An Efficient Algorithm for the Graphical Representation of the Three-Dimensional Workspace of Parallel Manipulators

1992 ◽  
Author(s):  
Clément M. Gosselin ◽  
Eric Lavoie ◽  
Pierre Toutant
Keyword(s):  
Graphical Representation ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Dimensional Representation ◽  
Efficient Procedure ◽  
Three Dimensional Representation ◽  
The Subject ◽  
Six Degree Of Freedom ◽  
Analytical Expressions

Abstract This paper presents an algorithm for the graphical representation of the three-dimensional workspace of six-degree-of-freedom parallel manipulators. In fact, the algorithm introduced here follows from previous work on the subject (Gosselin 1990). In the latter reference, an algorithm was developed to obtain analytical expressions of the boundaries of the workspace. However, the method was applicable to two-dimensional sections of the workspace only. Therefore, a three-dimensional representation of the workspace, i.e., the set of positions attainable with a given orientation of the platform, could only be obtained by discretization. The algorithm introduced here involves the determination of analytical expressions of the boundaries of the three-dimensional workspace. Hence, it results in a very efficient procedure which can be performed interactively, in a context of CAD. The algorithm is described in detail in this paper. Examples of results that have been obtained with this algorithm are also presented.

Determination of the Workspace of 6-DOF Parallel Manipulators

1989 ◽  
Author(s):  
C. Gosselin
Keyword(s):  
Parallel Manipulator ◽  
Graphical Representation ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Geometrical Properties ◽  
Cartesian Space ◽  
Six Degree Of Freedom

Abstract This paper presents an algorithm for the determination of the workspace of parallel manipulators. The method described here, which is based on geometrical properties of the workspace, leads to a simple graphical representation of the regions of the three-dimensional Cartesian space that are attainable by the manipulator with a given orientation of the platform. Moreover, the volume of the workspace can be easily computed by performing an integration on its boundary, which is obtained from the algorithm. Examples are included to illustrate the application of the method to a six-degree-of-freedom fully-parallel manipulator.

Determination of the Workspace of 6-DOF Parallel Manipulators

1990 ◽  
Vol 112 (3) ◽  
pp. 331-336 ◽  
Author(s):  
C. Gosselin
Keyword(s):  
Parallel Manipulator ◽  
Graphical Representation ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Geometrical Properties ◽  
Cartesian Space ◽  
Six Degree Of Freedom

This paper presents an algorithm for the determination of the workspace of parallel manipulators. The method described here, which is based on geometrical properties of the workspace, leads to a simple graphical representation of the regions of the three-dimensional Cartesian space that are attainable by the manipulator with a given orientation of the platform. Moreover, the volume of the workspace can be easily computed by performing an integration in its boundary, which is obtained from the algorithm. Examples are included to illustrate the application of the method to a six-degree-of-freedom fully parallel manipulator.

Determination of the Workspace of a Three-Degrees-of-Freedom Parallel Manipulator Using a Three-Dimensional Computer-Aided-Design Software Package and the Concept of Virtual Chains1

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Andrew Johnson ◽  
Xianwen Kong ◽  
James Ritchie
Keyword(s):  
Computer Aided Design ◽  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Graphical Representation ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Workspace Analysis ◽  
Computer Aided ◽  
Aided Design

The determination of workspace is an essential step in the development of parallel manipulators. By extending the virtual-chain (VC) approach to the type synthesis of parallel manipulators, this technical brief proposes a VC approach to the workspace analysis of parallel manipulators. This method is first outlined before being illustrated by the production of a three-dimensional (3D) computer-aided-design (CAD) model of a 3-RPS parallel manipulator and evaluating it for the workspace of the manipulator. Here, R, P and S denote revolute, prismatic and spherical joints respectively. The VC represents the motion capability of moving platform of a manipulator and is shown to be very useful in the production of a graphical representation of the workspace. Using this approach, the link interferences and certain transmission indices can be easily taken into consideration in determining the workspace of a parallel manipulator.

Determination of the Singularity Loci of Spherical Three-Degree-of-Freedom Parallel Manipularors

1992 ◽  
Author(s):  
Clément M. Gosselin ◽  
Jaouad Sefrioui
Keyword(s):  
Graphical Representation ◽  
Jacobian Matrix ◽  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
End Effector ◽  
Cartesian Space ◽  
Singularity Locus ◽  
Three Degree Of Freedom ◽  
Analytical Expressions

Abstract In this paper, an algorithm for the determination of the singularity loci of spherical three-degree-of-freedom parallel manipulators with prismatic atuators is presented. These singularity loci, which are obtained as curves or surfaces in the Cartesian space, are of great interest in the context of kinematic design. Indeed, it has been shown elsewhere that parallel manipulators lead to a special type of singularity which is located inside the Cartesian workspace and for which the end-effector becomes uncontrollable. It is therfore important to be able to identify the configurations associated with theses singularities. The algorithm presented is based on analytical expressions of the determinant of a Jacobian matrix, a quantity that is known to vanish in the singular configurations. A general spherical three-degree-of-freedom parallel manipulator with prismatic actuators is first studied. Then, several particular designs are investigated. For each case, an analytical expression of the singularity locus is derived. A graphical representation in the Cartesian space is then obtained.

Determination of the Workspace of Parallel Manipulators Using a CAD Software and the Concept of Virtual Chains

2013 ◽  
Author(s):  
Andrew Johnson ◽  
Xianwen Kong
Keyword(s):  
Parallel Manipulator ◽  
Graphical Representation ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Singularity Analysis ◽  
Parallel Robots ◽  
Performance Indices ◽  
Workspace Analysis ◽  
Static Calculation

Development of a new parallel manipulator can be very time consuming due to the traditional method of producing kinematic, dynamic and static calculation models and then evaluating them to determine aspects of the manipulator’s performance indices such as the mechanism’s workspace and singularity analysis. By extending the virtual chain approach to the type synthesis of parallel manipulators, this paper proposes a virtual-chain approach to the workspace analysis of parallel manipulators. This method is illustrated by producing and evaluating the workspace of several parallel robots including the well known DELTA robot by utilising the three-dimensional CAD software SolidWorks to produce a virtual prototype of a manipulator with an embedded virtual chain. The virtual chain represents the motion pattern of a manipulator’s end-effector and is very useful in the production of a graphical representation of the workspace of the manipulator. Using this approach, the link interferences and transmission indices can be easily taken into consideration in determining the workspace of a parallel manipulator.

Revealing gross three-dimensional structure in the SEM

1987 ◽  
Vol 45 ◽  
pp. 656-657
Author(s):  
Sterling P. Newberry
Keyword(s):  
Freeze Drying ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Small Object ◽  
Final Solution ◽  
Dimensional Representation ◽  
X Ray ◽  
Three Dimensional Representation ◽  
Freeze Dried ◽  
Critical Point Drying

The beautiful three dimensional representation of small object surfaces by the SEM leads one to search for ways to open up the sample and look inside. Could this be the answer to a better microscopy for gross biological 3-D structure? We know from X-Ray microscope images that Freeze Drying and Critical Point Drying give promise of adequately preserving gross structure. Can we slice such preparations open for SEM inspection? In general these preparations crush more readily than they slice. Russell and Dagihlian got around the problem by “deembedding” a section before imaging. This some what defeats the advantages of direct dry preparation, thus we are reluctant to accept it as the final solution to our problem. Alternatively, consider fig 1 wherein a freeze dried onion root has a window cut in its surface by a micromanipulator during observation in the SEM.

scholarly journals Structured-light 3D scanning of exhibited historical clothing—a first-ever methodical trial and its results

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Jerzy Montusiewicz ◽  
Marek Miłosz ◽  
Jacek Kęsik ◽  
Kamil Żyła
Keyword(s):  
Cultural Heritage ◽  
Information Technologies ◽  
Structured Light ◽  
Three Dimensional ◽  
3D Models ◽  
3D Scanning ◽  
Dimensional Representation ◽  
3D Scanner ◽  
Three Dimensional Representation ◽  
3D Scanners

AbstractHistorical costumes are part of cultural heritage. Unlike architectural monuments, they are very fragile, which exacerbates the problems of their protection and popularisation. A big help in this can be the digitisation of their appearance, preferably using modern techniques of three-dimensional representation (3D). The article presents the results of the search for examples and methodologies of implementing 3D scanning of exhibited historical clothes as well as the attendant problems. From a review of scientific literature it turns out that so far practically no one in the world has made any methodical attempts at scanning historical clothes using structured-light 3D scanners (SLS) and developing an appropriate methodology. The vast majority of methods for creating 3D models of clothes used photogrammetry and 3D modelling software. Therefore, an innovative approach was proposed to the problem of creating 3D models of exhibited historical clothes through their digitalisation by means of a 3D scanner using structural light technology. A proposal for the methodology of this process and concrete examples of its implementation and results are presented. The problems related to the scanning of 3D historical clothes are also described, as well as a proposal how to solve them or minimise their impact. The implementation of the methodology is presented on the example of scanning elements of the Emir of Bukhara's costume (Uzbekistan) from the end of the nineteenth century, consisting of the gown, turban and shoes. Moreover, the way of using 3D models and information technologies to popularise cultural heritage in the space of digital resources is also discussed.

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