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disturbance-observer
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Control of Three-phase UPS with Nonlinear Load Using Disturbance Observer Considering Transformer Concerns
, M.Sc. Thesis Sharif University of Technology ; Tahami, Farzad (Supervisor)
Abstract
Nowadays, non-linear loads comprise an important part of electrical grids. One of the most essential sources of nonlinear loads is switching power supplies, which mainly include power electronic rectifiers. When power outage occurs, Uninterruptible Power Supplies (UPS) must be able to supply these loads. The nonlinearity of the load has a significant effect on the Total Harmonic Distortion (THD) of the output voltage, which may not be easily reduced, especially in three-phase inverters. Furthermore, the presence of isolating transformers in these power supplies limits the control of harmonics and intensifies the nonlinear effects of the system.In this Master Thesis, a disturbance observer is...
Boundary control of a vertical nonlinear flexible manipulator considering disturbance observer and deflection constraint with torque and boundary force feedback signals
, Article International Journal of Systems Science ; 2021 ; 00207721 (ISSN) ; Najafi Ardekany, A ; Alasty, A ; Sharif University of Technology
Taylor and Francis Ltd
2021
Abstract
In this paper, boundary control (BC) laws are designed to find a BC solution for a single-link nonlinear vertical manipulator to suppress the link’s transverse vibrations and control the rigid body nonlinear large rotating motion. The governing equations of motions and boundary conditions, which all consist of a set of PDEs and ODEs have been derived based on the Hamilton principle. It is desired to regulate large angular orientation, suppress the flexible link’s transverse vibrations and compensate the boundary disturbance simultaneously. The amount of elastic boundary vibration has remained within the constraint range. By considering novel Barrier-Integral Lyapunov functional in order to...
Finite time control of robotic manipulators with position output feedback
, Article International Journal of Robust and Nonlinear Control ; Volume 27, Issue 16 , 2017 , Pages 2982-2999 ; 10498923 (ISSN) ; Moravej Khorasani, M ; Haeri, M ; Sharif University of Technology
Abstract
This paper deals with the robust finite time tracking of desired trajectories for a wide group of robotic manipulators in spite of unknown disturbances, uncertainties, and saturations of actuators while only manipulator's positions are available and its velocities are not measurable physically. A new form of chattering-free second order fast nonsingular terminal sliding mode control scheme is introduced to design input torques for fulfilling the determined tracking objective in the adjustable total finite settling time. The proposed control algorithm is incorporated with two nonlinear observers to estimate disturbances and velocities of joints within finite settling times. The global finite...
Reducing Harmonic Distortion in Three-phase Parallel UPS Configuration with Nonlinear Load Using Disturbance Observer
, M.Sc. Thesis Sharif University of Technology ; Tahami, Farzad (Supervisor)
Abstract
Three-phase inverters as a UPS are very common in industry and non-linear loads such as rectifiers are growing in industry. Three phase inverter with non-linear load can lead to highly distorted output voltage which can make problem for sensitive loads such as servers etc. Parallel configuration of three-phase inverters, also have the same problem with non-linear loads. Droop control and Master/slave control methods are two major methods which investigated in this thesis. This paper proposes a method for reducing voltage THD in three phase inverters with non-linear load. The proposed method considers the load current as a disturbance and provide a control strategy to reject it using the...
Reducing output voltage THD of a three-phase inverter with non-linear load using disturbance observer
, Article 8th Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2017, 14 February 2017 through 16 February 2017 ; 2017 , Pages 431-436 ; 9781509057665 (ISBN) ; Tahami, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
Non-linear loads such as rectifiers are growing in industry. Three phase inverter with non-linear load can lead to highly distorted output voltage. This paper proposes a method for reducing voltage THD in three phase inverters with non-linear load. The proposed method considers the load current as a disturbance and provide a control strategy to reject it using the disturbance observer method. This method doesn't need any additional sensors or hardware and is implemented digitally in controller. Simulation results show that the presented method will reduce the total harmonic distortion of the output voltage. © 2017 IEEE
Boundary control of a vertical nonlinear flexible manipulator considering disturbance observer and deflection constraint with torque and boundary force feedback signals
, Article International Journal of Systems Science ; Volume 53, Issue 4 , 2022 , Pages 704-725 ; 00207721 (ISSN) ; Najafi Ardekany, A ; Alasty, A ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
In this paper, boundary control (BC) laws are designed to find a BC solution for a single-link nonlinear vertical manipulator to suppress the link’s transverse vibrations and control the rigid body nonlinear large rotating motion. The governing equations of motions and boundary conditions, which all consist of a set of PDEs and ODEs have been derived based on the Hamilton principle. It is desired to regulate large angular orientation, suppress the flexible link’s transverse vibrations and compensate the boundary disturbance simultaneously. The amount of elastic boundary vibration has remained within the constraint range. By considering novel Barrier-Integral Lyapunov functional in order to...
Intelligent trajectory tracking of an aircraft in the presence of internal and external disturbances
, Article International Journal of Robust and Nonlinear Control ; Volume 29, Issue 16 , 2019 , Pages 5820-5844 ; 10498923 (ISSN) ; Banazadeh, A ; Sharif University of Technology
John Wiley and Sons Ltd
2019
Abstract
This research deals with developing an intelligent trajectory tracking control approach for an aircraft in the presence of internal and external disturbances. Internal disturbances including actuators faults, unmodeled dynamics, and model uncertainties as well as the external disturbances such as wind turbulence significantly affect the performance of the common trajectory tracking control approaches. There are several fault-tolerant control approaches in the literature to overcome the effects of specific actuator or sensor faults during the flight. However, trajectory tracking control of an air vehicle in the presence of unexpected faults and simultaneous presence of wind turbulence is...
A comparison between disturbance observer-based and model-based control of needle in percutaneous applications
, Article IECON Proceedings (Industrial Electronics Conference), 25 October 2012 through 28 October 2012 ; October , 2012 , Pages 2104-2108 ; 9781467324212 (ISBN) ; Jahed, M ; The Institute of Electrical and Electronics Engineers (IEEE); IEEE Industrial Electronics Society (IES) ; Sharif University of Technology
2012
Abstract
In this paper, model-based and distrbance observer (DOB)-based control of needle in precautious applications are compared. In the model-based approach, the force acting on the needle is calculated by evaluating the finite element model (FEM) of the tissue with the tissue deformation. In DOB-based method, the force acting on the needle is considered as an external disturbance and it is estimated using position and velocity of the needle. In both approaches, the calculated/estimated force is used in a sliding mode control scheme to steer the needle to the target. A dynamics equation for the movement of the needle is proposed which includes the force applied by the tissue to the needle. The...
Simultaneous trajectory tracking and aerial manipulation using a multi-stage model predictive control
, Article Aerospace Science and Technology ; Volume 112 , 2021 ; 12709638 (ISSN) ; Banazadeh, A ; Sharif University of Technology
Elsevier Masson s.r.l
2021
Abstract
With the exception of a few works, the current approaches to aerial manipulation control do not typically consider the system constraints in the control design process. Also, the issue of closed-loop stability in the presence of system constraints is not thoroughly analyzed. In this paper, a novel multi-stage model predictive control (MPC)-based approach for aerial manipulation is proposed to ensure the closed-loop stability in the presence of model uncertainties and external disturbances, while satisfying the operational constraints. The detailed nonlinear model of a general aerial manipulator, consisting of a quadrotor equipped with a 3 degrees of freedom manipulator, is first developed...