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Aircraft Drag Determination in Frequency Domain Using Parametric Identification Methods
, M.Sc. Thesis Sharif University of Technology ; Banazadeh, Afshin (Supervisor)
Abstract
Determination of drag force is one of the most difficult activities in the design and development of an aircraft. Accurate estimation of drag force is very important in design studies and needs to be estimated over and over during the design trade-offs. Importance of the determination of drag force, from the performance viewpoint, is an important stage in development and evaluation of an aircraft behavior and if the thrust and drag forces are well determined, the other performance characteristics could be easily estimated. Different methods are introduced for determination of drag using flight test or system identification methods in the time domain owing some limitations, disadvantages or...
Examining and Choosing the Appropriate Control Algorithm and Controller Design for a Ship in Order to Path Following
, M.Sc. Thesis Sharif University of Technology ; Seif, Mohammad Saeed (Supervisor)
Abstract
In this research, it has been tried to design two controllers for a KVLCC2 tanker assuming unknown hydrodynamic characteristics and its mathematical model in order to maintain its course and speed. At first, due to the lack of an experimental model of a vessel, a three-degree-of-freedom MMG model of the KVLCC2 vessel was modeled in the SIMULINK, MATLAB, to be used as a basis for other tests and simulations. Therefore, by using the designed three degree of freedom model, all parameters affecting the floating maneuver were examined. In the next section, using the DNV standard, we designed two wind and sea current systems for system input disturbances. And finally, by using dynamic models of...
Frequency domain identification of a tapered beam embedded by piezoelectric layer
, Article 2016 International Conference on Advanced Mechatronic Systems, ICAMechS 2016, 30 November 2016 through 3 December 2016 ; 2017 , Pages 312-317 ; 23250682 (ISSN); 9781509053469 (ISBN) ; Ahranjani, F. F ; Kamankesh, Z ; Sharif University of Technology
IEEE Computer Society
2017
Abstract
This study is conducted aiming to identify the dynamics of a tapered beam, embedded by piezoelectric layer. Narrowing the tip of the beam equipped with piezoelectric patches leads to optimize the output power after excitation by the frequency sweep input. An accelerometer is installed on the beam base, which measures the acceleration that is applied to the system. Piezoelectric sensors also measure the generated voltage. The experimental test data is handled through CIFER software, using Fourier transform and Bode plot in the frequency domain, to obtain appropriate transfer functions. MATLAB is used for nonlinear simulation and validation of discrete transfer functions by a set of data that...
Frequency response analysis for dynamic model identification and control of a ducted fan aerial vehicle in hover
, Article Applied Mechanics and Materials, Neptun-Olimp ; Volume 332 , 2013 , Pages 56-61 ; 16609336 (ISSN) ; 9783037857335 (ISBN) ; Banazadeh, A ; Sharif University of Technology
2013
Abstract
System Identification is a key technology for the development and integration of modern engineering systems including unconventional flying vehicles. These systems are highly parametric with complex dynamics and nonlinearities. Ducted fans are special class of these vehicles that can take off vertically, hover and cruise at very low speed. In this paper, an exact equivalent linear system is found from the non-linear dynamic model of a ducted fan by use of frequency response identification. Here, power spectral density analysis is performed, using CIFER software, to evaluate the input-output responses in hover and to derive the transfer functions based on the coherence criterion. Then,...
Frequency domain identification of the Nomoto model to facilitate Kalman filter estimation and PID heading control of a patrol vessel
, Article Ocean Engineering ; Volume 72 , November , 2013 , Pages 344-355 ; 00298018 (ISSN) ; Ghorbani, M. T ; Sharif University of Technology
2013
Abstract
This paper presents a detailed frequency-domain system identification method applied to identify steering dynamics of a coastal patrol vessel using a data analysis software called CIFER. Advanced features such as the Chirp-Z transform and composite window optimization are used to extract high quality frequency responses. An accurate, robust and linear transfer function model is derived for yaw and roll dynamics of the vessel. To evaluate the accuracy of the identified model, time domain responses from a 45-45 zig-zag test are compared with the responses predicted by the identified model. The identified model shows excellent predictive capability and is well suited for simulation and...
Identification of the equivalent linear dynamics and controller design for an unmanned underwater vehicle
, Article Ocean Engineering ; Volume 139 , 2017 , Pages 152-168 ; 00298018 (ISSN) ; Seif, M. S ; Khodaei, M. J ; Rezaie, M ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
This paper investigates the applicability of frequency-domain system identification technique to achieve the equivalent linear dynamics of an autonomous underwater vehicle for control design purposes. Frequency response analysis is performed on the nonlinear and coupled dynamics of the vehicle, utilizing the CIFER® software to extract a reduced-order model in the form of equivalent transfer functions. Advanced features such as chirp-z transform, composite window optimization, and conditioning are employed to achieve high quality and accurate frequency responses. A particular frequency-sweep input is implemented to the nonlinear simulation model to achieve pole-zero transfer functions for yaw...