Robot 6-Axis/de

Übersicht
This article is about bringing a standard 6-Axis industry robot into FreeCAD for simulation in the Robot Workbench

The description follows the Denavit-Hartenberg Parameter system, as also described in John J. Craigs book "Introduction to Robotics".

Kinematik
This leads to following table:

Since the Kuka robots do not have all axis to 0 in the drawn L-Position, we have to change axis 2 & 3 by 90°.

In the data sheet we find additional information about the axis:



That leads to this complete table:

Visuelle Darstellung
FreeCAD kann aus der Kinematik Tabelle ein grobes Bild erzeugen. Wenn du aber näher an der Realität sein willst, kannst du eine VRML Datei mit der Roboterform für die Simulation verwenden. Z. B. Kuka liefert für sein Modell VRML Dateien. Die VRML Datei wird bei der Erstellung des spezifischen Roboters in FreeCAD geladen. Damit FreeCAD die Achsen bewegen kann, müssen wir die VRML Datei bearbeiten und spezielle Transformationsknoten einfügen, die FreeCAD finden und verändern kann.

Again shown by the example Kuka KR 16. Beginning from line 1:

# # #{ #} Transform {   #rotation 1 0 0 -1.5707963 #scale .001 .001 .001 children [           DEF AOBJ_0001_000_TRAFO Transform {              children [ ... You see this file is exported with a robot simulation software called Tecnomatix. Remove this notice and put in a URL where you get this file from, because Tecnomatix has no copyright in the file content. It's only a converter! First of all we remove the Background node. Then remove the rotation and scale node to get the model to mm and upright Z.
 * 1) VRML V2.0 utf8
 * 1) This VRML97 file was exported using eM-Workplace
 * 2) (c) Tecnomatix Technologies GmbH & Co. KG
 * 3)     Heisenberg-Bogen 1
 * 4)     D-85609 Aschheim-Dornach
 * 5)     GERMANY
 * 1) Background
 * 1)   skyColor   [0.752941 0.752941 0.752941]

Right at the end: ] }  ] }   ] }   ] } #{ #}
 * 1) ROUTE SENS_04_OBJ.rotation_changed TO AXIS_04_OBJ.rotation
 * 2) ROUTE SENS_27_OBJ.rotation_changed TO AXIS_27_OBJ.rotation
 * 3) ROUTE SENS_32_OBJ.rotation_changed TO AXIS_32_OBJ.rotation
 * 4) ROUTE SENS_44_OBJ.rotation_changed TO AXIS_44_OBJ.rotation
 * 5) ROUTE SENS_46_OBJ.rotation_changed TO AXIS_46_OBJ.rotation
 * 6) ROUTE SENS_49_OBJ.rotation_changed TO AXIS_49_OBJ.rotation
 * 7) DEF AnySIMTimer TimeSensor
 * 1)   cycleInterval 1.000000
 * 2)   loop          TRUE

Comment out the TimeSensor and the 6 routes. This 6 lines give you a hint where the actual axis of the robot are! First search for "AXIS_04_OBJ" that brings you to that place: ...    Transform { rotation 1 0 0 1.570796 children [ DEF SENS_04_OBJ-0001 CylinderSensor {           diskAngle 1.570796 minAngle -3.228859 maxAngle 3.228859 offset   0.000000 }      DEF FREECAD_AXIS1 Transform { rotation 0 1 0 0 children [ DEF AXIS_04_OBJ-0001 Transform {        children [        Transform { rotation 1 0 0 -1.570796 children [ DEF AOBJ_0001_003_TRAFO Transform {              rotation 1.000000 0.000000 0.000000 3.141593 translation -600.000000 500.000000 300.000000 children [ ... You have to insert exactly above the definition of this node the line "DEF FREECAD_AXIS1 Transform { rotation 0 1 0 0 children [" which is the anchor for FreeCAD to move the axis.

Now do the same for FREECAD_AXIS2,FREECAD_AXIS3,FREECAD_AXIS4,FREECAD_AXIS5 and FREECAD_AXIS6. Don't forget the closing brackets at the end of the file and you're done!

You can load the VRML by instantiating the robot: App.activeDocument.addObject("Robot::RobotObject","Robot") App.activeDocument.Robot.RobotVrmlFile = "C:/_Projekte/FreeCAD0.9_build/mod/Robot/Lib/Kuka/kr16.wrl" which should give you that result:

KR 210
Data sheet

KR 500
Data sheet