unstructured uncertainty. The linear model is obtained by linearizing the nonlinear system at an operating point and the difference between the nonlinear and linear model is considered as a Lipschitz nonlinear function. The controller is designed for the linear model, which fulfills the stabilization condition for the nonlinear term. Unlike previous studies that have not considered a valid Lipschitz matrix of nonlinear term in the design process, we propose an algorithm in this paper in which it is considered. Therefore, the closed loop stability of the...
Comprehensive partial decoding approach for two-level relay networks
, Article IET Communications ; Volume 3, Issue 4 , 2009 , Pages 585-596 ; 17518628 (ISSN) ; Aref, M. R ; Sharif University of Technology
2009
Abstract
Partial decoding scheme is a scheme in which each relay decodes only part of the transmitted message. Obviously, the achievable rates proposed by the partial decoding scheme subsume the achievable rates proposed by the full decoding scheme. The other motivation of using partial decoding scheme is that there are some special classes of relay networks such as semi-deterministic and orthogonal relay networks such that their capacities are obtained via this scheme. The authors propose a comprehensive partial decoding scheme based on regular encoding/sliding window decoding analysis to propose a new achievable rate for two-level relay networks. In contrast with the previously proposed methods,...
Tight bound on the stability of control systems over parallel gaussian channels using a new joint source channel coding
, Article 2019 Iran Workshop on Communication and Information Theory, IWCIT 2019, 24 April 2019 through 25 April 2019 ; 2019 ; 9781728105840 (ISBN) ; Motahari, A. S ; Farhadi, A ; Khalaj, B. H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In this paper, we address the stability problem of a noiseless linear time invariant control system over parallel Gaussian channels with feedback. It is shown that the eigenvalues-rate condition which has been proved as a necessary condition, is also sufficient for stability over parallel Gaussian channels. In fact, it is proved that for stabilizing a control system over the parallel Gaussian channels, it suffices that the Shannon channel capacity obtained by the water filling technique is greater than the sum of the logarithm of the unstable eigenvalues magnitude. In order to prove this sufficient condition, we propose a new nonlinear joint source channel coding for parallel Gaussian...
A unified acceptance test framework for power plant gas turbine control systems
, Article ISA Transactions ; Volume 85 , 2019 , Pages 262-273 ; 00190578 (ISSN) ; Babazadeh, M ; Sharif University of Technology
ISA - Instrumentation, Systems, and Automation Society
2019
Abstract
Renovation and retrofit of gas turbine control systems yield significant economic savings, enhanced reliability, and improved performance. In recent years, the gas turbine industry is increasingly facing the need to well-established procedures for the acceptance tests of renovated control systems. This paper proposes a unified framework to evaluate the performance of renovated gas turbine control systems. Under a set of assumptions on the ambient and fuel conditions, a low-complexity modular model is presented and identified using optimization-oriented identification techniques. The accuracy of the proposed model is validated through experimental studies in full-load, min-load, and no-load...
Dynamic modeling, control system design and mil–hil tests of an unmanned rotorcraft using novel low-cost flight control system
, Article Iranian Journal of Science and Technology - Transactions of Mechanical Engineering ; 2019 ; 22286187 (ISSN) ; Salarieh, H ; Saadat Foumani , M ; Sharif University of Technology
Springer
2019
Abstract
Unmanned helicopters have gained great importance during recent years due to their special abilities such as hover flight, vertical take-off and landing, maneuverability and superior agility. The advances in electronic devices technologies lead to more powerful and lighter processors to be used in avionic systems which have attracted more attention to these UAVs. The first steps of utilizing an unmanned helicopter are dynamic modeling, control system design and performing model-in-the-loop (MIL) and hardware-in-the-loop (HIL) tests which are presented in this paper. In this research, MIL and HIL tests of an unmanned helicopter are done using novel Linux-based flight control system built on...