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parametric-uncertainty
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Robust modeling, sliding-mode controller, and simulation of an underactuated rov under parametric uncertainties and disturbances
, Article Journal of Marine Science and Application ; 2018 ; 16719433 (ISSN) ; Chin, C. S ; Nobakhti, A ; Sharif University of Technology
Harbin Engineering University
2018
Abstract
A dynamic model of a remotely operated vehicle (ROV) is developed. The hydrodynamic damping coefficients are estimated using a semi-predictive approach and computational fluid dynamic software ANSYS-CFX™ and WAMIT™. A sliding-mode controller (SMC) is then designed for the ROV model. The controller is subsequently robustified against modeling uncertainties, disturbances, and measurement errors. It is shown that when the system is subjected to bounded uncertainties, the SMC will preserve stability and tracking response. The paper ends with simulation results for a variety of conditions such as disturbances and parametric uncertainties. © 2018, Harbin Engineering University and Springer-Verlag...
Robust modeling, sliding-mode controller, and simulation of an underactuated rov under parametric uncertainties and disturbances
, Article Journal of Marine Science and Application ; Volume 18, Issue 2 , 2019 , Pages 213-227 ; 16719433 (ISSN) ; Chin, C. S ; Nobakhti, A ; Sharif University of Technology
Harbin Engineering University
2019
Abstract
A dynamic model of a remotely operated vehicle (ROV) is developed. The hydrodynamic damping coefficients are estimated using a semi-predictive approach and computational fluid dynamic software ANSYS-CFX™ and WAMIT™. A sliding-mode controller (SMC) is then designed for the ROV model. The controller is subsequently robustified against modeling uncertainties, disturbances, and measurement errors. It is shown that when the system is subjected to bounded uncertainties, the SMC will preserve stability and tracking response. The paper ends with simulation results for a variety of conditions such as disturbances and parametric uncertainties. © 2018, Harbin Engineering University and Springer-Verlag...
Robustness margin in linear time invariant fractional order systems
, Article IFAC Proceedings Volumes (IFAC-PapersOnline), 15 September 2010 through 17 September 2010 ; 2010 , Pages 198-203 ; 14746670 (ISSN) ; 9783902661838 (ISBN) ; Haeri, M ; Sharif University of Technology
Abstract
In this paper, the computation of robustness margin for linear time invariant fractional order systems is studied. For the definition of robustness margin, we employ the one introduced for polynomials (i.e. integer order) and extend it to fractional order functions. Using the well known concept of the value set and knowing its shape for the intended functions, this paper presents an easy way to obtain the robustness margin for fractional order systems. To illustrate the results, a numerical example is provided
On robust stability of LTI fractional-order delay systems of retarded and neutral type
, Article Automatica ; Volume 46, Issue 2 , 2010 , Pages 362-368 ; 00051098 (ISSN) ; Haeri, M ; Sharif University of Technology
2010
Abstract
This paper deals with the analysis of robust BIBO-stability of LTI fractional order delay systems in the presence of real parametric uncertainties. Two large classes of these systems, namely retarded and neutral types, are considered. Two theorems are given to check the robust BIBO-stability of these two families of fractional order systems. One of these theorems provides necessary and sufficient conditions for the case of retarded type and another one presents only sufficient conditions for the case of neutral type. Furthermore, upper and lower bounds (cutoff frequencies) are provided for drawing the value sets. To illustrate the results, two numerical examples are presented
A probabilistic framework to achieve robust non-fragile tuning methods: PD control of IPD-modeled processes
, Article International Journal of Robust and Nonlinear Control ; 2021 ; 10498923 (ISSN) ; Tavazoei, M. S ; Sharif University of Technology
John Wiley and Sons Ltd
2021
Abstract
We introduce a novel probabilistic framework to achieve robust non-fragile tuning methods in control of processes with parametric uncertainties. We consider probability distributions to model the process parameters' uncertainties. First, we propose the tuning framework in a general setting. Then, as an illustration, we apply it to PD control of IPD-modeled processes. It is noteworthy that the proposed tuning method is robust against the considered parametric uncertainties. Also, to empower the proposed robust tuning method in the viewpoint of non-fragility, we utilize a centroid approach. Selecting the form of the probabilistic framework, we empirically observe some of the popular tuning...
Robust stable control of haptic devices based on transparency maximization
, Article ASME 2010 International Mechanical Engineering Congress and Exposition, IMECE 2010, Vancouver, BC, 12 November 2010 through 18 November 2010 ; Volume 8, Issue PARTS A AND B , 2010 , Pages 773-780 ; 9780791844458 (ISBN) ; Ahmadian, M ; Vossoughi, G ; Sharif University of Technology
2010
Abstract
Performance of a haptic device is evaluated based on the concept of transparency. Stability of a haptic device prevalently has been evaluated based on the passivity criterion. Due to conservativeness of passivity, it appears as an obstacle to improve transparency. In this paper, passivity is suggested to be replaced by the complementary stability criterion which accounts for the robust stability of the interaction in the presence of uncertain user hand dynamics. In this respect, an algorithm is proposed which guarantees transparency of the haptic device in a stable manner. Assuming that the dynamics of the device is known, a certain compensatory structure is assigned. This special structure...
Optimal robust control of drug delivery in cancer chemotherapy: A comparison between three control approaches
, Article Computer Methods and Programs in Biomedicine ; Volume 112, Issue 1 , 2013 , Pages 69-83 ; 01692607 (ISSN) ; Vossoughi, G ; Salarieh, H ; Sharif University of Technology
2013
Abstract
During the drug delivery process in chemotherapy, both of the cancer cells and normal healthy cells may be killed. In this paper, three mathematical cell-kill models including log-kill hypothesis, Norton-Simon hypothesis and Emax hypothesis are considered. Three control approaches including optimal linear regulation, nonlinear optimal control based on variation of extremals and H∞-robust control based on μ-synthesis are developed. An appropriate cost function is defined such that the amount of required drug is minimized while the tumor volume is reduced. For the first time, performance of the system is investigated and compared for three control strategies; applied on three nonlinear models...
Multivariable optimal control of an industrial nonlinear boiler–turbine unit
, Article Meccanica ; Volume 51, Issue 4 , 2016 , Pages 859-875 ; 00256455 (ISSN) ; Vossoughi, G ; Sharif University of Technology
Abstract
Performance control of a boiler–turbine unit is of great importance due to demands for the economical operations of power plants and environmental awareness. In this paper, an optimal control strategy is designed to achieve the desired performance of a boiler–turbine unit. A multivariable nonlinear model of a utility boiler–turbine unit is considered. By manipulation of valves position for the fuel, steam and feed-water flows; output variables including the drum pressure, electric output and fluid density (and consequently drum water level) are controlled. Performance measure of the problem is defined such that the control efforts are minimized while the tracking objectives are obtained. In...
Robust stable control of haptic devices based on transparency maximization
, Article Proceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering ; Volume 225, Issue 7 , 2011 , Pages 954-967 ; 09596518 (ISSN) ; Vossoughi, G ; Tajaddodianfar, F ; Sharif University of Technology
2011
Abstract
The performance of hapticdevicesisevaluatedbasedontheconceptoftransparency, whiletheirstabilityhasprevalentlybeenevaluatedbasedonthepassivitycriterion. Duetotheconservativenessofpassivity, itappearsasanobstacletoimprovingtransparency.Inthepresentpaper, passivityissuggestedtobereplacedbythecomplementarystabilitycriterionwhichaccoun tsfortherobuststabilityoftheinteractioninthepresnceofuncertainuserhanddynamics. Inthisrespect, analgorithmisproposedwhichguaranteestransparencyofthehapticdeviceinastablemanne r.Assumingthatthedynamicsofthedeviceisknown, acertaincompensatorystructureisassigned. Thisspecialstructureguaranteestransparencyofthedevicebycompensatingforthedynami...
PID-Fuzzy control of air handling units in the presence of uncertainty
, Article International Journal of Thermal Sciences ; Volume 109 , 2016 , Pages 123-135 ; 12900729 (ISSN) ; Setayesh, H ; Alasty, A ; Sharif University of Technology
Elsevier Masson SAS
Abstract
Air-handling unit (AHU) is one of the most complex installations that its control is necessary for maintaining satisfactory comfort conditions in buildings with low energy utilization. In this paper, a multivariable nonlinear and minimum phase model of the AHU is considered in the presence of uncertainties. The controller design is divided into two types. The first controller type is for the linearized plant based on decoupled PID-Fuzzy and PD-type Fuzzy controllers. The second type is based on full matrix PID-Fuzzy and pole-placement controllers in which interaction effects are considered. The indoor temperature and relative humidity are controlled via manipulation of valve positions of air...
Design of sliding mode and model reference adaptive control strategies for multivariable tape transport mechanism: a performance comparison
, Article Microsystem Technologies ; Volume 22, Issue 2 , 2016 , Pages 419-431 ; 09467076 (ISSN) ; Moradian, H ; Moradi, H ; Sharif University of Technology
Springer Verlag
Abstract
This paper presents sliding mode control and model reference adaptive control strategies for the tape transport mechanism. A nonlinear multivariable MIMO model of the process, consisting of take-up and supply reel servos for tape tension control and capstan servo for speed control is considered. The sliding mode control is applied for the nonlinear dynamic model of the process, while the model reference adaptive control deals with the linearized one. Moreover, in order to associate with the realistic model of system, design of controllers is accomplished with respect to parametric uncertainties. It is shown that both control strategies can guarantee asymptotic stability of the closed-loop...
Adaptive boundary control of the size-dependent behavior of euler-bernoulli micro-beams with unknown parameters and varying disturbance
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 231, Issue 10 , 2017 , Pages 1777-1790 ; 09544062 (ISSN) ; Vatankhah, R ; Salarieh, H ; Sharif University of Technology
Abstract
In this paper, modeling and vibration control of a strain-gradient clamped-free Euler-Bernoulli micro-beam exposed to varying disturbance is studied. A strain-gradient model of the Euler-Bernoulli micro-beam is represented in this paper and consisted of one partial differential equation and six ordinary equations as governing motion equation and boundary conditions, respectively. A boundary controller is proposed to suppress the system's vibration. The controller is derived based on the direct Lyapunov method. An adaptation law is devised to assure system's stability under parametric uncertainties. With the proposed adaptive robust boundary control, uniform boundedness under environmental...
Robust ground reaction force estimation and control of lower-limb prostheses: theory and simulation
, Article IEEE Transactions on Systems, Man, and Cybernetics: Systems ; 2018 ; 21682216 (ISSN) ; Nguyen, T. T ; Sharifi, M ; Fakoorian, A ; Simon, D ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Ground reaction force (GRF) characteristics of amputee walking are important for the analysis of clinical gait data, and also to update model reference adaptive impedance (MRAI) controllers. GRF estimation is a better alternative than direct GRF measurement because of the disadvantages of load cells, such as high cost, integration difficulties due to weight and physical dimensions, the possibility of overload, and measurement noise. This paper presents four robust MRAI observer/controller combinations for GRF estimation-based control of a prosthesis and a legged robot model in the presence of parametric uncertainties and unmodeled dynamics, in which the robot model is employed to mimic...
Sliding mode control of the turning process for eliminating regenerative chatter in the presence of parametric uncertainties
, Article ASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007, 11 November 2007 through 15 November 2007 ; Volume 3 , 2007 , Pages 449-456 ; 0791842975 (ISBN) ; Movahhedy, M. R ; Vossoughi, G. R ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2007
Abstract
Chatter suppression is an important topic in any type of machining process. In this paper, orthogonal cutting process is modeled as a single degree of freedom dynamic system. A nonlinear delay differential equation is presented that models flank wear of the tool. Uncertainties in cutting velocity, tool wear size and parameters of the dynamic model are included in the model of cutting process. The force provided by a piezo-actuator is taken as the control input of the system. A sliding mode control scheme is used and an effective control law is derived which suppresses the chatter vibration. Results for two distinct cases of a sharp tool and a worn tool are presented and compared which shows...
Design of robust control strategy in drug and virus scheduling in nonlinear process of chemovirotherapy
, Article Computers and Chemical Engineering ; Volume 150 , 2021 ; 00981354 (ISSN) ; Moradi, H ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Since the injection of the oncolytic viruses in the virotherapy process reduces the toxicity and drug resistance inherent in the chemotherapy; chemovirotherapy as a novel combination therapy has become an efficient cancer treatment. The primary purpose of this paper is to design a robust optimal control strategy for the chemovirotherapy through which the tumor density decreases to its stable condition with limited drug and virus delivery. This desired treatment should be responsive in the presence of input disturbances and parametric uncertainties. In this regard, an ODE (Ordinary Differential Equation) mathematical model of the chemovirotherapy process presenting the connection between the...
On robust stability of linear time invariant fractional-order systems with real parametric uncertainties
, Article ISA Transactions ; Volume 48, Issue 4 , 2009 , Pages 484-490 ; 00190578 (ISSN) ; Haeri, M ; Sharif University of Technology
2009
Abstract
In this paper, the robust bounded-input bounded-output stability of a large class of linear time invariant fractional order families of systems with real parametric uncertainties is analyzed. The transfer functions contain polynomials in fractional powers of the Laplace variable s, possibly in combination with exponentials of fractional powers of s. Using the concept of the value set and a generalization of the zero exclusion condition theorem, a theorem to check the robust bounded-input bounded-output stability of these families of systems is presented. An upper cutoff frequency for drawing the value sets is provided as well. Finally, two numerical examples are given to illustrate results...
Robust Stability Analysis of a Family of Fractional Order Systems with Structured Real Parametric Uncertainties
, Ph.D. Dissertation Sharif University of Technology ; Haeri, Mohammad (Supervisor)
Abstract
Transfer functions of some important classes of infinite-dimensional LTI systems contain semi-polynomials in fractional powers of Laplace variable , possibly in combination with delay terms or exponentials of fractional powers of . They can be observed in many systems and subjects such as biological systems, distributed parameter systems and heat flowing phenomena. Some appropriate theorems relevant to the subject of BIBO-stability are available for a large class of such systems, though many difficulties arise in applying them analytically. In this work, some parameters of the transfer functions of such systems (e.g., the coefficients of the numerators and denominators) are considered as...
Robust regulation and tracking system design for multivariable control of the tape transport mechanism
, Article Microsystem Technologies ; Vol. 18, Issue. 5 , 2012 , pp. 557-573 ; ISSN: 09467076 ; Bakhtiari-Nejad, F ; Alasty, A ; Sharif University of Technology
Abstract
Tape mechanisms must be able to transport the tape with a constant velocity for achieving high rate of data transfer. In this paper, a multivariable model of tape transport mechanism including the take-up and supply reel servos for tape tension control and capstan servo for speed control is considered. To achieve desired performance,pole-placement approach based on general canonical control form (GCCF) is used. Instead of using expensive tension sensors, an observer is designed. A regulator system is developed for disturbance rejection; and a modified integral control is designed for perfect tracking of desired setpoints in tape speed and tensions. Since the real dynamic model associates...
Robust regulation and tracking system design for multivariable control of the tape transport mechanism
, Article Microsystem Technologies ; Volume 18, Issue 5 , 2012 , Pages 557-573 ; 09467076 (ISSN) ; Bakhtiari Nejad, F ; Alasty, A ; Sharif University of Technology
2012
Abstract
Tape mechanisms must be able to transport the tape with a constant velocity for achieving high rate of data transfer. In this paper, a multivariable model of tape transport mechanism including the take-up and supply reel servos for tape tension control and capstan servo for speed control is considered. To achieve desired performance,pole-placement approach based on general canonical control form (GCCF) is used. Instead of using expensive tension sensors, an observer is designed. A regulator system is developed for disturbance rejection; and a modified integral control is designed for perfect tracking of desired setpoints in tape speed and tensions. Since the real dynamic model associates...
Nonlinear robust adaptive Cartesian impedance control of UAVs equipped with a robot manipulator
, Article Advanced Robotics ; Volume 29, Issue 3 , Feb , 2015 , Pages 171-186 ; 01691864 (ISSN) ; Sayyaadi, H ; Sharif University of Technology
Robotics Society of Japan
2015
Abstract
In this paper, a new nonlinear robust adaptive impedance controller is addressed for Unmanned Aerial Vehicles (UAVs) equipped with a robot manipulator that physically interacts with environment. A UAV equipped with a robot manipulator is a novel system that can perform different tasks instead of human being in dangerous and/or inaccessible environments. The objective of the proposed robust adaptive controller is control of the UAV and its robotic manipulators end-effector impedance in Cartesian space in order to have a stable physical interaction with environment. The proposed controller is robust against parametric uncertainties in the nonlinear dynamics model of the UAV and the robot...