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Doktora Tezleri

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Browsing Doktora Tezleri by Subject "Adaptive control systems"

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    Doctoral Thesis
    Control of redundant robot manipulators with telerobotic applications
    (Izmir Institute of Technology, 2016-11) Çetin, Kamil; Tatlıcıoğlu, Enver
    This thesis focuses on task-space control of kinematically redundant robot manipulators with telerobotic applications. The first aim is to design asymptotically stable sub-task controllers for kinematically redundant robot manipulators subject to parametric uncertainties in their dynamics. Initially, a novel combined analysis of the task-space tracking and sub-task controllers is performed for redundant robots having only one extra degree of freedom. Next, an extended task-space controller is designed by integrating manipulator Jacobian with the sub-task Jacobian. Both controllers ensure task-space tracking and sub-task objectives at the amount of redundant degree of freedom. As the second aim, two robust control methods are proposed for task-space tracking of robot manipulators. First, a novel continuous robust controller is designed despite dynamic model and Jacobian uncertainties to ensure asymptotic task-space tracking while requiring measurements of joint positions and velocities. Then, a robust output feedback controller is proposed to ensure ultimately bounded task-space tracking requiring neither measurements of joint positions or velocities nor accurate knowledge of kinematic and dynamic models. The third aim is to develop a passive decomposition method for task-space control of bilateral teleoperation systems. The proposed method ensures coordination of master and slave robots while achieving a desired overall motion for the bilateral teleoperation system. The proposed method is firstly considered for teleoperation systems consisting of kinematically similar master and slave robots, then extended to be applicable to kinematically redundant teleoperation systems. Simulation and experimental studies are performed to present the viability of the proposed methods.
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    Doctoral Thesis
    Online time delay identification and adaptive control for general classes of nonlinear systems
    (Izmir Institute of Technology, 2013) Bayrak, Alper; Tatlıcıoğlu, Enver
    In this dissertation, online identification of time delays is discussed. Specifically, a novel online time delay identification algorithm for nonlinear systems is presented. As a novel departure from the existing literature, in the design of the time delay identification algorithm, time delays are considered as nonlinear parameters effecting the system and nonlinear parameter estimation techniques are adopted. The presented time delay iden~ tification technique is based on a min-max optimization algorithm. The stability of the proposed time delay identification algorithm is investigated via Lyapunov-based stability analysis techniques. It is shown that the developed estimator identifies unknown time delays, upon satisfaction of a nonlinear persistent excitation condition, within a desireq precision that may be adjusted to be very small. The proposed time delay identification method is then modified to be applicable for sig~ nal processing applications. Afterwards, the control of nonlinear systems subject to state delays is considered. The control objective is to ensure output tracking of a time-varying reference trajectory while identifying unknown state delays. Two cases are considered~ First, only the state delays are assumed to be unknown in the nonlinear system dynamics, Second, linear parameters in the system dynamics are assumed to be unknown along witll unknown time delays. To meet the control objectives, the proposed time delay identifica~ tion technique is fused with a control algorithm, and in both cases, both identification anq control objectives are ensured.