Master Degree / Yüksek Lisans Tezleri

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

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COAR Access Rights: search.filters.coarAccessRights.open accessSubject: search.filters.subject.Obstacle avoidance

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  • 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
    Redundant Mobile Robort Control
    (Izmir Institute of Technology, 2016) Çelik, Onur; Dede, Mehmet İsmet Can
    Indoor mobile robots are one of the widely researched and developing technologies in robotic field since they can be used in the service robotics and industrial application domains. Moreover, a sub-category of mobile robots, omnidirectional mobile robots, allow performing tasks in narrow indoor spaces by providing better motion capabilities. Additionally, redundancy in mobile robots is started to be used for various advantages including fault tolerance and increased payloads. The objective of this thesis is to improve the design of the omnidirectional mobile robot that was previously constructed in IRL (IzTech Robotics Lab) and develop a redundancy resolution algorithm in order to control the redundant omnidirectional mobile robot to tolerate faults in the actuation system. Initially, the mechanical structure of the mobile robot is improved by the addition of a suspension system for each wheel assembly. A new onboard controller hardware is used and a new top-level controller is employed to be used along the redundancy resolution algorithm. Additionally, previously developed obstacle avoidance algorithm is improved by employing a new configuration of sensors and including a virtual damper to compensate for variable velocity level while approaching to an obstacle. The fault tolerance algorithm is developed in this thesis by integrating a pseudo inverse of the Jacobian matrix that is subjected to a virtual weighted matrix so that the motion of the mobile robot will sustain its motion even though there is an efficiency drop in one of the actuators. Top-level control algorithm along with the fault tolerance and the obstacle avoidance algorithms is experimentally tested and test results indicate that the mobile robot can achieve the primary task in the case of one of the actuator’s efficiency drops down to 70% or in the case of multiple obstacles on the path of the robot.