No description available.

No description available.

No description available.

This thesis explores the possibility of using mechanical control in the design of a complex end effector. A design methodology is developed and demonstrated. The main goal of this methodology is to maximize reversible steps to direct the design. By attempting to obtain as much mechanical control as possible, several mechanisms are developed which could be used in applications where control of multiple operations by one motor is desired. Along with the demonstration of the design methodology with an end effector design, the application of this methodology to cigarette packaging machines is discussed. / Master of Science

In this thesis, forward and inverse kinematic equations are developed for a parallel, closed-loop manipulator known as the Variable Geometry Truss or VGT for short. Widely recognized as adaptive or collapsing structures for space and military applications, VGTs have not received due consideration as robotic manipulators. VGTs undoubtedly represent an important sector of future manipulator applications. VGTs are typically constructed using repeating identical cells or modules and they have exceptional stiffness to weight ratios. The data obtained from solving the forward kinematic equations is used for animation of the VGT. For animation, three dimensional graphics software, graPHIGS is used. Additionally, the kinematic analysis equations are used to map out workspace of the VGT. An experiment is also carried out to verify the computational results. / Master of Science

This work bridges the gap between theory and practice. The development of general inverse kinematic solution techniques is new, hence few detailed applications of these methods exist. Before methods such as these were available, most commercial manipulators were designed to be geometrically simple, yielding 4th or lower degree governing equations. With the further development and application of these techniques, industry will be capable of implementing more complex manipulators for highly specialized tasks. A general inverse kinematic analysis technique is applied to an industrial manipulator designed for the inspection of nuclear reactor vessels. The analysis is performed by solving the 16th degree univariate displacement polynomial of the general six-degree-of-freedom arm using an equivalent seven-degree-of-freedom closed-loop spatial chain. All possible combinations of joint angles for a given hand position and orientation are obtained. A region in which the manipulator has the maximum number of solutions is used as a numerical example. The inverse kinematic analysis was programmed in C, which is included in Appendix D. / Master of Science

The focus of this work is the real-time prediction and compensation of static deflections in robotic manipulator arms. A general manipulator deflection model is developed based on static beam theory and robot kinematics. An optimization technique is proposed to determine the stiffness of the manipulator components using end-effector deflection measurements. Strategies for incorporating this modeling approach into a manipulator controller are also presented along with the results of a successful application of this research. This work is an extension of previous manipulator deflection research. Multiple pairs of torsional stiffness elements and beam elements are used to model complex link and joint geometries whereas previous models only used a single beam per manipulator link. In addition, the modeling algorithms and stiffness characterization methods are general and may be applied directly to any serial manipulator. Also, the optimization techniques used to characterize a manipulator's stiffness provide a more accurate and flexible approach than previous analytical methods. The deflection model was successfully tested using a nuclear steam generator service manipulator. Since this manipulator is considerably more flexible than common industrial robots, it serves as a near worst-case test for deflection modeling. The end effector was found to deflect as much as 1.5 inches due to the weight of the links and joints. The deflection model was able to compensate for 94% of the end-effector deflection, allowing the manipulator to perform tasks requiring a positioning accuracy of 0.09 inches. The algorithms for flexible forward and inverse kinematics as well as trajectory generation were incorporated directly into the manipulator controller code. These modules were capable of running in real-time with little computational expense. / Master of Science

No description available.

Un manipulateur parallèle à mobilité réduite a moins de six degrés de liberté et présente généralement différents types de mouvement connus sous le nom de modes d'opération. Ainsi, ce type de manipulateur peut être classifié comme reconfigurable selon sa capacité de transition entre les différents modes d'opération. Cette thèse de doctorat s'articule principalement autour de l'analyse cinématique de manipulateurs parallèles à mobilité réduite, de manipulateurs parallèles en série obtenus à partir de leur empilement en série et de mécanismes conformes conçus à partir de leurs configurations singulières à contraintes. La transformation cinématique de Study est utilisée pour dériver les équations algébriques de contraintes. Ensuite, elles sont interprétées à l'aide d'outils de géométrie algébrique pour effectuer des analyses de mobilité, de cinématique et de singularité. Les techniques de ‘‘screw theory’’ et ‘‘line geometry’’ sont utilisées à côté de l'approche algébrique au besoin. / A lower mobility parallel manipulator has less than six degrees of freedom and usually exhibits different motion types known as operation modes. Thus, it can be classified as reconfigurable on account of its ability to transition between different operation modes. This doctoral thesis mainly revolves around the kinematic analysis of some lower-mobility parallel manipulators, series-parallel manipulators obtained from their serial stacking and compliant mechanisms designed using their constraint singular configurations. Study's kinematic mapping is used to derive the algebraic constraint equations. They are further interpreted using algebraic geometry tools to perform mobility, kinematic and singularity analysis. Screw theory and line geometry techniques are used adjacent to algebraic approach wherever necessary.

The growing need in industrial applications of high-performance robots has led to designs of lightweight robot arms. However the light-weight robot arm introduces accuracy and vibration problems. The classical robot design and control method based on the rigid body assumption is no longer satisfactory for the light-weight manipulators. The effects of flexibility of light-weight manipulators have been an active research area in recent years. A new approach to correct the quasi-static position and orientation error of the end-effector of a manipulator with flexible links is studied in this project. In this approach, strain gages are used to monitor the elastic reactions of the flexible links due to the weight of the manipulator and the payload in real time, the errors are then compensated on-line by a control algorithm. Although this approach is designed to work for general loading conditions, only the bending deflection in a plane is investigated in detail. It is found that a minimum of two strain gages per link are needed to monitor the deflection of a robot arm subjected to bending. A mathematical model relating the deflections and strains is developed using Castigliano's theorem of least work. The parameters of the governing equations are obtained using the identification method. With the identification method, the geometric details of the robot arms and the carrying load need not be known. The deflections monitored by strain gages are fed back to the kinematic model of the manipulator to find the position and orientation of the end-effector of the manipulator. A control algorithm is developed to compensate the deflections. The inverse kinematics that includes deflections as variables is solved in closed form. If the deflections at target position are known, this inverse kinematics will generate the exact joint command for the flexible manipulator. However the deflections of the robot arms at the target position are unknown ahead of time, the current deflections at each sampling time are used to predict the deflections at target position and the joint command is modified until the required accuracy is obtained. An experiment is set up to verify the mathematical model relating the strains to the deflections. The results of the experiment show good agreement with the model. The compensation control algorithm is first simulated in a computer program. The simulation also shows good convergence. An experimental manipulator with two flexible links is built to prove this approach. The experimental results show that this compensation control improves the position accuracy of the flexible manipulator significantly. The following are the brief advantages of this approach: the deflections can be monitored without measuring the payload directly and without the detailed knowledge of link geometry~ the manipulator calibrates itself with minimum human intervention; the compensation control algorithm can be easily integrated with the existing uncompensated rigid-body algorithm~ it is inexpensive and practical for implementation to manipulators installed in workplaces.