The purpose of this thesis is to develop a position control method for parallel manipulators so that the end effector can follow a desired trajectory specified in the task space where joint flexibility that occurs at the actuated joints is also taken into consideration. At the beginning of the study, a flexible joint is modeled, and the equations of motion of the parallel manipulators are derived for both actuator variables and joint variables by using the Lagrange formulation under three assumptions regarding dynamic coupling between the links and the actuators. These equations of motion are transformed to an input/output relation between the actuator torques and the actuated joint variables to achieve the trajectory tracking control. Moreover, the singular configurations of the parallel manipulators are explained. As a case study, a three degree of freedom, two legged planar parallel manipulator is simulated considering joint flexibility. The structural damping of the active joints, viscous friction at the passive joints and the rotor damping are also considered throughout the study. Matlab&reg / and Simulink&reg / softwares are used for the simulations. The results of the simulations reveal that steady state errors are negligibly small and good tracking performances can be achieved.

In this thesis, a technique for the motion of parallel manipulators through drive singularities is investigated. To remedy the problem of unbounded inverse dynamics solution in the neighborhood of drive singularities, an inverse dynamics controller which uses a conventional inverse dynamics control law outside the neighborhood of singularities and switches to the mode based on the formerly derived modified equations inside the neighborhood of singularities is proposed. As a result, good tracking performance is obtained while the actuator forces remain within the saturation limits of the actuators around singular configurations.

In the thesis study, it is intended to design and manufacture an anthropomorphic robot head that can resemble human head/neck and eye movements. The designed robot head consists of a 4-DOF neck and a 4-DOF head. The head is composed of 3-DOF eyes and 1-DOF jaw. This work focuses on the head/neck and eyes therefore / the other free to move parts such as eyebrows, eyelids, ears etc. are not implemented. The general kinematic human modeling technique can be applied to facilitate the humanoid robotics design process since human anatomy can be represented as a sequence of rigid bodies connected by joints. In this study, we refer to the anthropometric data in determining the dimensions of all parts in order to have a robot head as human-like as possible. In addition, motion types, motion ranges and their velocities are considered. These factors are of great importance in imitating the human head movements as close as possible. It is intended that the developed humanoid robot head will be used as a research platform in studying fields such as / social interaction between human and robots, artificial intelligence and virtual reality. It will also be an experimental setup to conduct experiments for studying active vision systems.

In this thesis a modular embedded system for Mechatronics education and research is designed and implemented. Four types of control boards are manufactured and related software is developed at board and PC level. A star like topology is used for boards architecture. One bridge board is responsible for handling communication between the PC and all the other boards that are connected independently to that bridge board. For PC communication Universal Seial Bus (USB), for inter peripheral communication serial peripheral interface (SPI) is used. By the use of USB and SPI, the system becomes scalable and hot pluggable. All these four boards can be used in stand alone and/or together in different applications. The system covers / general analog digital input output, several types of motor control and simple graphical display applications. The firmware and software is developed in a modular, flexible and transparent way allowing users all level accessibility. This way, the application fields and the content of the courses that will be using this system become very versatile. A simulation of hard disk reading experiment is designed and implemented to show the integral capabilities of the system. In this experiment all the boards are utilized and used together. As a result, a system is designed for Mechatronics experiments and research. A modular approach is adopted which is compsed of units that can also work in a stand-alone manner. A software library developed for the PC platform facilitates high-level usage of these cards whereas it is possible to implement custom codes on these boards. To sum up, an affordable, versitale, scalable and transparent system is developed which is specifically tailored for Mechatronics applications.

Virtual Reality (VR) applications in medicine had significant improvements. 3D visualization of various anatomical parts using advanced medical scanner images, anatomy education, surgery operation simulation, virtual simulator for laparoscopic skills, virtual endoscopy, psychotherapy and rehabilitation techniques are some of the VR applications in medicine. Integration of the haptic devices into VR applications increased quality of the systems. By using haptic devices, the user can not only feed information to the computer but can receive information from the computer in the form of a felt sensation on some part of the body. In this thesis a dental education simulator is developed by using a computer, a monitor, a haptic device and stereoscopic devices. The entire jaw model, all teeth and decay is modeled in the virtual environment. It is possible to diagnose the decay and remove the decay region by using different dental instruments developed in the system. Different graphical rendering methods like Marching Cubes, Ray-casting on GPU are implemented and compared. The system is used by dentists from METU Health Center and Ankara University and performance tests are applied to the system. By this system it is expected to develop a more realistic and effective preclinical education. Several advantages offered by the simulator include: an effective learning environment without undue fear of mistakes, facilitation of repetition, provision of opportunities to quantitatively assess student skills, rapid training environment without an instructor and lower the cost of dentist training.

Robotics is an emerging field, and it is also affecting several other fields. Design of robotic platforms gains more importance since the focus and aim of the robotics research broadens widely and the variety of the users is significant. This work aims to present the design of a modular mobile robotic platform, which should be simple, easy to build and easy to use. The concept of modularity, usage of off-the shelf components and utilizing a PC platform, are addressed in this work. As a result of this work, a conceptual design is presented, and a prototype is built to highlight some important aspects of the conceptual design.

The hyper redundant manipulators (HRMs) have excessively large degrees of freedom. As a special but practicable subset, the binary HRMs use binary (on-off) actuators with only two stable states such as pneumatic cylinders and solenoids. Such actuators are simple, cheap, and easy to control. Therefore, a binary HRM has been studied in this thesis. The thesis work covers the conceptual design of a spatial binary HRM together with its controlled motion simulations. The manipulator consists of many modules, each of which has the same constructive characteristics and consists of three submodules which are two cascaded variable geometry truss structures working in mutually orthogonal planes and a discrete twister. The manipulator is assumed to be powered with pneumatic on-off actuators. Because of the discrete nature of the binary actuators, a small but continuously actuated manipulator with six degrees of freedom is installed as the last module of the HRM in order to compensate the discretization errors. To solve the inverse kinematics problem of the HRM, three methods have been presented. These are the spline fitting, the extended spline fitting, and the workspace filling methods. The spline fitting method is based on forcing the spine (i.e. the center line) of the manipulator to approximate a spatial reference spline which is specified as a desired curve. In the extended spline fitting method, the result found in the first method is improved by using a genetic algorithm. In the work space filling method, the workspace of the manipulator is filled randomly with a sufficiently large finite number of discrete configurational samples. If it is desired to have concentration on a particular region of the work space, then that region is filled by using a genetic algorithm. After the filling stage, the sample closest to the desired configuration is determined by a suitable search algorithm. Finally, in order to simulate the motion of the HRM between two successive configurational steps, the equations of motions of the HRM are obtained in terms of the pressure forces generated by the binary pneumatic actuators. Then, the necessary simulations are carried out to demonstrate the performance of the HRM in some typical applications.

In this thesis study, a two-fingered gripper and a four-fingered multipurpose gripper are developed and manufactured. In addition to development of robotic hands, computer control hardware and software are also developed for computer control of both hands. The two-fingered gripper is designed for a specially defined pick and place operation. Its task is to pick a cylindrical work piece and place it in the appropriate position in a flexible manufacturing cell. Pneumatic actuator is used for power generation and mechanical links are used for power transmission. Fourfingered gripper is designed as a multipurpose gripper. The task is not predefined for this gripper, so, human hand and previous dexterous hands are taken as model during design. It consists of 3 fingers and a thumb. It has 1 degree of freedom for every finger and thumb. Pneumatic actuators are also used for this gripper. Rope and pulley system is used for the power transmission mechanism. Structures of both hands are manufactured from 5083 series aluminum. Gripping force can be controlled by the pressure regulator of the pneumatic system for both hands. Computer software is developed for the control of open and close motion of the fingers. Also, a motion control card is designed and manufactured for control of the pneumatic valves.

The main goal of this thesis is to simulate the response of a humanoid robot using a specified control algorithm which can achieve a sustainable biped locomotion with 4 basic locomotion phases. Basic parts for the body of the humanoid robot model are shaped according to the specified basic physical parameters and assumed kinematic model. The kinematic model, which does not change according to locomotion phases and consists of 27 segments including 14 virtual segments, provides a humanoid robot model with 26 degrees of freedom (DOF). Corresponding kinematic relations for the robot model are obtained by recursive formulations. Derivation of dynamic equations is carried out by the Newton-Euler formulation. A trajectory definition algorithm which defines positions, orientations, translational and angular velocities for the hip and its mass center, toe part of the foot and its toe point is created. A control strategy based on predictive optimum command acceleration calculations and computed torque control method is implemented. The simulation is executed in Simulink and the visualization of the simulation is established in a virtual environment by Virtual Reality Toolbox of MATLAB. The simulation results and the user defined reference input are displayed simultaneously in the virtual environment. In this study, a simulation environment for the biped locomotion of humanoid robots is created. By the help of this thesis, the user can test various control strategies by modifying the modular structure of the simulation and acquire necessary information for the preliminary design study of a humanoid robot construction.

In this thesis, numerical and experimental design of a multi-frequency underwater acoustic transducer with cylindrical piezoelectric ceramic tubes is studied. In the numerical design, the acoustic, mechanical and thermal performances of the transducer are investigated by means of finite element method (FEM) in ANSYS. The design of the transducer that meets the acoustic requirements is checked in terms of the mechanical and thermal performances. After the completion of the numerical design, the transducer is manufactured and some performance tests such as impedance test, hydrostatic pressure test and full-power operation test are applied to it. Finally, the results of the numerical and experimental design are compared. As a result, the design of an underwater acoustic transducer that operates at two frequency bands centered at about 30 and 60 kHz under a hydrostatic pressure of 30 bars is accomplished. This transducer also resist to a shock loading of 500g for 1 millisecond.