Kuka external axes endless rotation issue

Hello, usually if you wish to do endless rotations with external axes, you have to setup the $AXIS_TYPE parameter to ENDLESS in workvisual.

But BEWARE you also have to check can this KUKA positioner on AXIS 2 do ENDLESS rotations in order that you dont BRAKE any cables by twisting them. According to the datasheet for your positioner you can't do endless motions, but either only +-1800 or +-185 depends if energy supply system is used or not.

In datasheet KP2-SV2600HW is stated that axis 2 motion range is +-1800 degrees without energy supply system, then you must leave parameter to ROTATORY if you didn't make any hardware modifications on axis 2 which would allow to do endless motions.

If energy supply system is used axis 2 can only do +-185 and you can't do more than 1 turn or 370 degrees.

If you have axis without energy supply system according to datasheet, then you can do only max 10 turns according to datasheet(2*1800/360=10) and looking to your picture of the part you want to weld i guess it would be enough to have 10 turns, In that case i would check the software limit switch parameters if they are set to more than +360 in positive direction and less then -360 in negative direction , but change parameters only when you are sure what positioner you have according to datasheet(with or without energy supply system) in order not to brake any cables which may go inside of axis center by twisting them by going beyond 360 degrees.

Quote from Andres Tamla

The problem is that all works fine untill positioner reaches approx 360 degrees then it will reverse resulting a collision.

Show the actual code you're using to drive E2.

Is your E2 configured as Rotary or Endless? The reversal you describe is a typical issue with Endless axes, though it usually happens at 180deg instead of 360. The issue is that a command of +185deg puts the axis at the same physical location as performing -5deg, so the motion planner picks the shorter motion. The normal workaround for this is to use a series of REL moves whose Ex component is always less than 180.

Quote from Andres Tamla

I will try to add more CIRC switches to see if it helps. The main goal is to keep to a minimum number of touch-ups.

The last time when I did spiral continuing welds on endless axis, I had 6 points at 60 degrees, but first start point was for example at 10 degrees (so that i would get 70,130,190,...370,430,etc) and just before the CIRC points in the program, i have had to use $ORI_TYPE=#CONSTANT and $CIRC_TYPE=#PATH in order to remain robot "stationary" and only external axis would be turning during welding. But in my program i have calculated points infront and for each turn new 6 points because robot moves along the spiral center axis.

Here is just sample code, it's not complete solution, but it should give rough idea, here is Z axis of the BASE is aligned with the center spiral AXIS or E1, and changing point values in Z you move along the spiral, and for each revolution new Z values are calculated for one spiral.

In order to use ArcTech functions on calculated points in my project, I have copied the ArcTech functions of ordinary ArcTech inline form in front of calculated points

;LIN start_weld_point 

FOR NR_spirals=1 TO 11

   CALC()

   $ORI_TYPE=#CONSTANT
   $CIRC_TYPE=#PATH
   FOR J=0 TO (6/2-1)
         
         BAS(#TOOL,1)
         BAS(#BASE,17) ; base attached to coupled E1

         $VEL.CP=WELD_SPEED
         $APO.CDIS=1.0

     CIRC C_POS[(2*J)+1],C_POS[(2*J)+2] C_DIS
   ENDFOR

ENDFOR


DEF CALC()

DEG = 60.0
DISTANCE = 12.0  ; lenght of one spiral in Z direction

FOR I=1 TO 6

  ; calculation of points of single spiral

  C_POS[I].X=cos(DEG*I)*spiral_radius
  C_POS[I].Y=sin(DEG*I)*spiral_radius

  C_POS[I].Z=POZ_Z+((DISTANCE/6.0)*I)+(DISTANCE*(NR_spirals-1))

  C_POS[I].A=(-90-(DEG*I))
  C_POS[I].B=0.0
  C_POS[I].C=-90.0
  C_POS[I].E1=DEG*I

ENDFOR

END