Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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  • Master Thesis
    Design, Development, Modeling and Control of a Stewart Platform
    (Izmir Institute of Technology, 2020) Gündüz, Ali Bars; Tatlıcıoğlu, Enver
    Need for a six degrees of freedom test platform to be used in the inertial stabilization development tests of turrets, remote controlled weapon systems or sight systems is present in modern military technology development. To address this research issue, within this thesis study, a Stewart platform is built and is used for stabilization development tests of a sight system. To give a clear picture of the whole system, mechanical design criterion, electrical architecture, communication between system units and chosen hardware of the designed Stewart platform are presented in detail. After the design and development phases are completed, kinematic model is obtained via utilizing the computer–aided design model of the Stewart platform. The inverse kinematic expressions of the platform are made use of to calculate the required actuator behaviors for the platform to achieve the desired motion. Then, a cascade control structure is designed for control of both speed and position of the actuators where proportional integral controller is preferred. The designed control strategy is implemented to the Stewart platform where satisfactory performance is observed for it to be used in military vehicles.
  • Master Thesis
    Periodic Disturbance Estimation Based Robust Control of Marine Vehicles
    (Izmir Institute of Technology, 2020) Kurtoğlu, Deniz; Tatlıcıoğlu, Enver
    Highly uncertain and complex structures of marine vehicles render the control problem a challenging task. Moreover, the problem becomes much more challenging when the system is exposed to environmental disturbances. This thesis tackles this control problem with an adaptive robust control algorithm which is fused with a periodic disturbance estimation method. The periodic disturbance estimation method inspired from a Fourier series expansion technique is applied for compensation of environmental forces. In the first part of the thesis, an adaptive full state feedback backstepping controller which is supported with the periodic disturbance estimation method is applied. Stability of the closed–loop system and the convergence of the tracking error are established via Lyapunov based methods. Simulation studies are provided to support the theoretical results and to demonstrate the effectiveness of the proposed method. In the second part of the thesis, a nonlinear model free observer based adaptive output feedback controller in conjunction with the periodic disturbance estimator is designed. Lyapunov based arguments have been utilized to prove the stability of the closed– loop system, and the convergence of the tracking and observer errors under the closed– loop operation. Performance and viability of the proposed method are demonstrated via numerical simulations.
  • Master Thesis
    On Improving the Performance of Repetitive Leaning Controllers
    (Izmir Institute of Technology, 2019) Çobanoğlu, Necati; Tatlıcıoğlu, Enver
    Robot manipulators are widely used to perform pre–defined tasks repetitively. Nearly all of the mass production factories use the robot manipulators to perform specific operations over and over again. In such a system, the control design may contain some difficulties, unavailabilities and/or there would be additive disturbances due to the periodic motion. Moreover, cost reduction may be vital, hence sensor usage has to be reduced. In the first part of this thesis, to address those restrictions, a model free full state feedback repetitive learning controller which is fused with a one–layer neural network is proposed for robot manipulator which performs a periodic motion. Stability of the system is ensured via Lyapunov based techniques. Numerical simulations and experimental results are introduced to demonstrate the performance of the proposed controller. In the second part of the thesis, under the additional constraint that velocity measurements being unavailable, output feedback repetitive learning controller fused with a neural network term is investigated. The dynamic model of the robot manipulator is again considered as uncertain to avoid its usage as part of the control design, and the reference position vector is still considered to be periodic. The stability of the closed loop system is investigated via Lyapunov based techniques. Numerical simulations are added to demonstrate the proposed controller performance.
  • Master Thesis
    Compliance Control of Shad Redundant Robot
    (Izmir Institute of Technology, 2018) Kanık, Mert; Dede, Mehmet İsmet Can; Tatlıcıoğlu, Enver
    SHAD robot, which is located in IYTE Robotics Laboratory, is designed as a 4 degrees-of-freedom manipulator which has a PRRR serial kinematic structure. The prismatic joint works along the vertical axis, and the revolute joints rotate about the vertical axis. Although the positioning task on the plane can be executed by two revolute joints, SHAD robot is designed to be kinematically redundant using three revolute joints. SHAD name is the abbreviations for SHoulder Haptic Device. The manipulator is constructed by using industrial servomotors coupled with high reduction ratio gears. Hence, this robot can only be used as a haptic device if admittance control is implemented for its control scheme. Accordingly, the aim of this study is to implement and test the admittance control algorithm on SHAD robot. However, since a human operator uses this haptic device when he/she is placed inside the workspace, certain safety precautions should be implemented. Therefore, initially, exploiting the kinematic redundancy of SHAD robot, an obstacle avoidance algorithm to move the robot’s links away from the human operator is implemented and tested in simulations and experiments. To do this; (1) SHAD’s mathematical model is derived, (2) This model is verified, and obstacle avoidance algorithm is validated by simulation tests in MATLAB/Simulink, (3) SHAD robot’s experimental setup is developed, (4) Experimental tests for obstacle avoidance are conducted. After the obstacle avoidance algorithm is implemented in the control of SHAD and proven that it works, admittance control experiments are carried out on human subjects to investigate the effects of the admittance term parameters, mass and damper, on certain performance metrics of the user. It is deduced that; (1) as the mass parameter of the admittance term is increased, accuracy of the operation is decreased while the total effort of the user is increased, (2) as the damper parameter of the admittance term is increased, both the accuracy of the operation and the total effort of the user are increased, (3) when the same corner frequency with different admittance term parameters are used, the accuracy of the operation is almost the same but total effort increases as the parameters increase.
  • Master Thesis
    Learning Control of Robot Manipulators With Telerobotic Applications
    (Izmir Institute of Technology, 2016) Doğan, Kadriye Merve; Tatlıcıoğlu, Enver
    Learning control of teleoperation systems that can be utilized in telerehabilition applications is investigated in this thesis. Specifically, considering the fact that in rehabilitation the patient is required to perform a task over and over again, learning controllers are considered as the most feasible solution, in which desired trajectories are periodic with a known period. Since control of teleoperation systems are directly related with the control of robots that are included to the system, learning control of joint space and task space of these robots are simulated in the first part of this study. Joint space learning controller is designed under the restrictions that the robot dynamic model being uncertain and that joint velocities are unmeasurable. Then, a task–space learning controller is designed by considering the fact that the most desired tasks are defined in the end–effector space. Via Lyapunov based stability analysis methods, asymptotic tracking is ensured for both controllers. Numerical simulation results and experimental studies are utilized to illustrate the performance of the designed controllers. In the second part of this thesis, performance of the direct teleoperation and model mediated teleoperation methods under time delays in the communication cahannel are examined in a comparative manner. In direct teleoperation, the information between master and slave systems are exchanged directly, while the model of the environment of the slave system is learnt and integrated at the master side as proxy dynamics in model mediated teleoperation. Experimental studies are realized to evaluate the performance of both of mentioned methods.
  • Master Thesis
    Compensator design for twin rotor systems
    (Izmir Institute of Technology, 2015) Deniz, Meryem; Tatlıcıoğlu, Enver
    In this thesis study, modeling and control of the in-house developed twin rotor systems are aimed. Firstly, two input-output models are obtained by using experimentally collected data. One model is obtained as transfer functions in the Laplace domain while the other is a neural network based model. Nextly, lag and lead type compensators are designed and then experimentally verified on the twin rotor system. Specifically, first, lag and lag-lag compensators are designed to obtain a reduced steady state error when compared with proportional controllers. Secondly, lead compensation is discussed to obtain a reduced overshoot. Finally, to make use of their favorable properties at the same time, lag-lead compensators are designed. All the compensators are applied to the twin rotor system in our laboratory.
  • Master Thesis
    Design of Nonlinear Observer for Chaotic Message Transmission
    (Izmir Institute of Technology, 2014) Çobanlar, Muhammed; Tatlıcıoğlu, Enver
    Chaos is an interesting nonlinear phenomena that occurs in wide variety of fields. A significant amount of research was devoted to understanding chaos and its properties. After that, researchers focused on searching for possible application areas for chaos to utilize its properties. The need to increase the security of a communication system is considered as a perfect match for chaos and its several properties, yielding chaotic communication. In this thesis, chaotic communication is approached from a control theory perspective. Specifically, three nonlinear observers are designed to extract message encrypted in a chaotic communication signal. The design and stability analysis is presented for the first observer, and the other observers are presented as modifications to the first one. Extensive numerical simulations are performed to demonstrate the viability of the proposed observers. Robustness of the observers to noise, additive disturbances, and parametric mismatch, and security of the observers are demonstrated numerically.
  • Master Thesis
    Modelling and Control of Hypersonic Aircraft Vehicles
    (Izmir Institute of Technology, 2012) Bıdıklı, Barış; Tatlıcıoğlu, Enver
    The increasing number of works on hypersonics and the recent interest of Ministry of Defense on developing a hypersonic missile are amongst the main motivations behind this thesis. Research on hypersonics seems to divide into two main categories: deriving dynamic models for HSVs and designing model-based controllers. Initially, we decided to investigate the control problems associated with HSVs. However, due to the restrictions imposed by the leading sponsors of hypersonic research (such as NASA, US AF, US DoD, DARPA, etc), researchers did neither publish nor share the model parameters for HSVs. As a result, our initial focus was deriving a dynamic model for an HSV. Firstly, modelling approaches for HSVs and we noticed that it is extremely hard to directly obtain the HSV dynamic model parameters. In addition to this, the HSV nonlinear dynamic model which was commonly mentioned in the literature is not related to the control inputs directly. As a result, the linearized HSV dynamic models were investigated, and the linear parameter varying model was derived. Next, control problems associated with the HSVs are investigated. Due to the highly complicated and time-varying nature of their dynamics, designing a robust control law is aimed. The main reason behind choosing to design a robust control law was that the robust controllers usually require minimum knowledge about the HSV dynamics. The stability of the proposed robust control law is then investigated via Lyapunov-based techniques and the tracking error is driven to the origin exponentially fast by using designed controller.