This thesis presents two unique micro-motion parallel kinematic manipulators (PKM): a three degrees of freedom (3-DOF) micro-motion manipulator and a 3-DOF micro-motion manipulator with actuation redundancy. The 3-DOF micro-motion manipulator has three linear-motion driving units, and the 3-DOF micro-motion manipulator with redundancy has four of these units. For both designs, the linear motion driving units are identical, and both machines have a passive link in the center of the structure. The purpose of this passive link is to restrain the movement of the manipulator and to improve the stiffness of the structure. As a result, both structures support 3-DOF, including one translation on the Z-axis and two rotations around the X and Y axes. The manipulator with redundancy is designed to prevent singularity and to improve stiffness. In this thesis, the inverse kinematic, Jacobian matrix and stiffness analyses have been conducted, followed by the design optimization for structures. Finally, the FEA (Finite Element Analysis) and dynamic analysis have also been performed. There are many practical applications for micro-motion parallel manipulators. The typical applications include micro-machine assembly, biological cell operation, and microsurgery . / UOIT

Parallel manipulators have been the subject of study of much robotic research during the past three decades. A parallel manipulator typically consists of a moving platform that is connected to a fixed base by at least two kinematic chains in parallel. Parallel manipulators can provide several attractive advantages over their serial counterpart in terms of high stiffness, high accuracy, and low inertia, which enable them to become viable alternatives for wide applications. But parallel manipulators also have some disadvantages, such as complex forward kinematics, small workspace, complicated structures, and a high cost. To overcome the above shortcomings, progress on the development of parallel manipulators with less than 6-DOF has been accelerated. However, most of presented parallel manipulators have coupled motion between the position and orientation of the end-effector. Therefore, the kinematic model is complex and the manipulator is difficult to control. Only recently, research on parallel manipulators with less than six degrees of freedom has been leaning toward the decoupling of the position and orientation of the end-effector, and this has really interested scientists in the area of parallel robotics. Kinematic decoupling for a parallel manipulator is that one motion of the up-platform only corresponds to input of one leg or one group of legs. And the input cannot produce other motions. Nevertheless, to date, the number of real applications of decoupled motion actuated parallel manipulators is still quite limited. This is partially because effective development strategies of such types of closed-loop structures are not so obvious. In addition, it is very difficult to design mechanisms with complete decoupling, but it is possible for fewer DOF parallel manipulators. To realize kinematic decoupling, the parallel manipulators are needed to possess special structures; therefore, investigating a parallel manipulator with decoupling motion remains a challenging task. This thesis deals with lower mobility parallel manipulator with decoupled motions. A novel parallel manipulator is proposed in this thesis. The manipulator consists of a moving platform that is connecting to a fixed base by three legs. Each leg is made of one C (cylinder), one R (revolute) and one U (universal) joints. The mobility of the manipulator and structure of the inactive joint are analyzed. Kinematics of the manipulator including inverse and forward kinematics, velocity equation, kinematic singularities, and stiffness are studied. The workspace of the parallel manipulator is examined. A design optimization is conducted with the prescribed workspace. It has been found that due to the special arrangement of the legs and joints, this parallel manipulator performs three translational degrees of freedom with decoupled motions, and is fully isotropic. This advantage has great potential for machine tools and Coordinate Measuring Machine (CMM). / UOIT

10th IFAC Symposium on Robot Control International Federation of Automatic Control September 5-7, 2012. Dubrovnik, Croatia

abstract: As robots are increasingly migrating out of factories and research laboratories and into our everyday lives, they should move and act in environments designed for humans. For this reason, the need of anthropomorphic movements is of utmost importance. The objective of this thesis is to solve the inverse kinematics problem of redundant robot arms that results to anthropomorphic configurations. The swivel angle of the elbow was used as a human arm motion parameter for the robot arm to mimic. The swivel angle is defined as the rotation angle of the plane defined by the upper and lower arm around a virtual axis that connects the shoulder and wrist joints. Using kinematic data recorded from human subjects during every-day life tasks, the linear sensorimotor transformation model was validated and used to estimate the swivel angle, given the desired end-effector position. Defining the desired swivel angle simplifies the kinematic redundancy of the robot arm. The proposed method was tested with an anthropomorphic redundant robot arm and the computed motion profiles were compared to the ones of the human subjects. This thesis shows that the method computes anthropomorphic configurations for the robot arm, even if the robot arm has different link lengths than the human arm and starts its motion at random configurations. / Dissertation/Thesis / M.S.Tech Mechanical Engineering 2013

Goal of the thesis is to show the possibilities of using ordinary hobbyist RC servos and means of their control by a computer. For demonstration of the capabilities of servos, we have created Stewart platform which is using hobbyist servos to position the platform. In the thesis there is explained principle of the inner working of a servo, their properties, abilities and also means of their control by a computer. In practical chapters of the thesis there is documented process of designing and implementing of functional Stewart platform along with specific properties of this platform which influence its design. This platform is also reviewed and based on the results we will show technical properties of the platform, advantages and disadvantages of using ordinary hobbyist servos to control the platform. Design of the platform and its documentation is created with respect to intent to make the ddesign, source codes, documentation available to public on wepages focused on aggregating of instructables and tutorials to make usage of outputs possible in practice.

No description available.

In this study a universal command generator has been designed for robotics and CNC machinery. Encoding techniques has been utilized in order to represent the commands and their efficiencies have been discussed. The developed algorithm generates the trajectory of the end-effector with linear and circular interpolation in an offline fashion, the corresponding joint states and their error envelopes are computed with the utilization of a numerical inverse kinematic solver with a predefined precision. Finally, the command encoder employs the resulting data and produces the representation of positions in joint space with using proposed encoding techniques depending on the error tolerance for each joint. The encoding methods considered in this thesis are: Lossless data compression via higher order finite difference, Huffman Coding and Arithmetic Coding techniques, Polynomial Fitting methods with Chebyshev, Legendre and Bernstein Polynomials and finally Fourier and Wavelet Transformations. The algorithm is simulated for Puma 560 and Stanford Manipulators for a trajectory in order to evaluate the performances of the above mentioned techniques (i.e. approximation error, memory requirement, number of commands generated). According to the case studies, Chebyshev Polynomials has been determined to be the most suitable technique for command generation. Proposed methods have been implemented in MATLAB environment due to its versatile toolboxes. With this research the way to develop an encoding/decoding standard for an advanced command generator scheme for computer numerically controlled (CNC) machines in the near future has been paved.

No description available.

Der vorliegende Beitrag behandelt die kinematische und statische Analyse eines Biglide-Getriebes mit fünf Gliedern und zwei Schubantrieben zur Führung eines Punktes in der x-y-Ebene. Als mathematische Hilfsmittel werden die beiden Programme PTC Mathcad Prime 3.1 und GeoGebra 5.0 eingesetzt, die sich einander in hervorragender Weise ergänzen. Dabei ist Mathcad hier vorwiegend für Matrizenrechnungen und GeoGebra besonders anschaulich für geometrische Grundaufgaben mit Animationen zuständig. Die Effizienz der vorgestellten Algorithmen und Hilfsmittel wird anhand zweier Anwendungsbeispiele aufgezeigt.

The Compact Rescue Crawler is a pneumatic legged robot. Two legs of a hexapod were designed and built. The legs are controlled directly from operator inputs. The operator gives foot position inputs through two PHANToM haptic controllers. A PD controller with a supplementary force gain-scheduler control stroke lengths of each cylinder. The force-based position control technique allows the robot feet to track operator inputs to within 10% position error. A guided gait algorithm was developed to allow the operator to control all 6 legs simply by haptically guiding the front two. The operator records successful and collision-free trajectories and the gait coordinator plays the trajectories through the rear legs as they approach the detected obstacles. This hybrid gait algorithm allows the robot to proceed through a hazardous environment, guided by an operator, but without taxing the input capabilities of the human operator.