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make LIN slow near singularities during AUT

  • AiSard
  • June 27, 2018 at 1:25 PM
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  • AiSard
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    • June 27, 2018 at 1:25 PM
    • #1

    KR C4 KSS 8.3.25

    Is there a way to slow down LIN movements as the robot approaches singularities during AUT mode? (similar to how it is in T1 and jogging)

    I've tried setting $CP_VEL_TYPE to #VAR_ALL but not seen any effect (unless it only kicks in when the robot would otherwise BRAKE?)
    Or is there a way to set max axis velocity limits for LIN movements or something similar?

  • panic mode
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    • June 27, 2018 at 5:53 PM
    • #2

    change orientation control to Wrist PTP

    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

  • AiSard
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    • June 28, 2018 at 7:46 AM
    • #3

    From what I understand, isn't #JOINT to do with freeing up the orientation?..
    Which would be rather dangerous for my set-up....

    I am asking specifically for ways to limit/reduce the speed when getting close to the wrist singularities (with LIN movements during AUT)

    I feel like I've read in passing that this might be possible on the forum (granted may have misunderstood as it didn't go in to detail), but usually gets passed over as I guess the normal use-case (spray painting?) would suffer from variable speeds (whereas my use-case is unaffected)

  • panic mode
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    • June 28, 2018 at 12:14 PM
    • #4

    What exactly is your use case? What exact singularity is giving you a problem ?
    What is the robot pose in this case? Did you read system variable manual?
    Hint: don’t have to read it all, just search for term ‘singularity’.
    Not all motion types are afeected by singularity, did you consider to use different motion type near this point?

    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

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    SkyeFire
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    • June 28, 2018 at 3:25 PM
    • #5

    Without knowing more details of your setup and application, it's hard to provide concrete options -- for example, an A3 singularity isn't going to be fixable by simply adjusting speed.

    One possible approach might be to add code to the SPS loop that monitors the axis (axes?) that are approaching their over-speed limits due to the singularity, and adjusting $OV_PRO down proportionally.

  • arikrundquist
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    • June 28, 2018 at 10:06 PM
    • #6

    Look up $VEL_AXIS_ACT and/or $SINGUL_DIST in the System Variables manual, then use one or both to add logic to decrease the speed of the appropriate axis.

  • AiSard
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    • June 29, 2018 at 9:00 AM
    • #7

    A4-6 singularity. Not looking for other options. Specifically looking for speed reduction.
    Path and Orientation is Fixed. Only looking for ways to reduce speed.
    (sadly too late to change the tool orientation as usual :icon_frown: )
    Thought I had constrained the question properly, guess not :icon_confused:

    Ah. Main thrust is not for production, but for an audience. If that makes it easier to understand. [EDIT: Use-case is a paintbrush. ]
    Trying to specifically reduce the fast movement of the A5 here,
    while singularity avoidance is being handled by simulating the possibility space as much as possible (which is a separate thing to this)

    I guess no-one mentioning $CP_VEL_TYPE means I was going down the wrong path then I guess (also in the Systems Variable Manual).
    SPS to manually monitor the axis seems like the way forward... Except not quite confident enough to mess with the SPS for the first time in the time left..
    Might have to fall back on just reduced overall speed at this point and hope for the best :icon_confused:

    As for use-case, hopefully this truncated version is enough, not sure if still needed (wrote it before the above) but I spent an hour wracking my head on how to succinctly explain it so..:

    Quote

    Path can be treated as (effectively) random if constrained
    Orientations are curated to minimize singularities.
    But due to the randomized path and wide orientation possibilities, affected points are also unknowable ahead of time.
    Pose is fixed to maximize volume of working area (and orientations are curated according to pose)

    Other motion paths passed over as they leave orientation unconstrained in various ways

    Again, Path and Orientation are effectively Fixed.
    Speed is the only free variable to change.

    Edited once, last by AiSard (June 29, 2018 at 10:13 AM).

  • Fubini
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    • June 29, 2018 at 12:38 PM
    • #8

    No you are not wrong $CP_VEL_TYPE ist the singularity strategy slowing down the robot to maximal allowed axis velocities near singularities. But it is not guaranteed to work under all circumstances. Have you tried #VAR_ALL and #VAR_ALL_MODEL Settings in $CP_VEL_TYPE? If you are crossing the singularity the robots cartesian (linear) velocity will be zero "inside" the singularity and only the hand axis will move (flipping A4 and A6 180 degrees). Basically $CP_VEL_TYPE is responsible for being able to jog from standard home Position (A1 0, A2 -90, A3 90, A4 0, A5 0, A6 0)

    The hand axes move is necessary for the A5 status change when crossing A5 = 0, because continous path moves like LIN always keep status constant.

    Fubini

    Edited once, last by Fubini (June 29, 2018 at 12:45 PM).

  • AiSard
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    • June 29, 2018 at 1:30 PM
    • #9

    I only tried #VAR_ALL and tested it going near the singularity (not through it) (I gathered that #VAR_ALL_MODEL had a higher velocity cap than #VAR_ALL so didn't try it out)
    Not seeing it slow down, I became unsure if I understood the command correctly and so came to check in the forums before moving further
    I guess I just never hit the maximal axis velocity (not being quite close enough) so didn't see any effect hm

    Is it possible to set the max axis velocity that #VAR_ALL references? (or something to the same effect)
    This was my initial direction, thinking to cap the overall velocity near singularities.

    Edited once, last by AiSard (June 29, 2018 at 1:35 PM).

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