Constraint and Singularity Analysis of the Exechon Tripod

2012 ◽  
Author(s):  
Dimiter Zlatanov ◽  
Matteo Zoppi ◽  
Rezia Molfino
Keyword(s):  
Machine Tool ◽  
System Approach ◽  
Parallel Mechanism ◽  
Singularity Analysis ◽  
Geometric Interpretation ◽  
End Effector ◽  
Singular Configurations ◽  
Parallel Kinematic ◽  
Three Degree Of Freedom ◽  
Fixture System

The paper discusses mobility and singularities of the Exechon three-degree-of-freedom (dof) parallel mechanism (PM) on which a family of parallel kinematic machines is based. Exechon designs are used by a number of machine-tool makers. A new version of the manipulator has been developed as a component of a mobile self-reconfigurable fixture system within an inter-European project. The PM has two UPR (4-dof) legs, constrained to move in a common rotating plane, and an SPR (5-dof) leg. The paper focuses on the constraint and singularity analysis of the mechanism. The screw systems of end-effector freedoms and constraints are identified. The singular configurations are classified in detail and their geometric interpretation is discussed. The velocity kinematics and the Jacobian operator are formulated via a screw-system approach. A fully parameterized package of Maple tools has been developed and used to visualize singularities and their consequences.

scholarly journals Sensitivity Analysis of the Orthoglide: A Three-DOF Translational Parallel Kinematic Machine

2005 ◽  
Vol 128 (2) ◽  
pp. 392-402 ◽  
Author(s):  
Stéphane Caro ◽  
Philippe Wenger ◽  
Fouad Bennis ◽  
Damien Chablat
Keyword(s):  
Design Parameters ◽  
Analysis Method ◽  
Parallel Kinematic Machine ◽  
Vector Method ◽  
End Effector ◽  
Singular Configurations ◽  
Parallel Kinematic ◽  
Position And Orientation ◽  
The One ◽  
Three Degree Of Freedom

In this paper, two complementary methods are introduced to analyze the sensitivity of a three-degree-of-freedom (3-DOF) translational parallel kinematic machine (PKM) with orthogonal linear joints: the Orthoglide. Although these methods are applied to a particular PKM, they can be readily applied to 3-DOF Delta-Linear PKM such as ones with their linear joints parallel instead of orthogonal. On the one hand, a linkage kinematic analysis method is proposed to have a rough idea of the influence of the length variations of the manipulator on the location of its end-effector. On the other hand, a differential vector method is used to study the influence of the length and angular variations in the parts of the manipulator on the position and orientation of its end-effector. Besides, this method takes into account the variations in the parallelograms. It turns out that variations in the design parameters of the same type from one leg to another have the same effect on the position of the end-effector. Moreover, the sensitivity of its pose to geometric variations is a minimum in the kinematic isotropic configuration of the manipulator. On the contrary, this sensitivity approaches its maximum close to the kinematic singular configurations of the manipulator.

Geometric Interpretation of Singular Configurations of a Class of Parallel Manipulators

2011 ◽  
Author(s):  
Xianwen Kong ◽  
Jingjun Yu ◽  
Cle´ment Gosselin
Keyword(s):  
Kinematic Chain ◽  
Parallel Manipulators ◽  
Singularity Analysis ◽  
Geometric Interpretation ◽  
Spherical Joint ◽  
Kinematic Singularity ◽  
Geometric Characteristics ◽  
Singular Configurations ◽  
Parallel Kinematic ◽  
Forward Kinematic

This paper proposes an equivalent serial kinematic chain approach to identify the geometric characteristics of singular configurations of a class of parallel manipulators, which can be reduced to a structure composed of three XS and/or SX legs. Here, S and X denote respectively a spherical joint and a one-degree-of-freedom joint or generalized joint. The equivalent serial kinematic chain associated with a parallel kinematic chain composed of two XS legs is first obtained using the concept of reciprocal screws. The forward kinematic singularity (also static singularity) analysis of the parallel manipulators is then reduced to the singularity (stability) analysis of a single-loop structure. Finally, the geometric characteristics of singular configurations of the class of parallel manipulators are obtained with almost no algebraic derivation.

scholarly journals Modelling and Simulation of Machine Tool Prototype with 6DOF Parallel Mechanism in Matlab / Simulink

2019 ◽  
Vol 254 ◽  
pp. 03002 ◽  
Author(s):  
Vladimír Bulej ◽  
Juraj Uríček ◽  
Manfred Eberth ◽  
Ivan Kuric ◽  
Ján Stanček
Keyword(s):  
Machine Tool ◽  
Simulation Model ◽  
Mechanical System ◽  
Parallel Mechanism ◽  
Control Algorithms ◽  
Kinematic Structure ◽  
Matlab Simulink ◽  
Parallel Kinematic ◽  
Functional Blocks ◽  
Functional Prototype

The article deals with the preparation of simulation model of mechanism with parallel kinematic structure called hexapod as an electro-mechanical system in software MATLAB/Simulink. The simulation model is composed from functional blocks represented each part of mechanism’s kinematic structure with certain properties. The results should be used for further simulation of its behaviour as well as for generating of control algorithms for real functional prototype.

Direct Pose Measurement: A Suitable Way to Increase the Accuracy of Parallel Robots?

2007 ◽  
Author(s):  
Christian Munzinger ◽  
Martin Kipfmu¨ller
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Parallel Robots ◽  
Dynamic Parameters ◽  
Parallel Mechanisms ◽  
End Effector ◽  
Parallel Kinematic Machines ◽  
Machine Tool Structures ◽  
Conventional Machine ◽  
Parallel Kinematic

Parallel robots are showing a high potential for the application in machine tools requesting high stiffness and dynamics. Nevertheless, a broad use of parallel mechanisms in machine tools is nowadays avoided by the minor accuracy of parallel kinematic machines compared to conventional machine tool structures, which entails the need for complex calibration algorithms. In this paper, a strategy to avoid the calibration of parallel kinematic machines by rearranging the measurement system to the end effector is presented. Because this rearrangement entails a massive modification of the machine tools control circuit that causes stability problems, first tests of the concept have been carried out via simulation. The focus of these tests was to determine the necessary dynamic parameters of a suitable machine tool’s structure. The results of these tests are used to derive guidelines for the design of a machine tool with direct pose measurement. Finally, a design approach for a suitable machine tool is presented.

Parallel Mechanism and its Application in Design of Machine Tool with Numerical Control

2013 ◽  
Vol 282 ◽  
pp. 74-79 ◽  
Author(s):  
Viera Poppeova ◽  
Vladimir Bulej ◽  
Robert Zahoranský ◽  
Juraj Uríček
Keyword(s):  
Machine Tool ◽  
Parallel Mechanism ◽  
Numerical Control ◽  
Kinematic Structure ◽  
Final Solution ◽  
Risk Of Injury ◽  
Real Risk ◽  
Parallel Kinematic ◽  
Automatic Tool ◽  
And Robotics

This paper describes the design of machine tool based on the mechanism with parallel kinematic structure (PKS) called hexapod. The advantages of mechanisms with PKS predetermine them to the field of machining and robotics. Machine tool is designed like fully automated device contains system for automatic tool and part changing too. There was necessary to solve also a question of operation safety according to the real risk of injury. Some information about the design process, main requirements, the problems and the final solution can be found in this paper.

Mobility Analysis of the 3-UPU Parallel Mechanism Assembled for a Pure Translational Motion

2002 ◽  
Vol 124 (2) ◽  
pp. 259-264 ◽  
Author(s):  
Raffaele Di Gregorio ◽  
Vincenzo Parenti-Castelli
Keyword(s):  
Path Planning ◽  
Parallel Mechanism ◽  
Translational Motion ◽  
Analytic Form ◽  
Geometric Interpretation ◽  
Parallel Mechanisms ◽  
Basic Information ◽  
Mobility Analysis ◽  
Singular Configurations ◽  
Translation Motion

The occurrence of singular configurations in parallel mechanisms must be avoided during motion since the actuators cannot control motion even in the neighborhood of these configurations. As a consequence, the knowledge of the singular configurations of the mechanism is important for control purposes, for singularity-free path planning, and also represents basic information for the synthesis of a desired mechanism workspace free from singularities. In this paper the mobility analysis of the 3-UPU parallel mechanism assembled for obtaining a pure translation motion of the output platform is performed and both translation and rotation singularity loci are presented in analytic form and their geometric interpretation is given.

scholarly journals Sensitivity Analysis of the Orthoglide, a 3-DOF Translational Parallel Kinematic Machine

2004 ◽  
Author(s):  
Ste´phane Caro ◽  
Philippe Wenger ◽  
Fouad Bennis ◽  
Damien Chablat
Keyword(s):  
Sensitivity Analysis ◽  
Kinematic Analysis ◽  
Design Parameters ◽  
Analysis Method ◽  
Parallel Kinematic Machine ◽  
Vector Method ◽  
End Effector ◽  
Singular Configurations ◽  
Parallel Kinematic ◽  
Position And Orientation

This paper presents a sensitivity analysis of the Orthoglide, a 3-DOF translational Parallel Kinematic Machine. Two complementary methods are used to analyze its sensitivity to its dimensional and angular variations. First, a linkage kinematic analysis method is used to have a rough idea of the influence of the dimensional variations on the location of the end-effector, and shows that the variations in design parameters of the same type from one leg to another one have the same influence on the end-effector. However, this method does not allow the designer to know the influence of the variations in the parallelograms. Thus, a differential vector method is used to study the influence of the dimensional and angular variations in the parts of the manipulator, and particularly the variations in the parallelograms, on the position and orientation of the end-effector. It turns out that the isotropic kinematic configuration of the manipulator is the least sensitive one to its geometrical variations, contrary to the closest configurations to its kinematic singular configurations, which are the most sensitive to geometrical variations.

Singularity Analysis and Simulation of 3-PRRR Parallel Mechanism

2014 ◽  
Vol 556-562 ◽  
pp. 1226-1231
Author(s):  
Ya Ya Zhu ◽  
Tie Fu ◽  
Hong Sheng Ding ◽  
Yan Ming Wang ◽  
Yong Jie Wang
Keyword(s):  
Theoretical Basis ◽  
Parallel Mechanism ◽  
Singularity Analysis ◽  
Search Method ◽  
Kinematics Analysis ◽  
Analysis Model ◽  
Vector Method ◽  
Singular Configurations ◽  
Cylindrical Coordinate

A new 3-DOF parallel mechanism is presented and its kinematics analysis model was established based on the vector method. Based on the speed equations of the mechanism, its singular conditions and singular configurations were analyzed systematically. Moreover, a given mechanism’s singularity was simulated by using cylindrical coordinate search method based on its inverse displacement solutions. The results show that the workspace of mechanism with outset chains is much bigger than mechanism with inset chains. The analysis and simulation on singularity provide a theoretical basis for the dimension synthesis and optimization of this kind of parallel mechanism.

Singularity Analysis of 2-DOF Parallel Manipulator

2012 ◽  
Vol 569 ◽  
pp. 589-592
Author(s):  
Jong Gyu Lee ◽  
Sang Ryong Lee ◽  
Choon Young Lee ◽  
Seung Han Yang
Keyword(s):  
Kinematic Analysis ◽  
Parallel Manipulator ◽  
Strong Influence ◽  
Orientation Angle ◽  
Singularity Analysis ◽  
End Effector ◽  
Jacobian Matrices ◽  
Singular Configurations ◽  
Workspace Boundary

The end-effector of 2-DOF parallel manipulator has an orientation. Jacobian matrices are obtained by kinematic analysis. The singular configurations of the manipulator are found using these matrices and the certain characteristic of these configurations is investigated. With the result from simulation, we found that these configurations happened to workspace-interior as well as workspace-boundary and the orientation angle of the end-effector exerted a strong influence on the singularity of the manipulator.

Singularity Analysis of Large Workspace 3RRRS Parallel Mechanism Using Line Geometry and Linear Complex Approximation

2010 ◽  
Vol 3 (1) ◽  
Author(s):  
Alon Wolf ◽  
Daniel Glozman
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Screw Theory ◽  
Singularity Analysis ◽  
Community Research ◽  
Parallel Mechanisms ◽  
Line Geometry ◽  
Equilibrium Equations ◽  
Six Degrees Of Freedom ◽  
Singular Configurations

During the last 15 years, parallel mechanisms (robots) have become more and more popular among the robotics and mechanism community. Research done in this field revealed the significant advantage of these mechanisms for several specific tasks, such as those that require high rigidity, low inertia of the mechanism, and/or high accuracy. Consequently, parallel mechanisms have been widely investigated in the last few years. There are tens of proposed structures for parallel mechanisms, with some capable of six degrees of freedom and some less (normally three degrees of freedom). One of the major drawbacks of parallel mechanisms is their relatively limited workspace and their behavior near or at singular configurations. In this paper, we analyze the kinematics of a new architecture for a six degrees of freedom parallel mechanism composed of three identical kinematic limbs: revolute-revolute-revolute-spherical. We solve the inverse and show the forward kinematics of the mechanism and then use the screw theory to develop the Jacobian matrix of the manipulator. We demonstrate how to use screw and line geometry tools for the singularity analysis of the mechanism. Both Jacobian matrices developed by using screw theory and static equilibrium equations are similar. Forward and inverse kinematic solutions are given and solved, and the singularity map of the mechanism was generated. We then demonstrate and analyze three representative singular configurations of the mechanism. Finally, we generate the singularity-free workspace of the mechanism.

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