Self-motion control of kinematically redundant robot manipulators

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2012Includes bibliographical references (leaves: 88-92)Text in English; Abstract: Turkish and Englishxvi,92 leavesRedundancy in general provides space for optimization in robotics. Redundancy can be defined as sensor/actuator redundancy or kinematic redundancy. The redundancy considered in this thesis is the kinematic redundancy where the total degrees-of-freedom of the robot is more than the total degrees-of-freedom required for the task to be executed. This provides infinite number of solutions to perform the same task, thus, various subtasks can be carried out during the main-task execution. This work utilizes the property of self-motion for kinematically redundant robot manipulators by designing the general subtask controller that controls the joint motion in the null-space of the Jacobian matrix. The general subtask controller is implemented for various subtasks in this thesis. Minimizing the total joint motion, singularity avoidance, posture optimization for static impact force objectives, which include maximizing/minimizing the static impact force magnitude, and static and moving obstacle (point to point) collision avoidance are the subtasks considered in this thesis. New control architecture is developed to accomplish both the main-task and the previously mentioned subtasks. In this architecture, objective function for each subtask is formed. Then, the gradient of the objective function is used in the subtask controller to execute subtask objective while tracking a given end-effector trajectory. The tracking of the end-effector is called main-task. The SCHUNK LWA4-Arm robot arm with seven degrees-of-freedom is developed first in SolidWorks® as a computer-aided-design (CAD) model. Then, the CAD model is converted to MATLAB® Simulink model using SimMechanics CAD translator to be used in the simulation tests of the controller. Kinematics and dynamics equations of the robot are derived to be used in the controllers. Simulation test results are presented for the kinematically redundant robot manipulator operating in 3D space carrying out the main-task and the selected subtasks for this study. The simulation test results indicate that the developed controller’s performance is successful for all the main-task and subtask objectives

A comparative study on application of decomposition method in function generation synthesis of over-constrained mechanisms

Double-spherical six-bar linkage is one of the Bennett over-constrained 6R linkages. Kinematic synthesis of such linkages can be tedious and impossible to solve for analytically. In order to cope with higher number of unknowns in these types of linkages, decomposition method is a valuable tool. This paper focuses on the function generation synthesis of double-spherical six-bar linkage. Two procedures for applying decomposition method are explained. Two numerical studies are conducted for both procedures to evaluate the performance of each procedure

Self-motion control of kinematically redundant robot manipulators

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2012Includes bibliographical references (leaves: 88-92)Text in English; Abstract: Turkish and Englishxvi,92 leavesRedundancy in general provides space for optimization in robotics. Redundancy can be defined as sensor/actuator redundancy or kinematic redundancy. The redundancy considered in this thesis is the kinematic redundancy where the total degrees-of-freedom of the robot is more than the total degrees-of-freedom required for the task to be executed. This provides infinite number of solutions to perform the same task, thus, various subtasks can be carried out during the main-task execution. This work utilizes the property of self-motion for kinematically redundant robot manipulators by designing the general subtask controller that controls the joint motion in the null-space of the Jacobian matrix. The general subtask controller is implemented for various subtasks in this thesis. Minimizing the total joint motion, singularity avoidance, posture optimization for static impact force objectives, which include maximizing/minimizing the static impact force magnitude, and static and moving obstacle (point to point) collision avoidance are the subtasks considered in this thesis. New control architecture is developed to accomplish both the main-task and the previously mentioned subtasks. In this architecture, objective function for each subtask is formed. Then, the gradient of the objective function is used in the subtask controller to execute subtask objective while tracking a given end-effector trajectory. The tracking of the end-effector is called main-task. The SCHUNK LWA4-Arm robot arm with seven degrees-of-freedom is developed first in SolidWorks® as a computer-aided-design (CAD) model. Then, the CAD model is converted to MATLAB® Simulink model using SimMechanics CAD translator to be used in the simulation tests of the controller. Kinematics and dynamics equations of the robot are derived to be used in the controllers. Simulation test results are presented for the kinematically redundant robot manipulator operating in 3D space carrying out the main-task and the selected subtasks for this study. The simulation test results indicate that the developed controller’s performance is successful for all the main-task and subtask objectives

Physical human-robot interaction: Increasing safety by robot arm’s posture optimization

To have robot manipulators working alongside with humans is a necessity in service robots. Obviously, in these robotics applications, human safety has precedence over precision and repeatability, which are the most important qualification of the conventional industrial manipulators. The safety measures can be taken either in the hardware or in the software or in both. This work by using a redundant manipulator aims at providing a safety measure through controlling the self-motion of the manipulator. The self-motion of the manipulator is controlled to change the posture of the manipulator to minimize or maximize the forces it can exert along a given direction. In this way, by knowing the location of the human or a delicate piece that it should not harm, manipulator’s posture is optimized to exert the minimum amount of forces during an unexpected collision. The control algorithm for this objective is described in this paper and it is evaluated through simulation tests on a redundant lightweight robot manipulator.The Scientific and Technological Research Council of Turkey via grant number 115E72

Experimental verification of quasi-static equilibrium analysis of a haptic device

HIPHAD v1.0 is a kinesthetic haptic device which was designed and manufactured in IzTech Robotics Laboratory. In this work, the quasi-static equilibrium analysis is carried out by including the gravitational effects. The calculations are verified through an experimental procedure and the results are presented to characterize the device performance.The Scientific and Technological Research Council of Turke

Unilateral teleoperation design for a robotic endoscopic pituitary surgery system

5th International Workshop on Medical and Service Robots, MeSRob 2016; Graz; Austria; 4 July 2016 through 6 July 2016The aim of this study is to develop a teleoperation system which will be used to support the endoscopic pituitary surgery procedures. The proposed system aims to enable the surgeon to operate with three different operation tools (one of them is the endoscope) simultaneously. By this way, it is expected that the productivity of the surgical operation will be improved and the duration of the operation will be shortened. In the proposed system, a main control unit that can be attached to any of the surgical tools that are used in the operation (other than the endoscope) will be developed to capture the motion of the surgeon’s hand motion as demanded by the surgeon, to process the captured motion and to send it to the robot that handles the endoscope. In this way, the endoscope will be directed simultaneously by the surgeon throughout the operation while he/she is using the other surgical tools with his/her two hands. In this paper, the study to determine the type and processing of information that is sent from the surgeon’s side to the endoscope robot is presented.Scientific and Technological Research Council of Turkey (115E725 / 115E726