Search for: closed-loop-control
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    Development of a hybrid reference model for performance evaluation of resolvers

    , Article IEEE Transactions on Instrumentation and Measurement ; Volume 70 , 2021 ; 00189456 (ISSN) Khajueezadeh, M ; Saneie, H ; Nasiri Gheidari, Z ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2021
    Resolver is an electromagnetic position sensor typically used in the closed-loop control of permanent magnet synchronous motors (PMSMs). In terms of structure and principle of operation, resolvers are very similar to electrical machines. In this regard, different numerical and analytical models have been developed for the performance prediction of a resolver, with a compromise between computational burden and accuracy. Therefore, a fast and accurate hybrid model of the resolver is presented in this article, which can be used for resolvers with different structures. Additionally, this model can easily be implemented in software such as MATLAB/SIMULINK. The performance of different variable... 

    A novel voltage measurement technique for modular multilevel converter capacitors

    , Article 41st Annual Conference of the IEEE Industrial Electronics Society, 9 November 2015 through 12 November 2015 ; 2015 , Pages 238-243 ; 9781479917624 (ISBN) Haghnazari, S ; Zolghadri, M. R ; IEEE Industrial Electonics Society (IES) ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    In this paper a new voltage measurement technique for modular multilevel converter (MMC) capacitors is proposed. While all the capacitors voltages should be known for closed loop control of MMCs, only the arms voltages are measured employing the proposed method. Therefore, the number of voltage sensors reduced dramatically to one per arm. The capacitors voltage quantities are updated continuously using the arms voltage and the switching signals. Although the proposed method precision is depended on the equality of the capacitors, presented investigations show that the steady state error and even transient error in capacitors voltage estimation is ignorable for the proper operation of the... 

    Design of an stable GPC for nonminimum phase LTI systems

    , Article Wec 05: Fourth World Enformatika Conference, Istanbul, 24 June 2005 through 26 June 2005 ; Volume 6 , 2005 , Pages 88-91 ; 9759845857 (ISBN); 9789759845858 (ISBN) Yaghobi, M ; Haeri, M ; Sharif University of Technology
    The current methods of predictive controllers are utilized for those processes in which the rate of output variations is not high. For such processes, therefore, stability can be achieved by implementing the constrained predictive controller or applying infinite prediction horizon. When the rate of the output growth is high (e.g. for unstable nonminimum phase process) the stabilization seems to be problematic. In order to avoid this, it is suggested to change the method in the way that: first, the prediction error growth should be decreased at the early stage of the prediction horizon, and second, the rate of the error variation should be penalized. The growth of the error is decreased... 

    A novel method on singularity analysis in parallel manipulators

    , 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) Pendar, H ; Mahnama, M ; Zohoor, H ; Sharif University of Technology
    American Society of Mechanical Engineers  2006
    A parallel manipulator is a closed loop mechanism in which a moving platform is connected to the base by at least two serial kinematic chains. The main problem engaged in these mechanisms, is their restricted working space as a result of singularities. In order to tackle these problems, many methods have been introduced by scholars. However, most of the mentioned methods are too much time consuming and need a great amount of computations. They also in most cases do not provide a good insight to the existence of singularity for the designer. In this paper a novel approach is introduced and utilized to identify singularities in parallel manipulators. By applying the new method, one could get a... 

    Analysis of the convergence and closed loop stability in EDMC

    , Article Scientia Iranica ; Volume 12, Issue 1 , 2005 , Pages 43-54 ; 10263098 (ISSN) Haeri, M ; Zadehmorshed Beik, H ; Sharif University of Technology
    Sharif University of Technology  2005
    In this paper, the convergence and stability conditions of extended DMC in the control of nonlinear SISO and MIMO systems are investigated. The formulations are based on the ordinary DMC in which, with successive linearization of the nonlinear model and new interpretation of disturbance, the nonlinear extension is deduced. In addition, new convergence and stability criteria are derived for SISO and MIMO systems. These criteria include convergence and stability in the case of longer control (M > 1) and prediction (P > 1) horizons, as well as the finite and infinite sampling time. Finally, the simulation results for a MIMO (3 × 3) model, based on a power unit nonlinear plant, are presented. ©... 

    Exact solutions for universal holonomic quantum gates

    , Article Physical Review A - Atomic, Molecular, and Optical Physics ; Volume 70, Issue 1 , 2004 , Pages 012320-1-012320-5 ; 10502947 (ISSN) Karimipour, V ; Majd, N ; Sharif University of Technology
    American Physical Society  2004
    Implementation of local quantum gate on specific qubits in an array of qubits by carrying a Hamiltonian around a closed loop is discussed. A family of isospectral Hamiltonians with the same spectrum of the projection operator on the main array is constructed by choice of a suitable curve. For every single qubit gate acting on the k-th qubit, a local operator Xk acts nontrivially on the ancilla and the qubit. Imbedding appropriate operators for a suitable set of qubit gates comprises of a universal set of quantum gates. In tensor product of the array one can enact holonomically any set of gates on any subset of qubits  

    Extension of nonlinear DMC for MIMO systems

    , Article Fourth International Conference on Control and Automation, Montreal, Que., 10 June 2003 through 12 June 2003 ; 2003 , Pages 375-379 ; 078037777X (ISBN); 9780780377776 (ISBN) Haeri, M ; Beik, H. Z ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2003
    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, M, and prediction, P, horizons that are required to increase the performance of the controller in most practical applications. Simulation results of the proposed method in the control of a stirred tank reactor with 2 inputs and 2 outputs nonlinear model are presented to illustrate effectiveness of the method and its justification. © 2003 IEEE  

    Closed-loop finite element modeling for analysis of smart structures in ansys environment

    , 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) Mahboobi, S. H ; Shahidi, A ; Abedian, A ; Meghdari, A ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2006
    It would be promising if one can simulate the closed-loop behavior of a smart system in an available FEM software such as "ANSYS". The ANSYS/Multiphysics software has the ability of coupling different physical domains and also modeling smart materials such as piezoelectric and piezoresistives, i.e. it has the capability of modeling smart structures. The dynamic modeling of the controlled structures is then realized by the ANSYS programming tool. This aspect highly facilitates the overall system behavior analysis and at the same time various control methods can be tested without noticing the time consuming structural analysis involved. In this research work, it is tried the mentioned idea to... 

    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) Azarsina, F ; Sayyaadi, H ; Sharif University of Technology
    American Society of Mechanical Engineers  2006
    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,... 

    Application of neural networks to decentralized control of robot manipulators with high degree of freedom

    , 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 484-488 ; 10823409 (ISSN); 0769524885 (ISBN); 9780769524887 (ISBN) Sadati, N ; Elhamifar, E ; Sharif University of Technology
    In this paper a neural network decentralized control for trajectory tracking of robot manipulators is developed. The proposed decentralized control allows the overall closed-loop system to be stabilized while making the tracking error to be uniformly ultimately bounded (UUB), without having any prior knowledge of the robot manipulator dynamics. The interconnections in the dynamic equations of each subsystem are considered with unknown nonlinear bounds. The RBF neural networks (RBFNNs) are proposed to model the unknown nonlinear dynamics of the robots and the interconnection terms. Using Lyapunov method, the stability of the overall system is investigated, © 2005 IEEE  

    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) Ghafari, A. S ; Behzad, M ; Sharif University of Technology
    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) Shoeybi, M ; Ghorashi, M ; Sharif University of Technology
    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... 

    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) Sadati, N ; Elhamifar, E ; Sharif University of Technology
    IEEE Computer Society  2005
    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.... 

    Position control of ionic polymer-metal composites using fuzzy logic

    , Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 11 , 2009 , Pages 575-581 ; 9780791848722 (ISBN) Radmard, S ; Honarvar, M ; Alasty, A ; Meghdari, A ; Zohor, H ; Sharif University of Technology
    The Ionic polymer-metal composites (IPMCs) form an important category of electroactive polymers which generate large deformation under a low driving voltage. In this paper an empirical model of IPMC is developed by measuring the step response of a 23 mmx3.6 mmx0.16 mm IPMC strip in a cantilever configuration. Moreover, a model-based precision position control of an IPMC base on the fuzzy logic is presented. Open-loop position responses of an IPMC are not repeatable, and hence closed-loop precision control is of critical importance to ensure proper functioning, repeatability and reliability. A CCD camera was used to observe the closed loop response of the IPMC strip in order to control this... 

    Position Error of Resolver in a Closed Loop Control

    , M.Sc. Thesis Sharif University of Technology Khajueezadeh Ravari, Mohammad Sadegh (Author) ; Nasiri Gheidari, Zahra (Supervisor)
    Permanent Magnet Synchronous Motors (PMSMs) are more conventional and widely employed in Electric Vehicles (EVs) applications. The rotor position performed an essential role through PMSMs drive; therefore, any deviation in the detected position will be evaded in coordinate transformations, originating from external or inherence sources. Subsequently, the discussed faults will be conducted to three-phase currents and output torque through erroneous transformations. Resolver’s estimated rotor position due to fault occurrence will be defined as aggregating ideal and non-ideal components. Moreover, based on inherence periodic in resolvers’ principle, non-ideal components could be written by the... 

    Maestro: A high performance AES encryption/decryption system

    , Article Proceedings - 17th CSI International Symposium on Computer Architecture and Digital Systems, CADS 2013 ; October , 2013 , Pages 145-148 ; 9781479905621 (ISBN) Biglari, M ; Qasemi, E ; Pourmohseni, B ; Computer Society of Iran; IPM ; Sharif University of Technology
    IEEE Computer Society  2013
    High throughput AES encryption/decryption is a necessity for many of modern embedded systems. This article presents a high performance yet cost efficient AES system. Maestro can be used in a wide range of embedded applications with various requirements and limitations. Maestro is about one million times faster than the pure software implementation. The Maestro architecture is composed of two major components; the soft processor aimed at system initialization and control, and the hardware AES engine for high performance AES encryption/decryption. A ten stage implicit pipelined architecture is considered for the AES engine. Two novel techniques are proposed in design of AES engine which enable... 

    CRA based control of fractional order systems subject to control signal constraint

    , Article International Conference on Control, Automation and Systems ; 2011 , Pages 268-272 ; 15987833 (ISSN) ; 9781457708350 (ISBN) Tabatabaei, M ; Haeri, M ; Sharif University of Technology
    An approach is proposed to control transient response of fractional order systems with maximum permissible control signal. This goal is achieved using a newly suggested characteristic ratio assignment method. Based on the proposed method, the generalized time constant τ and the characteristic ratios including their pattern, an adjustable parameter β, and the product of two successive characteristic ratios ρ are determined such that predefined level of overshoot and time specification of closed loop step response are obtained while the control signal is confined to a pre assigned maximum magnitude. The raised issue is solved by defining an optimization problem in which the design parameters... 

    Simulation and control of monomer conversion in a continuous emulsion polymerization reactor

    , Article IFAC Proceedings Volumes (IFAC-PapersOnline), 7 June 2015 through 10 June 2015 ; Volume 48, Issue 8 , 2015 , Pages 315-320 ; 14746670 (ISSN) Barazandegan, M ; Shahrokhi, M ; Abedini, H ; Vafa, E ; Guay, M ; Gopaluni, B ; Huang, B ; Findeisen, R ; Sharif University of Technology
    IFAC Secretariat  2015
    A detailed pseudo-bulk model has been used for prediction of conversion and particle size distribution (PSD) of vinyl acetate in a continuous emulsion polymerization reactor. Finite volume (FV) and moment techniques are applied for solving population balance equation under continuous operation. It is found that both methods can predict sustained oscillations in the monomer conversion, however the FV method matches the experimental data better than the moment method. The monomer conversion and free surfactant concentration are controlled via two single control loops. In this work, a new control strategy for controlling monomer conversion has been proposed. It has been shown that monomer... 

    Adaptive prescribed performance control of switched MIMO uncertain nonlinear systems subject to unmodeled dynamics and input nonlinearities

    , Article International Journal of Robust and Nonlinear Control ; Volume 28, Issue 18 , 2018 , Pages 5981-5996 ; 10498923 (ISSN) Malek, S. A ; Shahrokhi, M ; Vafa, E ; Moradvandi, A ; Sharif University of Technology
    In this paper, the design of an adaptive tracking control for a class of switched uncertain multiple-input–multiple-output nonlinear systems in the strict-feedback form with unmodeled dynamics in the presence of three types of input nonlinearity under arbitrary switching has been addressed. By means of an intelligent approximator like a fuzzy logic system or a neural network, the unknown dynamics are estimated. The unmodeled dynamics have been tackled with a dynamic signal. A universal framework for describing different types of input nonlinearity including saturation, backlash, and dead zone has been utilized. By applying the backstepping approach and the common Lyapunov function method,... 

    Design and implementation of a new body weight support (BWS) system

    , Article 5th RSI International Conference on Robotics and Mechatronics, IcRoM 2017, 25 October 2017 through 27 October 2017 ; 2018 , Pages 69-75 ; 9781538657034 (ISBN) Hamidi Rad, M ; Behzadipour, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Gait training is a critical rehabilitation procedure for patients suffering from walking problems. It, however, puts the therapist in high orthopedic risk since he should prevent the patient from possible falling. Body weight support system is a new technology helping such patients and the involved therapist by unloading a percent of the patient's weight. A new over-ground body weight support is introduced in this article. The system is composed of two main modules namely unloading and traction. The unloading module is capable of suspending an individual's weight up to 1000N dynamically. The whole system is attached to an overhead rail, moving over the head of the patient by the traction...