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#### 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...

#### The contrastive study of identical and generalized synchronization

, Article International Conference on Control, Automation and Systems, ICCAS 2007, Seoul, 17 October 2007 through 20 October 2007 ; December , 2007 , Pages 1573-1576 ; 8995003871 (ISBN); 9788995003879 (ISBN) ; Haeri, M ; Sharif University of Technology
2007

Abstract

The main purpose of this study is to compare identical synchronization and linear generalized synchronization from various points of views including synchronization error variance, convergence time, control effort variance, maximum and minimum values of the control signal. The nonlinear control is used in the both synchronizations. The results of our study show that the identical synchronization is not the optimal one from the mentioned criteria points of view. © ICROS

#### Robust adaptive backstepping control of uncertain lorenz system [electronic resource]

, Article Journal of American Institute of Physics ; 2010, Vol. 20, pp. 1-5 ; Jalili, Nader ; Mahboobi, Seyed Hanif ; Alasty, Aria ; Meghdari, Ali ; Sharif University of Technology
Abstract

In this paper, a novel robust adaptive control method is proposed for controlling the Lorenz chaotic attractor. A new backstepping controller for the Lorenz system based on the Lyapunov stability theorem is proposed to overcome the singularity problem that appeared in using the typical backstepping control method. By exploiting the property of the system, the resulting controller is shown to be singularity free and the closed loop system is globally stable. Due to unavailability of system states measurement in practice, the controller is selected such that only one system state is needed. To overcome the problem of parameter uncertainty, an additional term to Lyapunov function is added and...

#### 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, IMECE 2007, Seattle, WA, 11 November 2007 through 15 November 2007 ; Volume 11 PART A , 2008 , Pages 201-208 ; 079184305X (ISBN); 9780791843055 (ISBN) ; Salaried, H ; Alasty, A ; Sharif University of Technology
2008

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...

#### An adaptive unscented Kalman filter for quaternion-based orientation estimation in low-cost AHRS

, Article Aircraft Engineering and Aerospace Technology ; 2007 , Pages 485-493 ; 00022667 (ISSN) ; Volume 79, Issue 5 ; Ghanbarpour Asl, H ; Sharif University of Technology
2007

Abstract

Purpose - This paper aims to develop an adaptive unscented Kalman filter (AUKF) formulation for orientation estimation of aircraft and UAV utilizing low-cost attitude and heading reference systems (AHRS). Design/methodology/approach - A recursive least-square algorithm with exponential age weighting in time is utilized for estimation of the unknown inputs. The proposed AUKF tunes its measurement covariance to yield optimal performance. Owing to nonlinear nature of the dynamic model as well as the measurement equations, an unscented Kalman filter (UKF) is chosen against the extended Kalman filter, due to its better performance characteristics. The unscented transformation of the UKF is shown...

#### Effects of rotary inertia and shear deformation on nonlinear vibration of micro/nano-beam resonators

, Article 2005 ASME International Mecahnical Engineering Congress and Exposition, IMECE 2005, Orlando, FL, 5 November 2005 through 11 November 2005 ; Volume 7 MEMS , 2005 , Pages 439-445 ; 1096665X (ISSN); 079184224X (ISBN); 9780791842249 (ISBN) ; Alasty, A ; ASME Micro Electro Mecahnical Systems Division ; Sharif University of Technology
2005

Abstract

In this paper, the large amplitude tree vibration of a doubly clamped microbeam is considered. The effects of shear deformation and rotary inertia on the large amplitude vibration of the microbeam are investigated. To this end, first Hamilton's principle is used in deriving the partial differential equation of the microbeam response under the mentioned conditions. Then, implementing the Galerkin's method the partial differential equation is converted to an ordinary nonlinear differential equation. Finally, the method of multiple scales is used to determine a second order perturbation solution for the obtained ODE. The results show that nonlinearity acts in the direction of increasing the...

#### Nonlinear optimal control of two-level large-scale systems; Part I - Interaction prediction 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) ; Momeni, A. R ; Sharif University of Technology
IEEE Computer Society
2005

Abstract

In this paper, which consists of two parts, a new two-level computational algorithm is used for nonlinear optimal control of large-scale systems. The two-level optimizer uses a new coordination strategy which is based on the gradient of interaction errors instead of the gradient of overall performance function. The advantages of the new method can be categorized into two parts: First, the new formulation is applicable to a large class of problems whilst the classical model coordination method is not. Second, it extremely reduces the number of iterations required for obtaining the overall optimal solution. Although the computational burden of the algorithm in the first level increases...

#### Hybrid stepper motor backstepping control in micro-step operation

, Article 2005 ASME International Mechanical Engineering Congress and Exposition, IMECE 2005, Orlando, 5 November 2005 through 11 November 2005 ; Volume 118 B, Issue 2 , 2005 , Pages 993-997 ; Alasty, A ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2005

Abstract

A nonlinear position controller based on backstepping control technique is proposed for a hybrid stepper motor in micro-step operation. Backstepping control approach is adapted to derive the control scheme, which is robust to parameter uncertainties and external load disturbance. Simulation results clearly show that the proposed controller can track the position reference signal successfully under parameter uncertainties and load torque disturbance rejection. Copyright © 2005 by ASME

#### 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) ; Beik, H. Z ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2003

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, 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

#### Sliding mode control of electromagnetic system based on fuzzy clustering estimation (an experimental study)

, Article Proceedings of the 7th Biennial Conference on Engineering Systems Design and Analysis ; Volume 1 , 2004 , Pages 843-850 ; ISBN: 0791841731 ; ISBN: 9780791841730 ; Salarieh, H ; Shabani, R ; Sharif University of Technology
Abstract

Using the combination of fuzzy clustering estimation and sliding mode control, a technique for controlling the magnetic levitation (ML) systems is introduced. This technique is applied to an experimental setup of an ML system for investigating the method derived. The system considered, is a symmetric rotor supported by a cantilever load cell beam and excited by only one electromagnet of a 4-pole magnetic bearing setup. After demonstrating the experimental setup instruction and the specifications of its parts, the clustering, and the sliding mode control methods are explained briefly, then the quality of implementing the techniques to the setup is described step by step. Finally, the results...

#### Frequency response calculation of non-linear torsional vibration in gear systems

, Article Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics ; Volume 222, Issue 1 , 2008 , Pages 49-60 ; 14644193 (ISSN) ; Moeenfard, H ; Rafsanjani, A ; Sharif University of Technology
2008

Abstract

The current paper focuses on the non-linear torsional vibration of a one-stage transmission gear system. Four different methods have been applied for solution of the equation of motion; the discretization method, the perturbation method, the Ritz method, and the stepwise time integration of the equation of motion. The time and frequency results from these analyses have been compared with each other, as well as those reported in literatures. Although all of these methods are accurate and computationally effective for finding the main spectral contribution, however, only the discretization method and the step-wise time-integration model are able to identify the other frequency components. ©...

#### 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...

#### Robust tracking control of attitude satellite with using new SMC and EKF for large maneuvers

, Article 2006 IEEE Aerospace Conference, Big Sky, MT, 4 March 2006 through 11 March 2006 ; Volume 2006 , 2006 ; 1095323X (ISSN); 0780395468 (ISBN); 9780780395466 (ISBN) ; Sadati, N ; Momeni, H ; Sharif University of Technology
2006

Abstract

Control1,2 of a class of uncertain nonlinear systems which estimates unavailable state variables is considered. A new approach for robust tracking control problem of satellite for large rotational maneuvers is presented in this paper. The features of this approach include -a strong algorithm to estimate attitude, based on discrete extended kalman filter combined with a continuous extended kalman filter and attitude nonlinear model -a robust controller based on sliding-mode with perturbation estimation. The estimation result of interval kalman filtering is a sequence of interval estimates that encompasses all possible optimal attitude estimates, which the interval system may generate. The...

#### Elastoplastic stress study in thick-walled spherical vessels considering finite deformation

, 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) ; Shamsaei, N ; Naghdabadi, R ; Danesh Sararoudi, M ; Sharif University of Technology
2006

Abstract

An exact elasto-plastic analytical solution for large-strained internal pressurized thick-walled spherical vessels made of elastic-linear and nonlinear hardening material is derived in this paper. This solution is based on the notion of finite strains, the deformation theory of Hencky and the yield criteria of von Mises and Tresca. Nolinear elastic solution of an axisymetric boundary value problem is used as a basis to generate its inelastic solution, whereas the Hyper-elastic constitutive equation is invoked to represent the material response in the elastic region. This method treats the material parameters as field variables. Their distributions are obtained in an iterative manner using...

#### Stochastic analysis of two dimensional nonlinear panels with structural damping under random excitation

, Article Aerospace Science and Technology ; Volume 10, Issue 3 , 2006 , Pages 192-198 ; 12709638 (ISSN) ; Pourtakdoust, S. H ; Assadian, N ; Sharif University of Technology
2006

Abstract

Stochastic behavior of panels in supersonic flow is investigated to assess the significance of including the damping caused by the strains resulting from axial extension of the panel. The governing equations of motion are based on the Von Karman's large deflection equation and are considered with Kelvin's model of structural damping. The panel under study is two dimensional and simply supported for which the first order piston theory is used to account for the unsteady aerodynamic loading. Transformation of the governing partial differential equation to a set of ordinary differential equations is performed through the Galerkin averaging technique. The statistical response moment equations...

#### 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...

#### Extended dynamic matrix control design for a DC-DC power converter

, Article 37th Southeastern Symposium on System Theory, SST05, Tuskegee, AL, 20 March 2004 through 22 March 2004 ; Volume 37 , 2005 , Pages 191-195 ; Sharif University of Technology
2005

Abstract

EDMC is an extended version of the dynamic matrix control (DMC) approach to control nonlinear processes. In this method, control input is determined based on linear model approximation of the process in each control/optimization interval. The difference between linear and nonlinear models of the process is considered as the known part of the feedback signal in DMC control formulation. Usually the fixed point or the secant method is applied to reduce the difference between two models. In this paper, an EDMC controller is designed for a DC-DC power converter of the boost type. The behavior of the scheme is discussed with the transient and steady state response to step and sinusoidal...

#### Identification and adaptive control of the uncertain lorenz system

, Article 2005 ASME International Mechanical Engineering Congress and Exposition, IMECE 2005, Orlando, FL, 5 November 2005 through 11 November 2005 ; Volume 74 DSC, Issue 2 PART B , 2005 , Pages 1105-1111 ; 0791842169 (ISBN); 9780791842164 (ISBN) ; Shahrokhi, M ; Sharif University of Technology
2005

Abstract

In this paper an identification method which can estimate the unknown parameters of a general nonlinear system based on three techniques (gradient, least-squares and rapid identification) has been developed. The stability of the proposed schemes has been shown using the Lyapunov stability theorem. The properties of each identification technique have been discussed briefly. Open loop identification of the Lorenz chaotic system is presented to show the effectiveness of the proposed approach. To illustrate the efficiency of the identification method for control purposes, it has been applied for controlling the well-known Lorenz system. By exploiting the property of the system a novel...

#### 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