Difference between revisions of "VRML Preparation for Robot Simulation/fr"

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= VRML_Preparation_for_Robot_Simulation/fr =
+
This tutorial explains how to use FreeCAD and the Robot Simulation Workbench to simulate the motions of 6-axis serial robot. '''The tutorial focuses on the creation of the vrml file''' used as visualization. The base of the vrml file is a FreeCAD model. The version of FreeCAD used is 0.11.4252ppa1 on Ubuntu 32bit.
__TOC__
 
  
Ce tutoriel explique comment utiliser FreeCAD et le '''Workbench Simulation Robot''' pour simuler les mouvements de robots sur '''6 axes'''.<br>
+
== Open a file or create one with FreeCAD ==
Le tutoriel se concentre sur la création du fichier '''VRML''' utilisé pour la visualisation. La base du fichier '''VRML''' est un modèle FreeCAD. La version de FreeCAD utilisée est '''0.11.4252ppa1''' sur Ubuntu 32 bits.
+
The tutorial is based on a STEP-file of a Stäubli TX40 (TX40-HB.stp). You can download the file from [https://secure.staubli.com/Intranet_Applications/Robotics/Group/RobDoc.nsf/ea05b3f4b301f597c1256d5f005665e8/bc3707ec036c9f6bc12576c700327958/$FILE/page.html Stäubli]. However, though I still didn't have time to check this, the method should also apply to a model completely made in FreeCAD.
 +
After opening the file, you should obtain this:
  
== Ouvrir un fichier, ou en créer un avec FreeCAD ==
+
[[File:staeubli_step_import.png|1024px]]
  
Le tutoriel est basé sur un '''fichier-STEP''' d'un '''[http://www.staubli.com/fr/robotique/robots-4-et-6-axes/robots-petits-porteurs/tx40/ Stäubli TX40]''', vous pouvez télécharger le fichier [https://secure.staubli.com/Intranet_Applications/Robotics/Group/RobDoc.nsf/ea05b3f4b301f597c1256d5f005665e8/bc3707ec036c9f6bc12576c700327958/$FILE/page.html fichier TX40-HB.stp], la méthode, devrait également s'appliquer à un modèle entièrement réalisé dans FreeCAD, cependant, je n'ai pas encore eu le temps de vérifier ce point.<br>
+
Notice, that on import, the robot is made of 8 shapes, directly on the root of the document tree. The structure of the exported vrml file may change if groups are used. The shapes are ordered from the base to the tool. The last shape contains the axes of rotations of all robot axes. The correlation shape name – part name is given by (as for now (March 2011) FreeCAD doesn't import the names included in STEP files):
Après l'ouverture du fichier, vous devriez obtenir ceci :
 
<br><br>
 
[[File:staeubli_step_import.png]]
 
<br><br>
 
On notera que pour l'importation, le robot est composé de 8 formes, directement sur la racine de l'arbre du document.<br>
 
La structure du fichier '''VRML''' exporté peut changer si des groupes sont utilisés. Les formes sont commandées à partir de la base de l'outil.<br>
 
La dernière forme contient les axes de rotation de tous les axes du robot.<br>
 
Le nom de forme de corrélation, le nom de la pièce est donné (pour l'instant (Mars 2011) par FreeCAD, FreeCAD n'importe pas encore les noms inclus dans les fichiers STEP) :
 
  
 
{| class="wikitable"
 
{| class="wikitable"
Line 47: Line 39:
 
|}
 
|}
  
Pour cette importation, changez le "Mode d'affichage" de chaque forme, à l'exception '''TX40_HB007''', de "'''lisser'''" les lignes en "'''Ombrage'''" pour l'exportation '''VRML''' pour faire bonne figure. J'ai aussi changé les couleurs de '''[245, 196, 0]''' et '''[204, 204, 204]''' afin de mieux correspondre au jaune Stäubli.<br>
+
For this import, change the “Display Mode” of each shape, TX40_HB007 excepted, from “Flat Lines” to “Shaded” for the vrml export to look good. I also changed the colors to [245, 196, 0] and [204, 204, 204] to better correspond to Stäubli's yellow. Hide TX40_HB007 because it contains the axes of all joints and cannot be taken apart.
Masquer '''TX40_HB007''' car il contient les axes de tous les joints et ne peut pas être démonté.
 
  
== Mesure des caractéristiques géométriques ==
+
== Measure geometric characteristics ==
 +
In order to build the Denavit-Hartenberg table (see [http://www.freecadweb.org/wiki/index.php?title=6-Axis_Robot 6-Axis Robot]) and prepare the vrml file, you need to get characteristics of the robot. For now, the measurement tool of FreeCAD is not ready, you can use the axes included in TX40_HB007 (the co-ordinates are indicated on the bottom left when you point an object with the mouse) or you have to use the Python console to get some information about the geometry. Note that the DH-table is only required if you need to use the inverse kinematics, i.e.  get the Cartesian coordinates or drive the robot with Cartesian coordinates.
 +
The DH-table for this robot is the following (mm, deg and deg/s):
  
Afin de construire la table [http://fr.wikipedia.org/wiki/Denavit-Hartenberg Denavit-Hartenberg] (voir [[6-Axis_Robot/fr|6-Axis_Robot]] ) et de préparer le fichier [http://fr.wikipedia.org/wiki/Virtual_Reality_Markup_Language VRML], que vous avez besoin pour obtenir des caractéristiques du Robot. Pour l'instant, l'outil de mesure de FreeCAD n'est pas prêt, vous pouvez utiliser les axes inclus dans '''TX40_HB007''' (les coordonnées sont indiquées en bas à gauche lorsque vous pointez un objet avec la souris) ou vous devez utiliser la [[Introduction_to_python/fr|console Python]] pour obtenir des informations sur la forme géométrique.<br>
 
Notez que, le '''DH-tableau''' n'est nécessaire que si vous avez besoin d'utiliser la cinématique inverse, c'est à dire obtenir les coordonnées cartésiennes ou de commander le robot en coordonnées cartésiennes.<br>
 
La '''DH-table''' pour ce robot est le suivant '''(mm, degrés et deg/s)''' :
 
<br>
 
 
{| class="wikitable"
 
{| class="wikitable"
 
|-
 
|-
Line 121: Line 110:
 
| 1575
 
| 1575
 
|}
 
|}
<br>
+
 
Le fichier '''csv''' est :
+
The csv file is then:
  
 
  a  , alpha, d  , theta, rotDir, maxAngle, minAngle, AxisVelocity
 
  a  , alpha, d  , theta, rotDir, maxAngle, minAngle, AxisVelocity
Line 132: Line 121:
 
  0  ,    0,  65,    0,      1,      270,    -270, 1575
 
  0  ,    0,  65,    0,      1,      270,    -270, 1575
  
== Exporter en VRML ==
+
== Export to vrml ==
 
+
Export the document to a vrml file. The structure of the vrml file is the following:
Exporter le document dans un fichier VRML.<br>
+
<syntaxhighlight>
La structure du fichier VRML est la suivante :
 
  
 
  #VRML V2.0 utf8
 
  #VRML V2.0 utf8
Line 187: Line 175:
 
   
 
   
 
  }
 
  }
 +
</syntaxhighlight>
  
Vous pouvez remarquer que nous avons 8 groupes indépendants, correspondants aux 8 formes.
+
You can notice that we have 8 independent groups corresponding to the 8 shapes.
  
== Préparation du dossier de vrml ==
+
== Preparation of the vrml file ==
 +
All shapes in the vrml file are expressed in the base frame, independently from each other. For the Robot Simulation Workbench, we need to create a structure where a movement of a shape induces a movement of all shapes situated afterwards in the structure. The placement of the shapes will be relative to the preceding shape, so we need to include some translations from the absolute reference system to the relative one. The translations are described in the following picture:
  
Toutes les formes dans le fichier '''vrml''' sont exprimés dans le cadre de base, indépendamment les uns des autres. Pour le '''Workbench Simulation Robot''', nous avons besoin de créer une structure où, un mouvement de formes induit un mouvement de toutes les formes qui se trouveront ensuite dans la structure. Le placement des formes sera relatif à la forme précédente, nous avons donc besoin d'inclure quelques modifications à partir du système de référence absolue vers celui relatif.<br>
 
Les traductions sont décrites dans le tableau suivant :
 
<br><br>
 
 
[[Image:staeubli_important_points.png]]
 
[[Image:staeubli_important_points.png]]
<br><br>
+
 
 
With
 
With
 
: A=(0, 0, 168)
 
: A=(0, 0, 168)
Line 204: Line 191:
 
: E=(0, 35, 770)
 
: E=(0, 35, 770)
 
: F=(0, 35, 835).
 
: F=(0, 35, 835).
<br>
 
Prenons l'exemple de l'axe '''4''' entre le coude et avant-bras, située à '''D = (xd, yd, zd)'''.<br>
 
Le point d'ancrage pour l'axe de FreeCAD est :
 
  
 +
Let's take the example of axis 4 between ELBOW and FOREARM, situated at D=(xd, yd, zd). The anchor for the FreeCAD axis is
 +
<syntaxhighlight>
 
  "DEF FREECAD_AXIS4 Transform { rotation 0 1 0 0 children ["
 
  "DEF FREECAD_AXIS4 Transform { rotation 0 1 0 0 children ["
 
+
</syntaxhighlight>
Cela correspond à une rotation autour de l'axe '''y'''. Dans le modèle CAO, la rotation se fait sur l'axe '''z'''. Ainsi, nous avons besoin d'une rotation autour de l'axe '''x''' de '''<math>\pi</math>''' avant la définition des axes de FreeCAD et de '''-<math>\pi</math>''' après. En outre, une traduction de '''(-xd, yd-,-zd)''' est nécessaire juste avant le groupe correspondant à la définition de l'avant bras, et de l'exprimer dans le cadre de référence centré par rapport à '''D'''.<br>
+
This corresponds to a rotation about the y-axis. In the CAD model, the rotation is about the z-axis. Thus, we need to a rotation about the x-axis of <math>\pi</math> before the FreeCAD axis definition and of <math>-\pi</math> after it. Also, a translation of (-xd, -yd, -zd) is needed just before the Group corresponding to the definition of FOREARM to express it in the relative reference frame centered at D. This means that a translation of (xd, yd, zd) must be inserted before the first rotation.
Cela signifie que la traduction de '''(xd, yd, zd)''' doit être insérée avant la première rotation.<br>
+
At the end, the vrml-file from the definition of ELBOW to the definition of FOREARM looks like this:
A la fin, le '''fichier vrml''' à partir de la définition du '''COUDE''' (ELBOW) vers la définition de l''''avant bras''' (FOREARM) ressemble à ceci :
+
<syntaxhighlight>
 
 
 
       # ELBOW
 
       # ELBOW
 
       Group {
 
       Group {
Line 236: Line 221:
 
    
 
    
 
       },
 
       },
 +
</syntaxhighlight>
 
    
 
    
A la fin du document, les crochets de fermeture appropriés doivent être insérés : '''"]}}}}"''', pour chacun des 6 axes.<br>
+
At the end of the document, the appropriate closing brackets must be inserted: “  ]}}}},” for each of the 6 axes. Eventually, the document looks like this (I don't know if I can link the file here because of copyrights):
Finalement, le document ressemble à ceci (ici, je ne sais pas si je peux établir un lien avec le fichier, à cause des droits d'auteur (copyrights)):
+
<syntaxhighlight>
 
 
 
  #VRML V2.0 utf8
 
  #VRML V2.0 utf8
 
    
 
    
Line 368: Line 353:
 
   }
 
   }
 
  }
 
  }
 
+
</syntaxhighlight>
Voici un '''patch''' pour obtenir un fichier '''vrml''' convenant à la simulation du robot :
+
Here is a patch to obtain the vrml file suitable for robot simulation:
 +
<syntaxhighlight>
  
 
  7a8
 
  7a8
Line 463: Line 449:
 
  >      ]
 
  >      ]
  
 +
</syntaxhighlight>
 +
[[Category:Tutorials]]
  
 
+
{{clear}}
{{languages/fr | {{en|VRML_Preparation_for_Robot_Simulation}} {{es|VRML_Preparation_for_Robot_Simulation/es}} {{it|VRML_Preparation_for_Robot_Simulation/it}} }}
+
<languages/>
 
 
[[Category:Tutorials/fr]]
 

Revision as of 19:10, 12 May 2014

This tutorial explains how to use FreeCAD and the Robot Simulation Workbench to simulate the motions of 6-axis serial robot. The tutorial focuses on the creation of the vrml file used as visualization. The base of the vrml file is a FreeCAD model. The version of FreeCAD used is 0.11.4252ppa1 on Ubuntu 32bit.

Open a file or create one with FreeCAD

The tutorial is based on a STEP-file of a Stäubli TX40 (TX40-HB.stp). You can download the file from Stäubli. However, though I still didn't have time to check this, the method should also apply to a model completely made in FreeCAD. After opening the file, you should obtain this:

Staeubli step import.png

Notice, that on import, the robot is made of 8 shapes, directly on the root of the document tree. The structure of the exported vrml file may change if groups are used. The shapes are ordered from the base to the tool. The last shape contains the axes of rotations of all robot axes. The correlation shape name – part name is given by (as for now (March 2011) FreeCAD doesn't import the names included in STEP files):

FreeCAD name STEP name
TX40_HB HORIZONTAL BASE CABLE OUTLET
TX40_HB001 SHOULDER
TX40_HB002 ARM
TX40_HB003 ELBOW
TX40_HB004 FOREARM
TX40_HB005 WRIST
TX40_HB006 TOOL FLANGE
TX40_HB007 ?

For this import, change the “Display Mode” of each shape, TX40_HB007 excepted, from “Flat Lines” to “Shaded” for the vrml export to look good. I also changed the colors to [245, 196, 0] and [204, 204, 204] to better correspond to Stäubli's yellow. Hide TX40_HB007 because it contains the axes of all joints and cannot be taken apart.

Measure geometric characteristics

In order to build the Denavit-Hartenberg table (see 6-Axis Robot) and prepare the vrml file, you need to get characteristics of the robot. For now, the measurement tool of FreeCAD is not ready, you can use the axes included in TX40_HB007 (the co-ordinates are indicated on the bottom left when you point an object with the mouse) or you have to use the Python console to get some information about the geometry. Note that the DH-table is only required if you need to use the inverse kinematics, i.e. get the Cartesian coordinates or drive the robot with Cartesian coordinates. The DH-table for this robot is the following (mm, deg and deg/s):

i d θ r α θmin θmax Axis velocity
1 320 q1 0 -90 -180 180 555
2 35 q2 - 90 225 0 -125 125 475
3 0 q3 + 90 0 90 -138 138 585
4 225 q4 0 -90 -270 270 1035
5 0 q5 0 90 -120 133.5 1135
6 65 q6 0 0 -270 270 1575

The csv file is then:

a  , alpha, d  , theta, rotDir, maxAngle, minAngle, AxisVelocity
0  ,   -90, 320,     0,      1,      180,     -180, 555
225,     0,  35,   -90,      1,      125,     -125, 475
0  ,    90,   0,    90,      1,      138,     -138, 585
0  ,   -90, 225,     0,      1,      270,     -270, 1035
0  ,    90,   0,     0,      1,    133.5,     -120, 1135
0  ,     0,  65,     0,      1,      270,     -270, 1575

Export to vrml

Export the document to a vrml file. The structure of the vrml file is the following:

 #VRML V2.0 utf8
 
 
 Group {
   children 
     Group {
       children [ 
         Group {
         …
 
         },
           
         Group {
         …
 
         },
           
         Group {
         …
 
         },
           
         Group {
         …
 
         },
           
         Group {
         …
 
         },
           
         Group {
         …
 
         },
           
         Group {
         …
 
         },
           
         Group {
         …
 
         } ]
 
     }
 
 }

You can notice that we have 8 independent groups corresponding to the 8 shapes.

Preparation of the vrml file

All shapes in the vrml file are expressed in the base frame, independently from each other. For the Robot Simulation Workbench, we need to create a structure where a movement of a shape induces a movement of all shapes situated afterwards in the structure. The placement of the shapes will be relative to the preceding shape, so we need to include some translations from the absolute reference system to the relative one. The translations are described in the following picture:

Staeubli important points.png

With

A=(0, 0, 168)
B=(0, 107.8, 320)
C=(0, 104.15, 545)
D=(0, 35, 601)
E=(0, 35, 770)
F=(0, 35, 835).

Let's take the example of axis 4 between ELBOW and FOREARM, situated at D=(xd, yd, zd). The anchor for the FreeCAD axis is

 "DEF FREECAD_AXIS4 Transform { rotation 0 1 0 0 children ["

This corresponds to a rotation about the y-axis. In the CAD model, the rotation is about the z-axis. Thus, we need to a rotation about the x-axis of before the FreeCAD axis definition and of after it. Also, a translation of (-xd, -yd, -zd) is needed just before the Group corresponding to the definition of FOREARM to express it in the relative reference frame centered at D. This means that a translation of (xd, yd, zd) must be inserted before the first rotation. At the end, the vrml-file from the definition of ELBOW to the definition of FOREARM looks like this:

       # ELBOW
       Group {
         … here comes the unmodified definition of ELBOW
   
       },
         
       Transform {
         translation 0 35 601
         rotation 1 0 0 1.5707963
         children
           DEF FREECAD_AXIS4 Transform { rotation 0 1 0 0 children
             Transform {
               rotation 1 0 0 -1.5707963
               children
                 Transform {
                   translation 0 -35 -601
                   children [
       # FOREARM  
       Group {
         ... here comes the unmodified definition of FOREARM
   
       },

At the end of the document, the appropriate closing brackets must be inserted: “ ]}}}},” for each of the 6 axes. Eventually, the document looks like this (I don't know if I can link the file here because of copyrights):

 #VRML V2.0 utf8
   
   
 Group {
   children
   Group {
     children [ 
       # HORIZONTAL BASE CABLE OUTLET 
       Group {
           ... here comes the unmodified definition of HORIZONTAL BASE CABLE OUTLET
    
       },
         
       Transform {
         translation 0 0 168
         rotation 1 0 0 1.5707963
         children
           DEF FREECAD_AXIS1 Transform { rotation 0 1 0 0 children
             Transform {
               rotation 1 0 0 -1.5707963
               children
                 Transform {
                   translation 0 0 -168
                   children [
       # SHOULDER
       Group {
           ... here comes the unmodified definition of SHOULDER 
   
       },
         
       Transform {
         translation 0 107.8 320
         #rotation 0 0 1 0
         children
           DEF FREECAD_AXIS2 Transform { rotation 0 1 0 0 children
             Transform {
               #rotation 0 0 1 0
               children
                 Transform {
                   translation 0 -107.8 -320
                   children [
       # ARM  
       Group {
           ... here comes the unmodified definition of ARM 
   
       },
         
       Transform {
         translation 0 104.15 545
         #rotation 0 0 1 0
         children
           DEF FREECAD_AXIS3 Transform { rotation 0 1 0 0 children
             Transform {
               #rotation 0 0 1 0
               children
                 Transform {
                   translation 0 -104.15 -545
                   children [
       # ELBOW
       Group {
           ... here comes the unmodified definition of ELBOW
   
       },
         
       Transform {
         translation 0 35 601
         rotation 1 0 0 1.5707963
         children
           DEF FREECAD_AXIS4 Transform { rotation 0 1 0 0 children
             Transform {
               rotation 1 0 0 -1.5707963
               children
                 Transform {
                   translation 0 -35 -601
                   children [
       # FOREARM  
       Group {
           ... here comes the unmodified definition of FOREARM
   
       },
         
       Transform {
         translation 0 35 770
         #rotation 0 0 1 0
         children
           DEF FREECAD_AXIS5 Transform { rotation 0 1 0 0 children
             Transform {
               #rotation 0 0 1 0
               children
                 Transform {
                   translation 0 -35 -770
                   children [
       # WRIST
       Group {
           ... here comes the unmodified definition of WRIST
   
       },
         
       Transform {
         translation 0 35 835
         rotation 1 0 0 1.5707963
         children
           DEF FREECAD_AXIS6 Transform { rotation 0 1 0 0 children
             Transform {
               rotation 1 0 0 -1.5707963
               children
                 Transform {
                   translation 0 -35 -835
                   children [
       # TOOL FLANGE
       Group {
           ... here comes the unmodified definition of TOOL FRAME
   
       },
         
       Group {
           ... here comes the unmodified definition of TX40_HB007
   
       } # "]" was deleted from this line
     ]}}}},
     ]}}}},
     ]}}}},
     ]}}}},
     ]}}}},
     ]}}}},
     ] # this is the "]" deleted from the line above
   }
 }

Here is a patch to obtain the vrml file suitable for robot simulation:

 7a8
 >         # HORIZONTAL BASE CABLE OUTLET 
 95968a95970,95981
 >         Transform {
 >           translation 0 0 168
 >           rotation 1 0 0 1.5707963
 >           children
 >             DEF FREECAD_AXIS1 Transform { rotation 0 1 0 0 children
 >               Transform {
 >                 rotation 1 0 0 -1.5707963
 >                 children
 >                   Transform {
 >                     translation 0 0 -168
 >                     children [
 >         # SHOULDER
 128428a128442,128453
 >         Transform {
 >           translation 0 107.8 320
 >           #rotation 0 0 1 0
 >           children
 >             DEF FREECAD_AXIS2 Transform { rotation 0 1 0 0 children
 >               Transform {
 >                 #rotation 0 0 1 0
 >                 children
 >                   Transform {
 >                     translation 0 -107.8 -320
 >                     children [
 >         # ARM  
 206503a206529,206540
 >         Transform {
 >           translation 0 104.15 545
 >           #rotation 0 0 1 0
 >           children
 >             DEF FREECAD_AXIS3 Transform { rotation 0 1 0 0 children
 >               Transform {
 >                 #rotation 0 0 1 0
 >                 children
 >                   Transform {
 >                     translation 0 -104.15 -545
 >                     children [
 >         # ELBOW
 267111a267149,267160
 >         Transform {
 >           translation 0 35 601
 >           rotation 1 0 0 1.5707963
 >           children
 >             DEF FREECAD_AXIS4 Transform { rotation 0 1 0 0 children
 >               Transform {
 >                 rotation 1 0 0 -1.5707963
 >                 children
 >                   Transform {
 >                     translation 0 -35 -601
 >                     children [
 >         # FOREARM  
 417854a417904,417915
 >         Transform {
 >           translation 0 35 770
 >           #rotation 0 0 1 0
 >           children
 >             DEF FREECAD_AXIS5 Transform { rotation 0 1 0 0 children
 >               Transform {
 >                 #rotation 0 0 1 0
 >                 children
 >                   Transform {
 >                     translation 0 -35 -770
 >                     children [
 >         # WRIST
 422053a422115,422126
 >         Transform {
 >           translation 0 35 835
 >           rotation 1 0 0 1.5707963
 >           children
 >             DEF FREECAD_AXIS6 Transform { rotation 0 1 0 0 children
 >               Transform {
 >                 rotation 1 0 0 -1.5707963
 >                 children
 >                   Transform {
 >                     translation 0 -35 -835
 >                     children [
 >         # TOOL FLANGE
 435627c435700,435707
 <         } ]
 ---
 >         } 
 >       ]}}}},
 >       ]}}}},
 >       ]}}}},
 >       ]}}}},
 >       ]}}}},
 >       ]}}}},
 >       ]
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