Analysis and synthesis of parallel manipulators

Thesis (Doctoral)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2008Includes bibliographical references (leaves: 131-138)Text in English; Abstract: Turkish and Englishxiv, 142 leavesIn this study, novel parallel manipulators are introduced for industrial and medical applications. New methods are developed for the structural synthesis of Euclidean platform robot-manipulators with variable general constraints (EPRM). New mechanical structures such as serial, parallel and serial-parallel EPRM are designed along with proposed method.A new dimensional synthesis method of two DoF planar and spherical seven link mechanisms is presented. Interpolation and least square approximations are used to design the mechanism. In the solution of dimensional synthesis problems, nonlinear equations are converted to system of linear equations. The motion generation problem of a 3 DoF platform robot manipulator is solved for three, four and five precision poses. It is shown that the synthesis problem can be solved analytically for three prescribed poses. However, the solution is achieved by using a numerical method for four and five poses. The result, which is obtained from three prescribed poses, is used as an initial guess for four and five poses. Kinematic analysis of the manipulators is investigated. After the derivation of vector-loop equations, inverse and direct position analyses of the manipulators are presented. Constant orientation workspace of a three DoF spatial parallel manipulator is presented. The mechanical elements which are necessary for the construction of manipulators are introduced. The information about the motors which is needed for actuation of manipulators is given. Three DoF parallel manipulator is constructed for a industrial packaging system. Assembly of manufactured parts and mechanical elements are shown

Uzaysal mekanizmalarda atalet parametrelerinin tasarımı

In this thesis, the inertial parameters of a spatial mechanism are used in order to optimize various aspects of the dynamic behaviour of the mechanism (such as minimizing actuator torque/ force fluctuations, shaking force/moment balancing, etc.) while the effects of loads are considered as well. Here, inertial parameters refer to the mass, 6 elements of the inertia tensor and coordinates of the center of mass of the links. The concept of Force Fluctuation Number (FFN) is utilized to optimize the dynamic behaviour of the mechanism. By using the FFN concept, one obtains a number of linear equations to be satisfied by the optimal inertial parameters. In general, the number of such equations is less than the number of the inertial parameters. Therefore, some of the inertial parameters may be selected freely in order to satisfy other design constraints. Using MATHEMATICA, a program has been developed to obtain the linear equations to be satisfied by the optimal inertial parameters. The developed program includes a kinematic and force analysis module, which can be used independently for a complete kinematic and dynamic analysis of any one degree of freedom, single loop, spatial mechanism. The different closures of the mechanism may be identified by using the developed package and these analyses can be performed on any selected closure of the mechanism.M.S. - Master of Scienc

Least square approximate motion generation synthesis of spherical linkages by using Chebyshev and equal spacing

WOS: 000314011700008In this paper, approximate motion synthesis of spherical linkages is presented. Rigid body guidance of a spherical four-bar mechanism is performed by a spherical RR open chain. In the first step, position of a point on rigid body and orientation of a rigid body on a unit sphere are described. Synthesizing function of spherical dyad is derived by means of using unit vectors that describe location of two revolute joints and tip point. Being based on the theory of function approximation and besides the linearization of nonlinear synthesis equations by using superposition method, the design procedure for real solutions of fourth order polynomial equation is developed. In the second step, approximate motion generation synthesis of spherical dyad is presented by using least-square approximation. Chebyshev spacing and equal spacing are used in the determination of poses. In the final step, two numerical examples are given to show how error graph is varied in terms of selected poses. The spherical motion generation synthesis of spherical four-bar mechanism is obtained by the combination of the two real solutions of the synthesis of two spherical dyads. (C) 2012 Elsevier Ltd. All rights reserved

Structural synthesis of Euclidean platform robot manipulators with variable general constraints

In this paper, new method for structural synthesis of Euclidean platform robot manipulators with variable general constraints (EPRM) is presented. Three dimensional motion of the base moving platform is generated by the motion of dyads on the Euclidean planes. Each dyad is connected to the moving base platform by universal, spherical or spherical in torus (St) kinematic pairs. This allows solving the structural synthesis of Euclidean robot manipulators with various DoF and different platform motions. New structural formulations with variable general constraints for the platform motion and the mobility of robot manipulators are presented. The new structural classification of simple structural groups with variable general constraints including platforms, hinges, legs and branch loops from different subspaces and space is also introduced. Moreover, new method for structural synthesis of serial, parallel and serial-parallel EPRM is illustrated along with examples. © 2007 Elsevier Ltd. All rights reserved

Development of Trajectory Design of a Planar PRR Redundant Serial Manipulator

Robot usage in the industry increase every year by the developments in technology. Industrial robots not only timesaver but also ensures the quality of the products in machining operations. Robots specialized for machine tool operations have limited utilization compared to those which for assembly, welding, or pick & place operations. In this paper we focused on the development and verification of a planar manipulator path trajectory which will going to do surface finishing operation on a work piece. To do this first we define a desired path and the unknown coefficients of joint variables have been calculated by performing direct and inverse kinematic analysis and applying the conditions of position, velocity, and acceleration of the given trajectory. Obtained trajectory of the end effector has been tested on both simulation and real task space. Results of theoretically calculated trajectory have been verified by computational simulation and end-effector trajectory of the prototype has been verified via motion tracking system with cameras

Development of Augmented Reality Application for Teaching Mechanism and Robotics in ROS

In this research, we present an approach to development of augmented reality application for teaching mechanism and robotics in ROS (Robot Operating System). Our approach uses Unity (Vuforia), ROS and SolidWorks that allows a user to specify high-level requests to the 6 degree of freedom robot manipulator, to build, approve or modify the computed robot motions. The proposed approach exploits requiring low-level motion specifications provided by the user. Furthermore, the robot can be used in education purposes. In the end, we present a discussion of its applicability in collaborative environments

Design of Hexapod Walking Robot with Double Scara Legs

Many walking prototypes have one or more degree of freedom leg mechanisms to obtain walking trajectory. Kinematic synthesis of one degree of freedom mechanisms is required to calculate correct links lengths according to desired trajectory. In this study, we designed, controlled, and tested a six-legged walking robot with double scara legs. Two actuators of double scara robot allows us to arrange any trajectory within workspace of our leg design. Three legs of them are working simultaneously to obtain smooth walking on terrain. Each servo motor attached to leg is working independently. Therefore, we can arrange several movements besides walking. Many parts of our walking robot which are necessary for assembly were designed in SolidWorks. These parts were printed by using a Ultimaker 3D printer with PLA material. Servo actuators of robot was controlled by using PWM pins of Arduino Mega microcontroller. We tested our robot using three different leg trajectories such as square, triangle and smooth trajectories. According to our test, we observed that smooth trajectory is the most energy efficient

Electromagnet design for untethered actuation system mounted on robotic manipulator

Electromagnetic actuation systems have remarkably proved themselves in the field of contactless power transmission systems. Nevertheless, the stationary position of the operated electromagnets or their rotation around a fixed axis resulted in a restrictive and limited versatile workspace. In this paper, a new design of a steel cored solenoidal coil is proposed for a novel microrobot electromagnetic actuator. The new system combines a 6 DOF industrial robotic manipulator with co-axially movable electromagnets. Considering the maximum weight and workspace limitations of the robotic manipulator, seven essential dimensions of the electromagnet were investigated with the aid of a simulation software. A set of parametric studies were carried out in order to optimize the homogeneity of the induced magnetic field at the highest achievable intensity based on Ad hoc method. The results showed that an electromagnet with a square prism core and a large front, induces a more homogeneous and intense magnetic field. Moreover, by shortening the length of the coil and increasing the length of the core, the intensity of the magnetic field significantly increases without much affecting its homogeneity. The electromagnet was fabricated according to the final result of the numerical studies and evaluated by performing experimental measurements on the induced magnetic field. Furthermore, with several programed motions, the performance of the proposed untethered electromagnetic actuation system was demonstrated experimentally. (C) 2018 Elsevier B.V. All rights reserved