Zugl.: Bayreuth, Universiẗat, Diss., 2008.

Zugl.: Aachen, Techn. Hochsch., Diss., 2008. / Hergestellt on demand.

No description available.

No description available.

This research builds up on recent results in planar kinematic synthesis with contact direction and curvature constraints on the workpiece. The synthesis of spherical serial chains is considered to guide a rigid body, such that it does not violate normal direction and curvature constraints imposed by contact with objects in the environment. These constraints are transformed into conditions on the velocity and acceleration of points in the moving body to obtain synthesis equations which can be solved by algebraic elimination. Trajectory interpolation formulas yield the movement of the chain with the desired contact properties in each of the task positions. Example shows the application of the developed theory to the failure recovery of a robot manipulator.

Industrial robots and automation technology have advanced rapidly in the last several decades. New types of manipulators that uses parallel mechanisms are becoming more popular due to their high speed and high stiffness. This thesis focuses on a sub-class of parallel manipulators that uses cables to replace rigid links for further increase in speed. The design strategies in this study were expanded from research works by Khajepour. Behzadipour, and Edmon Chan. This thesis presents analysis and development of a new cable-based planar parallel manipulator that is based on a previous prototype built by Edmon Chan. The new manipulator design added a new rotational DOF to the end-effector, and the number of cables are doubled in order to increase the stiffness. New methods for kinematics and dynamics analysis are formulated to make the procedure more systematic. A new mathematical formulation for stiffness matrix of the end-effector is presented. The resultant stiffness matrix is equivalent to the stiffness matrix formulated by Behzadipour. Additional stiffness analysis is conducted on valid range of stiffness calculation and comparison of different cable configurations. A multi-objective optimization problem is formulated in order to search for the best set of design parameters for the manipulator, and it is solved with an exhaustive complete search method. A physical prototype of the manipulator is modelled and manufactured with the help of partners from Conestoga college. Experiments with the manipulator show that more powerful motors are needed to run the robot at full speed. Motor torque measurements show that the dynamics analysis of the manipulator is valid. Stiffness of the manipulator is measured by applying external force to the end-effector, and it is shown to be strong. The manipulator is able to demonstrate a sort and pick-and-place operation at 60 cycles per minute while running at 70% of the maximum speed, with an acceleration of 2.8 g and velocity of 4 m/s.

Zugl.: Braunschweig, Techn. Univ., Diss., 2009

This thesis focuses on the methods and results of the workspace formulation of wire-actuated parallel manipulators. Four methods of workspace generation are studied. The null space method, based on the calculation of wire tensions, is used to formulate the workspaces of example manipulators. The results of this method are used to verify the results of the following methods. This thesis presents that the convex hull workspace formulation method, a geometric analysis of the manipulator’s Jacobian matrix, can be extended to manipulators that have an external wrench and/or gravity applied to the mobile platform. The convex hull method is applied to the example manipulators investigated with the null space method. The workspace envelope characterization, an analytical approach of defining the borders of the workspace using the formulation of the kernel of the manipulator’s Jacobian matrix, is applied to the example planar manipulators investigated with the previous methods. A new process, presented in this thesis, of identifying the contribution of each set of four wires/forces of a planar manipulator allows the workspace envelope characterization to be applied to redundant planar manipulators and planar manipulators that have an external wrench and/or gravity applied to the mobile platform. The discrete and analytical antipodal methods, based on theorems from multi-fingered grasping manipulators, are presented and applied to the example planar manipulators investigated with the previous methods. This research generalizes the use of these theorems, which determine wrench-closure poses of planar four-wire manipulators that share wire-connection points on the base or mobile platform, to the discrete and analytical workspace formulation of planar three-degree-of-freedom wire-actuated manipulators with no restrictions on the number of wires or the configuration of the manipulator. Comparing all methods investigated in this thesis, the null space method results in the workspace that takes into account the maximum and minimum wire tensions and is recommended for use in the design of both spatial and planar wire-actuated parallel manipulators. All the other methods presented in this thesis, have similar results when compared to the null space method but formulate the maximum workspace which assumes the wires can operate with very high to infinite wire tension. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-10-14 09:02:25.562

This thesis presents the design of a personal computer (PC) based needle insertion robotic manipulator for biopsy. The robot was designed and built using materials available in the research laboratory. The robot is intended primarily for use inside the confined area of a cylindrical magnetic resonance (MR) scanner. Selection of the robot geometry and novel locations for drive actuators allowed placement of actuators outside the MRI bore. The robot is modeled using Denavit-Hartenberg transformations. Custom developed software control is developed to test the functional aspects of the robot. The robot performs to the tolerance required for the stated clinical application. This thesis addresses only proof of concept chosen for the manipulator design and is not ready for any clinical trials. The work also addresses MRI compatible and safety issues and recommends appropriate materials for future development. Traditionally, neurosurgical navigation has relied on preoperative images and the assumption that anatomical structures of interest remain in the same position with respect to each other and the fiducial markers used for registration. However, during surgery, tissue deformation and shift disrupt the spatial relation between the patient and the preoperative image volumes. This results in localization errors. Developing a manipulator that works inside an imaging machine guided by real time images is expected to minimize the problem of “tissue shift” during the surgery.

This thesis presents the design of a personal computer (PC) based needle insertion robotic manipulator for biopsy. The robot was designed and built using materials available in the research laboratory. The robot is intended primarily for use inside the confined area of a cylindrical magnetic resonance (MR) scanner. Selection of the robot geometry and novel locations for drive actuators allowed placement of actuators outside the MRI bore. The robot is modeled using Denavit-Hartenberg transformations. Custom developed software control is developed to test the functional aspects of the robot. The robot performs to the tolerance required for the stated clinical application. This thesis addresses only proof of concept chosen for the manipulator design and is not ready for any clinical trials. The work also addresses MRI compatible and safety issues and recommends appropriate materials for future development. Traditionally, neurosurgical navigation has relied on preoperative images and the assumption that anatomical structures of interest remain in the same position with respect to each other and the fiducial markers used for registration. However, during surgery, tissue deformation and shift disrupt the spatial relation between the patient and the preoperative image volumes. This results in localization errors. Developing a manipulator that works inside an imaging machine guided by real time images is expected to minimize the problem of “tissue shift” during the surgery.