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robust-control
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Framework for robust blind image watermarking based on classification of attacks
, Article Multimedia Tools and Applications ; Volume 76, Issue 22 , 2017 , Pages 23459-23479 ; 13807501 (ISSN) ; Samavi, S ; Soroushmehr, S. M. R ; Shirani, S ; Karimi, N ; Najarian, K ; Sharif University of Technology
Abstract
With the widespread internet usage, digital contents are easily distributed throughout the world. To eliminate concerns of producers and owners of digital contents, watermarking techniques are extensively being used. Robustness against intentional and unintentional attacks is a major quality of watermarking systems. Since different attacks tend to target different parts of the frequency spectrum, in this paper we propose a framework for blind watermarking which determines the type of attack that the image has gone through before extracting the watermark. Within this framework, we propose an attack classification method to identify the region of the frequency spectrum that is less damaged....
Constrained tracking control for nonlinear systems
, Article ISA Transactions ; Volume 70 , 2017 , Pages 64-72 ; 00190578 (ISSN) ; Haeri, M ; Sharif University of Technology
Abstract
This paper proposes a tracking control strategy for nonlinear systems without needing a prior knowledge of the reference trajectory. The proposed method consists of a set of local controllers with appropriate overlaps in their stability regions and an on-line switching strategy which implements these controllers and uses some augmented intermediate controllers to ensure steering the system states to the desired set points without needing to redesign the controller for each value of set point changes. The proposed approach provides smooth transient responses despite switching among the local controllers. It should be mentioned that the stability regions of the proposed controllers could be...
A non parametric approach to monitor simple linear profiles in phases I and II
, Article Communications in Statistics - Theory and Methods ; Volume 46, Issue 11 , 2017 , Pages 5203-5222 ; 03610926 (ISSN) ; Akhavan Niaki, S. T ; Afshar Najafi, B ; Sharif University of Technology
Taylor and Francis Inc
2017
Abstract
In this paper, a non parametric approach is first proposed to monitor simple linear profiles with non normal error terms in Phase I and Phase II. In this approach, two control charts based on a transformation technique and decision on beliefs are designed in order to monitor the intercept and the slope, simultaneously. Then, some simulation experiments are performed in order to evaluate the performance of the proposed control charts in Phase II under both step and drift shifts in terms of out-of-control average run length (ARL1). Besides, the performance of the proposed control charts is compared to the ones of seven other existing schemes in the literature. Simulation results show that the...
A novel stable robust adaptive impedance control scheme for ankle prostheses
, Article 5th RSI International Conference on Robotics and Mechatronics, IcRoM 2017, 25 October 2017 through 27 October 2017 ; 2018 , Pages 63-68 ; 9781538657034 (ISBN) ; Sharifi, M ; Salarieh, H ; Alasty, A ; Sharif University of Technology
Abstract
A stable robust adaptive impedance control strategy is introduced here as a model-based low-level control scheme for active ankle prostheses. The effects of amputee-prosthesis and prosthesis-environment interactions are included in the controller design. An interesting feature of the proposed controller is that only shank and ankle angles and angular velocities, and ground reaction forces are required to implement the control law. In other words, no feedback from amputee-prosthesis interaction forces and moment, global or local positions, and accelerations of amputated place is required. Using a Lyapunov analysis, exponential convergence characteristics of the proposed controller are proven....
Impulsive synchronization of different hyperchaotic (chaotic) systems
, Article Chaos, Solitons and Fractals ; Volume 38, Issue 1 , 2008 , Pages 120-131 ; 09600779 (ISSN) ; Dehghani, M ; Sharif University of Technology
2008
Abstract
The impulsive synchronization has been employed to synchronize two different hyperchaotic (chaotic) systems. Conditions on impulse distances are given in order to obtain stable synchronization in the nominal case and robust stability in the case that we experience uncertainties in the systems dynamic and/or measurement noise. Under the given conditions, it is guaranteed that the error dynamics is asymptotically stable for the nominal case and convergent to a predetermined level for uncertain and/or noisy circumstances. Computer simulations are provided to assess results of the given theorems in the paper. © 2006 Elsevier Ltd. All rights reserved
Developing a robust ordering-based unstructured moving grid strategy
, Article 45th AIAA Aerospace Sciences Meeting 2007, Reno, NV, 8 January 2007 through 11 January 2007 ; Volume 24 , 2007 , Pages 17172-17184 ; 1563478900 (ISBN); 9781563478901 (ISBN) ; Darbandi, M ; Schneider, G. E ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc
2007
Abstract
In this work, a new method is presented to control the propagation of the boundary deformation within an unstructured mesh domain effectively and to avoid inefficient and unnecessary grid movement computations. In this regard, a new and simple automatic unstructured mesh ordering strategy is developed. The mesh movement algorithm automatically determines the regions, which are affected by the displacement propagation. The method needs little memory storage benefiting from an improved mesh data structure. We also present an improved acceleration strategy, which is highly consistent with the modified connectivity matrix and is able to handle a wide variety of problems with small and large...
Nonlinear feedback control of chaotic pendulum in presence of saturation effect
, Article Chaos, Solitons and Fractals ; Volume 31, Issue 2 , 2007 , Pages 292-304 ; 09600779 (ISSN) ; Salarieh, H ; Sharif University of Technology
2007
Abstract
In present paper, a feedback linearization control is applied to control a chaotic pendulum system. Tracking the desired periodic orbits such as period-one, period-two, and period-four orbits is efficiently achieved. Due to the presence of saturation in real world control signals, the stability of controller is investigated in presence of saturation and sufficient stability conditions are obtained. At first feedback linearization control law is designed, then to avoid the singularity condition, a saturating constraint is applied to the control signal. The stability conditions are obtained analytically. These conditions must be investigated for each specific case numerically. Simulation...
Bi-objective resource-constrained project scheduling with robustness and makespan criteria
, Article Applied Mathematics and Computation ; Volume 180, Issue 1 , 2006 , Pages 146-152 ; 00963003 (ISSN) ; Shadrokh, S ; Arkat, J ; Sharif University of Technology
2006
Abstract
Resource-constrained project scheduling problem (RCPSP) is one of the most important problems in the context of project scheduling. Considering a single objective, such as makespan minimization, net present value minimization or cost minimization has been the cornerstone of most studies done so far. At the other hand, taking this problem into account as a multi objective one has not been well studied. In this paper, a bi-objective model of RCPSP is presented. The first objective is makespan to be minimized, and the second one, a recently developed measure, is robustness maximization aimed at floating time maximization to make scheduling more reliable. The problem formed in this way is an...
Synchronization of chaotic systems using variable structure controllers
, 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) ; Alasty, A ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2006
Abstract
In this paper a variable structure system based upon sliding mode control with time varying sliding surface and variable boundary layer is introduced to synchronize two different chaotic systems with uncertain parameters. The method is applied to Lur'e-Genesio chaotic systems, as drive-response systems to investigate the effectiveness and robustness of the controlling method. In addition the simulation is repeated with a conventional sliding mode to compare the performance of the proposed sliding mode technique with a simple sliding mode control. The results show the high quality and improved performance of the method presented in the paper for synchronization of different drive-response...
Audio watermarking for covert communication through telephone system
, Article 6th IEEE International Symposium on Signal Processing and Information Technology, ISSPIT 2006, Vancouver, BC, 27 August 2006 through 30 August 2006 ; 2006 , Pages 955-959 ; 0780397541 (ISBN); 9780780397545 (ISBN) ; Vosoughi Vahdat, B ; Shamsollahi, M. B ; Sameni, R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2006
Abstract
In this paper, a novel service that uses audio watermarking for covert communication through telephone system is presented. This system is suitable for ISDN and PSIN networks and it can be modified for using in mobile systems. We use a Direct sequence spread spectrum algorithem with perceptual modeling of HAS for embedding watermark into the audio or speed signals. The watermark is robust against telephone channel attacks such as AWGN , Low pass filtering, D/A-A/D conversion, Downsampling down to 64 slips and A-Law or μ-Law conversion. This system is also robust against audio format conversion such as wave (windows PCM) format to mp3 (down o 64 kbps compression. © 2006 IEEE
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,...
Achieving higher perceptual quality and robustness in watermarking using Julian set patterns
, Article IEE Proceedings: Information Security ; Volume 153, Issue 4 , 2006 , Pages 167-172 ; 17470722 (ISSN) ; Jamzad, M ; Sharif University of Technology
2006
Abstract
Some of the most important classes of watermark detection methods in image watermarking are correlation-based algorithms. In these methods usually a pseudorandom noise pattern is embedded in the host image. The receiver can regenerate this pattern by having a key that is the seed of a random number generator. After that if the correlation between this pattern and the image that is assumed to have the watermark is higher than a predefined threshold, it means that the watermark exists and vice versa. Here, we show the advantage of using the Julian set patterns as a watermark, instead of the commonly used pseudorandom noise pattern. Julian set patterns can be regenerated in receiver with few...
Output feedback decentralized control of multi-agent manipulation systems
, Article IEEE International Conference on Engineering of Intelligent Systems, ICEIS 2006, Islamabad, 22 April 2006 through 23 April 2006 ; 2006 ; 1424404568 (ISBN); 9781424404568 (ISBN) ; Elhamifar, E ; Sharif University of Technology
2006
Abstract
In this paper, decentralized control algorithms for cooperative multi-agent manipulation systems are developed. To control the positions of the agents and the exerted forces on the object in the presence of uncertainties in the dynamics of the agents, two different methods are considered. In the first approach, robust control of the system is proposed. Using the Lyapunov stability method, the convergence of the position errors to zero is demonstrated. Also a bound on the errors of the exerted forces is achieved which can be made small enough by choosing the appropriate estimated values for the physical parameters of the agents. In the second approach, adaptive control algorithm is proposed...
Modelling of a complex system using the dynamic rule prediction
, Article WSEAS Transactions on Systems ; Volume 5, Issue 12 , 2006 , Pages 2833-2838 ; 11092777 (ISSN) ; Jafarijashemi, G ; Zohoor, H ; Sharif University of Technology
2006
Abstract
Presented in this paper are a method, named the Dynamic Rule Prediction (DRP), which predicts the behavior of a system and its application in designing a controller. The aim of the study is to overcome some of the limitations and shortcoming of the other modeling methods. The effectiveness of this method is verified. The controller based on DRP possesses two main features. It can control the system without any prior knowledge of the controlled plant. It is, also, superior as its high-speed prediction. This paper focuses on the robot manipulator controllers and applications of this approach in it
Robust control of smart beam with pizoelectric actuators
, Article Eight IASTED International Conference on Control and Applications, Montreal, QC, 24 May 2006 through 26 May 2006 ; Volume 2006 , 2006 , Pages 41-47 ; 0889865531 (ISBN); 9780889865532 (ISBN) ; Yousefi Koma, A ; Akbari, S ; Zadeh, B. T ; Sharif University of Technology
2006
Abstract
In this paper, a robust control system is developed for a flexible beam with piezoelectric actuators (called Smart Beam). The active control system of smart beam satisfied desired properties for all admissible measurement and plant noises, disturbances and model uncertainties. Thus it is the best candidate for sensitive industrial, medical and etc. robot arms and bases a new concept in the use of smart structures in robotics. The Frequency Response Function (FRF) of the smart beam was obtained from a Finite Element (FE) model. The corresponding transfer function was derived from the □ synthesis and several control schemes were then designed to suppress the vibration. Results showed the...
Meshless local petrov-galerkin (MLPG) method for incompressible viscous fluid flows
, Article 2006 2nd ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006, Miami, FL, 17 July 2006 through 20 July 2006 ; Volume 2006 , 2006 ; 0791837831 (ISBN); 9780791837832 (ISBN) ; Sharif University of Technology
2006
Abstract
In this paper, the truly Meshless Local Petrov-Galerkin (MLPG) method is extended for computation of unsteady incompressible flows, governed by the Navier-Stokes equations (NSE), in vorticity-stream function formulation. The present method is a truly meshless method based only on a number of randomly located nodes. The formulation is based on two equations including stream function Poisson equation and vorticity advection-dispersion-reaction eq. (ADRE). The meshless method is based on a local weighted residual method with the Heaviside step function and quartic spline as the test functions respectively over a local subdomain. Moving Least Square approximation (MLS) is employed in shape...
Observer-based control design for three well-known chaotic systems
, Article Chaos, Solitons and Fractals ; Volume 29, Issue 2 , 2006 , Pages 381-392 ; 09600779 (ISSN) ; Shahrokhi, M ; Pishkenari, H. N ; Sharif University of Technology
2006
Abstract
In this paper, a singularity-free approach is proposed for controlling three well-known chaotic systems namely Lorenz, Chen and Lu. The control design guarantees the regulation of two states and boundedness of the remaining state. The stability of the proposed scheme has been shown using the Lyapunov stability theorem. Implementation of the proposed control technique requires system states, while in most of practical applications only the system output is available. To overcome this problem, a nonlinear observer is coupled with the controller. Simulation results have illustrated the effectiveness and robustness of the proposed schemes. If the control action is applied to the second system...
Low-order H∞ controller design for an active suspension system via LMIs
, Article IEEE Transactions on Industrial Electronics ; Volume 53, Issue 2 , 2006 , Pages 554-560 ; 02780046 (ISSN) ; Sadati, N ; Sharif University of Technology
2006
Abstract
An application of a new controller order reduction technique with stability and performance preservation based on linear matrix inequality optimization to an active suspension system is presented. In this technique, the rank of the residue matrix of a proper rational approximation of a high-order H∞controller subject to the H∞-norm of a frequency-weighted error between the approximated controller and the high-order H∞ controller is minimized. However, because solving this matrix rank minimization problem is very difficult, the rank objective function is replaced with a nuclear-norm that can be reduced to a semidefinite program so that it can be solved efficiently. Application to the active...
A systematic decomposition approach of nonlinear systems by combining gap metric and stability margin
, Article Transactions of the Institute of Measurement and Control ; Volume 43, Issue 9 , 2021 , Pages 2006-2017 ; 01423312 (ISSN) ; Haeri, M ; Sharif University of Technology
SAGE Publications Ltd
2021
Abstract
In this paper, in order to control a nonlinear dynamic system via multi-model controller, we propose a systematic approach to determine the nominal local linear models. These models are selected from the local models bank and results in a reduced nominal models set that provides enough information to design a multi-model controller. To determine the initial local models bank, gap metric is used so that the distance between two successive local models is smaller than a threshold value. Then, a systematic approach that aims to get a reduced nominal models bank is developed. Based on this approach, first, a binary gap matrix is defined by combining gap metric and stability information. Then,...
A systematic decomposition approach of nonlinear systems by combining gap metric and stability margin
, Article Transactions of the Institute of Measurement and Control ; Volume 43, Issue 9 , 2021 , Pages 2006-2017 ; 01423312 (ISSN) ; Haeri, M ; Sharif University of Technology
SAGE Publications Ltd
2021
Abstract
In this paper, in order to control a nonlinear dynamic system via multi-model controller, we propose a systematic approach to determine the nominal local linear models. These models are selected from the local models bank and results in a reduced nominal models set that provides enough information to design a multi-model controller. To determine the initial local models bank, gap metric is used so that the distance between two successive local models is smaller than a threshold value. Then, a systematic approach that aims to get a reduced nominal models bank is developed. Based on this approach, first, a binary gap matrix is defined by combining gap metric and stability information. Then,...