Kinematics and workspace analysis of a 3ppps parallel robot with u-shaped base

This paper presents the kinematic analysis of the 3-PPPS parallel robot with an equilateral mobile platform and a U-shape base. The proposed design and appropriate selection of parameters allow to formulate simpler direct and inverse kinematics for the manipulator under study. The parallel singularities associated with the manipulator depend only on the orientation of the end-effector, and thus depend only on the orientation of the end effector. The quaternion parameters are used to represent the aspects, i.e. the singularity free regions of the workspace. A cylindrical algebraic decomposition is used to characterize the workspace and joint space with a low number of cells. The dis-criminant variety is obtained to describe the boundaries of each cell. With these simplifications, the 3-PPPS parallel robot with proposed design can be claimed as the simplest 6 DOF robot, which further makes it useful for the industrial applications

Computer simulation and design of a three degree-of-freedom shoulder module

An in-depth kinematic analysis of a three degree of freedom fully-parallel robotic shoulder module is presented. The major goal of the analysis is to determine appropriate link dimensions which will provide a maximized workspace along with desirable input to output velocity and torque amplification. First order kinematic influence coefficients which describe the output velocity properties in terms of actuator motions provide a means to determine suitable geometric dimensions for the device. Through the use of computer simulation, optimal or near optimal link dimensions based on predetermined design criteria are provided for two different structural designs of the mechanism. The first uses three rotational inputs to control the output motion. The second design involves the use of four inputs, actuating any three inputs for a given position of the output link. Alternative actuator placements are examined to determine the most effective approach to control the output motion

Kinematics and Workspace Analysis of a Three-Axis Parallel Manipulator: the Orthoglide

The paper addresses kinematic and geometrical aspects of the Orthoglide, a three-DOF parallel mechanism. This machine consists of three fixed linear joints, which are mounted orthogonally, three identical legs and a mobile platform, which moves in the Cartesian x-y-z space with fixed orientation. New solutions to solve inverse/direct kinematics are proposed and we perform a detailed workspace and singularity analysis, taking into account specific joint limit constraints

Kinematic and dynamic analysis of spatial six degree of freedom parallel structure manipulator

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2003Includes bibliographical references (leaves: 63-69)Text in English; Abstract: Turkish and Englishviii, 86 leavesThis thesis covers a study on kinematic and dynamic analysis of a new type of spatial six degree of freedom parallel manipulator. The background for structural synthesis of parallel manipulators is also given. The structure of the said manipulator is especially designed to cover a larger workspace then well-known Stewart Platform and its derivates. The main point of interest for this manipulator is its hybrid actuating system, consisting of three revolute and three linear actuators.Kinematic analysis comprises forward and inverse displacement analysis. Screw Theory and geometric constraint considerations were the main tools used. While it was possible to derive a closed-form solution for the inverse displacement analysis, a numerical approach was used to solve the problem of forward displacement analysis. Based on the results of the kinematic analysis, a rough workspace study of the manipulator is also accomplished. On the dynamics part, attention has been given on inverse dynamics problem using Lagrange-Euler approach.Both high and lower level software were heavily utilized. Also computer software called .CASSoM. and .iMIDAS. are developed to be used for structural synthesis and inverse displacement analysis. The major contribution of the study to the scientific community is the proposal of a new type of parallel manipulator, which has to be studied extensively regarding its other interesting properties

Design of a Modified Stewart Platform Manipulator for Misalignment Correction

This thesis work is about the design of a modified Stewart platform manipulator for misalignment correction. The common version of the Stewart platform uses six actuators. The traditional Stewart platform of this kind has a moving top plate and a fixed base plate. However, in this research, the modified design of the traditional Stewart platform is studied. It is designed to be an easy connect-disconnect platform that can wrap around different structures with different cross sections and symmetrically designed. It is able to adjust position easily by using four identical but independent linear actuators populated evenly in two parts fastened to the top and bottom base by ball joints with each part been symmetrical to the other. To design two symmetrical parts and an adjustable clamp are a major objective of the thesis. One symmetrical part flipped upside down produces the other. The adjustable clamp was printed in 3D and can be used to align regular structural shapes especially circle of various diameter. To correct the misalignment, a failure study was carried out to determine the two equal but opposite loads required to correct misalignment in two plastic beams. Five loads were applied which showed that the smaller the load, the better the misalignment. This study showed that it is better to fix the base at a location where it does not move. To investigate that the modified Stewart platform can resist structure stiffness, the actuator assembly was analyzed using ANSYS software. The results showed that the deformation and maximum stress is less that the structure stiffness, which proves why the assembly can resist structural stiffness. The results support that the modified Stewart platform can be used for misalignment correction