hard wired approximation settings

  • hello.


    We have 2 Kuka KR240 r2900 ultra's purchased 18 months apart from Kuka and integrated as CNC with spindle's by the same third party integrator.

    we use PowerMill as out programming software. using pretty much the same Post processor to output our SRC files.

    programming them separately, one will follow programmed toolpaths 100% as programmed and the other will very often approximate a sharp corner with a large radius either leaving material in the job for an internal corner or cutting through the part for an external corner. both robot config files have been checked and both poste files have been checked to no outcome.

    it has both myself and integrator puzzled as he has never come across this issue before in over 100+ robots he has integrated for the same process. no matter what smoothing settings we use in PowerMill the robot does what it wants to. if you run the same program on the older robot it follows the programmed corners as programmed without approximating.

    is there a setting somewhere within the new robot we are both missing??? has KUKA changed something?

    Edited once, last by MalcolmK ().

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  • In your case I would create a KRCDiag for each robot, unzip them than compare using e.g. Windiff or kdiff3. If you could tell us these differences we probably are able to give better advice. So far we only know you have two robots that might be the same. No info on KRC versions, software versions, messages in case of the different behaviour, ...


    Otherwise there could be hundreds of reasons (different tool and base, different load, different settings, ...). Usually KUKA does not change stuff incompatible.

  • what does that mean 'robot does what it wants'?

    is robot following programmed path but fails to do approximation (stops at points)?

    or does it mean that robot goes off path and runs toward some far point, starts reorienting wrist etc?

    post being of the program up to first few points. are you sure $ADVANCE is set to non-zero? how about $APO?

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

  • programmed with Power Mill robot plug in.

    Ptp velocity 20%

    Accel 20%

    Smoothing .1mm

    Advance 3 points.


    We program the robot and tool paths and simulation do as tool path generated by powermill is. But when run on new robot it will sometimes (not all the time) approximate a sharp programmed corner with a 50mm radius. Very noticeable on leadin and rapid moves but also within the actual surface milling as well. But run the same file on our older robot it does not approximate anything at all. Surfave milling is as it should be.

  • In your case I would create a KRCDiag for each robot, unzip them than compare using e.g. Windiff or kdiff3. If you could tell us these differences we probably are able to give better advice. So far we only know you have two robots that might be the same. No info on KRC versions, software versions, messages in case of the different behaviour, ...


    Otherwise there could be hundreds of reasons (different tool and base, different load, different settings, ...). Usually KUKA does not change stuff incompatible.

  • Quote


    But when run on new robot it will sometimes (not all the time) approximate a sharp programmed corner with a 50mm radius.


    And this only happens when you execute for the first time and on the second run through your program behaves as expected or after transferring to a new robot the problem is persistent?


    Sorry I still do not totally understand your problem description. Does the robot not approximate or the robot still approximates but run a different blending path. Any messages in case of the bad behaviour like blending not possible? Did you check logbook what's happening.

  • backlash causing 50mm radius on a path?


    Quote

    programmed with Power Mill robot plug in.

    you mentioned that several times. it provides no info. KRC does not care what editor was used to generate code. it only cares what the code actually looks like.


    Quote

    Ptp velocity 20%

    Accel 20%

    i don't know what that means.... are your points PTP? what Accell? post the actual code


    Quote

    Smoothing .1mm

    i don't know what that means. is this some PowerMill setting or $APO? show the code


    Quote

    Advance 3 points.

    show the code



    Quote

    We program the robot and tool paths and simulation do as tool path generated by powermill is. But when run on new robot it will sometimes (not all the time) approximate a sharp programmed corner with a 50mm radius. Very noticeable on leadin and rapid moves but also within the actual surface milling as well. But run the same file on our older robot it does not approximate anything at all. Surface milling is as it should be.

    need to see the code

    1) read pinned topic: READ FIRST...

    2) if you have an issue with robot, post question in the correct forum section... do NOT contact me directly

    3) read 1 and 2

  • backlash causing 50mm radius on a path?

    OK, that's a bit too much, but the infos he gives are a bit vague, so may be 50mm also are a bit vague.

    But many years ago we had a real big path error on a brand new robot, we could see it just by looking to the robot tool while he moved in free air. That was not far from 50 mm (nobody measured it), it was KRC1 with bad gear in axis 1.

    I agree: without the code and a description where the issue appears, it will be impossible to have a clue.

  • ok. Seems I am confusing people. CNC using CAD CAM program PowerMill.

    My issue is.

    One robot follows CDIS parameters set in tool path generation and the new robot doesn't. It puts random CDIS moves in that are much bigger.

    In pic attached you can see we limit $VEL and $ACC for all Axis to give us smooth Jerk free robot movement when machining.

    $APO.CDIS is set to 1mm

    $ADVANCE is set to 3 points.

  • Can you check the value of $APO when the actual error happens under Display > Variable > Single. Also it would be interesting not to see your program header but also the actual faulty program code segment. Maybe posting the two KRCdiags you took earlier might also be helpful with a short description in which program at what program line of code the error happens.


    So far all information we have does not allow any conclusions and we probably talked a lot about stuff that does not relate to the faulty behavior.

  • try to monitor you apo during the program run. im guessing the this might change after running home sub prg and tool change sub prg. if thats the case then try to change the location of you apo after the tool change.

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