Search for: adaptive-robust-control
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    Introducing an adaptive robust controller for artificial heart

    , Article Proceedings of the IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics, 24 June 2012 through 27 June 2012 ; June , 2012 , Pages 413-418 ; 21551774 (ISSN) ; 9781457711992 (ISBN) Ravanshadi, S ; Jahed, M ; Sharif University of Technology
    Prolonged and uncontrolled high shear stresses and turbulence can cause hemolysis, while alternating and low-level stresses may contribute to platelet activation and thrombus formation. Such deficiencies are reported for Total Artificial Heart (TAH) systems which are generally not fully capable of dynamic adaptation to sudden pressure and volume changes. This study introduces an adaptive robust controller for a linear motor based TAH (LMTAH) which overcomes such shortcomings. Proposed controller performance is compared with simulated natural heart in normal and stressed physiological conditions. Application of adaptive robust control results in flows with less stress variation and... 

    Robust control of LVAD based on the sub-regional modeling of the heart

    , Article Scientia Iranica ; Volume 23, Issue 6 , 2016 , Pages 2934-2943 ; 10263098 (ISSN) Ravanshadi, S ; Jahed, M ; Sharif University of Technology
    Sharif University of Technology  2016
    Left Ventricular Assist Devices (LVAD) have received renewed interest as a bridge-to-transplantation as well as a bridge-to-recovery device. Ironically, reports of malfunction and complications have hindered the growth of this device. In particular, the main concern is LVAD's susceptibility to excessive backlash and suction as a result of ows that are either too low or high, respectively. This study utilizes a well-established physiological model of the cardiovascular system as a reliable platform to study a proposed adaptive robust controller for a rotary motor based LVAD which overcomes such shortcomings. Proposed controller performance is evaluated by comparing simulated natural heart... 

    Design, Fabrication and Model-based Control of Brachiation Robot

    , M.Sc. Thesis Sharif University of Technology Hosseini Lavasani, Mohammad (Author) ; Meghdari, Ali (Supervisor)
    In the beginning of the 90’s a new type of robot was introduced by Fukuda. The brachiation is a type of mobile robot that moves from branch to branch like a long-armed ape. Here, as a new innovation, optimal control is used to obtain the optimal trajectories for two different problems. The first problem is “Brachiation between fixed branches with different distance and height” and the second is “Brachiating and catching the moving target branch”. Theoretical results show that the control effort in the proposed method is reduced by 25% in comparison with the “Target Dynamics” method which was proposed in prior articles for this robot. The obtained optimal trajectory also minimizes the... 

    Adaptive-Robust Control of Dynamic Systems Using Orthonormal Filters

    , M.Sc. Thesis Sharif University of Technology Hoshyar, Mohsen (Author) ; sadati, Nasser (Supervisor)
    In this research, using orthonormal filters, an adaptive-robust controller is designed for a class of SISO dynamic systems for which the input and output datas are available. First, Laguerre filters are combined with orthonormal Chebyshev functions to increase the capability of Laguerre filters in identification of systems with unknown dynamics. Then, the resulted Lagueree-Chebyshev structure is used for closed loop identification of the system and controller is designed. Moreover, RBF neural networks are used to approximate some nonlinear terms appearing in the controller design process.
    Finally, in order to minimize the control effort, a new approach is proposed that leads to a set... 

    Adaptive Control of Semi-Submersible AUV with Uncertainty in Dynamic and Hydrodynamic Parameters

    , M.Sc. Thesis Sharif University of Technology Rahmani, Sobhan (Author) ; Salarieh, Hassan (Supervisor) ; Nejat Pishkenari, Hossein (Supervisor)
    Due to the importance of recognizing the underwater and the existence of danger to human life in this environment, the use of AUVs has greatly expanded. To build and use these vehicles, we need to model dynamic behavior, and control these systems. The nonlinear dynamics of the AUV makes it difficult to use common linear controllers. On the other hand, the coefficients used in dynamic equations have uncertainty and changes, and as a result, dynamic analysis may be probably un-accurate. If the controller is designed, the controller must be self-tuning and robust to be able to withstand changes and uncertainty. Adaptive control is an approach for controlling such systems. The main idea in... 

    Design and performance analysis of a transparent force control strategy for an exoskeleton

    , Article International Conference on Robotics and Mechatronics, ICROM 2015, 7 October 2015 through 9 October 2015 ; 2015 , Pages 563-568 ; 9781467372343 (ISBN) Rashidi, A ; Zibafar, A ; Khezrian, R ; Vossoughi, G ; Sharif University of Technology
    Exoskeleton robots are developed for human rehabilitation and power augmentation. Human and robot interaction is an important issue involved with these robots. In this paper, the interaction force reduction is considered leading to the transparency of a lower limb exoskeleton during swing phase of walking. Achieving this goal, a robust Lyapunov based motion control method has been developed. The desired reference signals for motion control are generated using a direct force control approach. Robot accelerations are estimated by an observer to be employed in the control loop. An adaptation procedure has been proposed for the bound estimation of uncertainties. As part of assumptions, the... 

    Adaptive robust control of fractional-order swarm systems in the presence of model uncertainties and external disturbances

    , Article IET Control Theory and Applications ; Volume 12, Issue 7 , 2018 , Pages 961-969 ; 17518644 (ISSN) Naderi Soorki, M ; Tavazoei, M. S ; Sharif University of Technology
    Institution of Engineering and Technology  2018
    This study investigates the asymptotic swarm stabilisation of fractional-order swarm systems in the presence of two different kinds of model uncertainties and external disturbances while the upper bound of the uncertainties is a linear function of pseudo-states norms with unknown coefficients. To this end, first a fractional-integral sliding manifold is constructed and then an adaptive-robust sliding mode controller is designed to guarantee the asymptotic swarm stability in a fractional-order linear time-invariant swarm system. The stability analysis of the proposed control system is done based on the Lyapunov stability theorem. Using the proposed controller, the coefficients of the upper... 

    Adaptive robust control of robot manipulators subject to input-dependent uncertainties

    , Article 2009 4th IEEE Conference on Industrial Electronics and Applications, ICIEA 2009, Xi'an, 25 May 2009 through 27 May 2009 ; 2009 , Pages 3428-3433 ; 9781424428007 (ISBN) Effatnejad, K ; Namvar, M ; Sharif University of Technology
    In most approaches to adaptive robust control design for manipulators, a constant upper bound is considered for unmodeled dynamics. However, experiments show that the nature of the control input affects the magnitude of the unmodeled dynamics. For example, in an almost rigid manipulator where the mechanical flexibilities are considered as unmodeled dynamics, high frequency components of the input torque which are resulted form non-smooth control laws, can themselves excite system flexibilities. In this paper, we consider different characterizations of the unmodeled dynamics to take into account the effect of control input signal on the unmodeled dynamics. Simulation results illustrate the... 

    Adaptive Robust Control of Floating Offshore Wind Turbines

    , M.Sc. Thesis Sharif University of Technology Izanloo, Mohammad (Author) ; Sadati, Nasser (Supervisor)
    Nowadays, modern life needs energy resources. In the last few centuries, countries have focused on the use of fossil fuels. However, excessive use of fossil fuels, such as oil and coal, has resulted in enormous environmental hazards. Global warming and air pollution are the most visible manifestations of these hazards. In recent years, energy researchers have been looking for alternative sources. The result of this approach is to pay attention to clean and renewable resources such as wind energy.Wind turbines are used to generate electrical energy out of wind. Among the different types, floating offshore wind turbines have been mostly considered because of various benefits. However, they...