Browsing by Author "Korkmaz, Ozan"

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Citation Count: Korkmaz, O., İder, S.K. (2014). Hybrid force and motion control of flexible joint parallel manipulators using inverse dynamics approach. Advanced Robotics, 28(18), 1221-1230. http://dx.doi.org/10.1080/01691864.2014.920719
Hybrid force and motion control of flexible joint parallel manipulators using inverse dynamics approach
(Taylor&Francis Ltd, 2014) Korkmaz, Ozan; İder, Sıtkı Kemal; 108608
An inverse dynamics control algorithm is developed for hybrid motion and contact force trajectory tracking control of flexible joint parallel manipulators. First, an open-tree structure is considered by the disconnection of adequate number of unactuated joints. The loop closure constraint equations are then included. Elimination of the joint reaction forces and the other intermediate variables yield a fourth-order relation between the actuator torques and the end-effector position and contact force variables, showing that the control torques do not have an instantaneous effect on the end-effector contact forces and accelerations because of the flexibility. The proposed control law provides simultaneous and asymptotically stable control of the end-effector contact forces and the motion along the constraint surfaces by utilizing the feedback of positions and velocities of the actuated joints and rotors. A two degree of freedom planar parallel manipulator is considered as an example to illustrate the effectiveness of the method
Citation Count: Ider, Sitki Kemal; Korkmaz, Ozan; Denizli, Mustafa Semih, "On the stability of inverse dynamics control of flexible-joint parallel manipulators in the presence of modeling error and disturbances", Turkish Journal of Electrical Engineering and Computer Sciences, Vol. 27, No. 1, pp. 649-662, (2019).
On the stability of inverse dynamics control of flexible-joint parallel manipulators in the presence of modeling error and disturbances
(Tubitak Scientific & Technical Research Council Turkey, 2019) İder, Sıtkı Kemal; Korkmaz, Ozan; Denizli, Mustafa Semih; 108608
Inverse dynamics control is considered for flexible-joint parallel manipulators in order to obtain a good trajectory tracking performance in the case of modeling error and disturbances. It is known that, in the absence of modeling error and disturbance, inverse dynamics control leads to linear fourth-order error dynamics, which is asymptotically stable if the feedback gains are chosen to make the real part of the eigenvalues of the system negative. However, when there are modeling errors and disturbances, a linear time-varying error dynamics is obtained whose stability is not assured only by keeping the real parts of the frozen-time eigenvalues of the system negative. In this paper, the stability of such systems is investigated and it is proved that the linear time-varying system can be rendered stable by selecting the feedback gains such that the variation of the system becomes sufficiently slow. To illustrate the performance of the control method, deployment motion of a 3-(R) under bar PR planar parallel manipulator subject to impact is simulated. For the impact model, the impulse-momentum and the coefficient of restitution equations for the system are derived.
Citation Count: Korkmaz, O., İder, S.K., Özgçren, M.K. (2016). Trajectory tracking control of an underactuated underwater vehicle redundant manipulator system. Asian Journal Of Control, 18(5), 1593-1607. http://dx.doi.org/10.1002/asjc.1291
Trajectory tracking control of an underactuated underwater vehicle redundant manipulator system
(Wiley-Blackwell, 2016) Korkmaz, Ozan; İder, Sıtkı Kemal; Özgören, M. Kemal; 108608; 7866
The purpose of this study is to control the position of an underactuated underwater vehicle manipulator system (U-UVMS). It is possible to control the end-effector using a regular 6-DOF manipulator despite the undesired displacements of the underactuated vehicle within a certain range. However, in this study an 8-DOF redundant manipulator is used in order to increase the positioning accuracy of the end-effector. The redundancy is resolved according to the criterion of minimal vehicle and joint motions. The underactuated underwater vehicle redundant manipulator system is modeled including the hydrodynamic forces for the manipulator in addition to those for the autonomous underwater vehicle (AUV). The shadowing effects of the bodies on each other are also taken into account when computing the hydrodynamic forces. The Newton-Euler formulation is used to derive the system equations of motion including the thruster dynamics. In order to establish the endeffector trajectory tracking control of the system, an inverse dynamics control law is formulated. The effectiveness of the control law even in the presence of parameter uncertainties and disturbing ocean currents is illustrated by simulations.