Position accurate KUKA on linear track

  • Hello. I'm using KRC2 KSS v5.5.15 position accurate robot for milling. I put the robot on a linear track KL1500, because I have big work piece to mill (2,9m x 2,8m).PID file on the robot is only for the robot and not also for the linear track. If robot and linear track are mathematically coupled then I get error "3085 Dynamic model does not support this robRoot kinematic" and then I have no use of PID file and position accurate robot.

    If I set up the external kinematics parameters for linear track (#ERSYS to #NONE,....) to zero, then I have again the position accurate robot but not coupled. With this setup I can also move the robot on a track where I need it,but mill speed won't be accurate if I move the robot on track while milling.

    In order to mill such long work pieces I will have to move robot on linear track while milling, but robot and track aren't coupled then. I also have idea to move robot on track to one spot(E1 standing still), mill the work piece as much as I can from that standstill E1 spot, then move to other E1 standill spot and mill what was left, and so on.

    I would really like to have benefits from the position accurate robot, but then I have to break the milling process(cannot do it in one run), then I could have transitions misalignment because of this.
    I have to mill the part +-1mm accurate.

    Or do I couple the robot and track(by doing this I will disable the position accurate robot) and mill the part in one run(no transitions misalignment can occur)?

    What do you suggest what would be the best approach to use to get the best results and stay +-1 mm accurate?

    Thank you for any suggestions

    Edited once, last by DannyDJ ().

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  • I was faced with a similar problem recently. Kuka Support Areas in Germany eventually were able to modify my PID to include a kinematically linked external axis in the positionally accurate model. The robot was new, had not been installed, and was purchased with a motor for external axis - so Kuka may not be as forthcoming for an older robot.

    Unless the machining feed rate is critical, or you need the track kinematically linked for safe operation or some other reason, I would use the track unlinked. Unless you got a PID that included the characteristics of your particular track, which would require laser calibration, the track would be treated as ideal by the positionally accurate model anyway. Which would have the same level of accuracy as a positionally accurate robot not linked to the track.

    I'd be inclined to avoid machining a full reach from one E1 position, then moving along and doing another full reach. Without knowing the nature of your application, I'd expect any inaccuracies with continuous E1 movement would be subtle and probably not noticeable. Taking discrete positions along E1 could leave you with steps between sections.

  • Hi,

    your problem probably is that in old releases you where only able to mount robots in certain positions on a KL. Hopefully remembering correctly only mounting angles of only +-90 deg where allowed (see $ERSYSROOT in $machine.dat). In newer releases this restriction was lifted. So upgrading to a V5.6 should solve your problem .


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