Problem with the user frame switching

  • Hello,

    I'm working on the pick-drop application using M-710iC robot and R-30iB controller. Now I dicsovered interesting problem.

    I use two of user frames. One user frame is used for part picking and another is for part droping. If the user frames are switched during the movement, robot jerks. It looks like shock, probably the robot stops immediately in the middle of movement and starts again without ramps.

    Is it possible? Is it normal? How is the proper way to switch the user frames?

    Thank You for any suggestion.

  • I would guess that maybe you need to make the motion before you call the new frame a FINE motion.
    It could just be reading ahead too quickly-- but I don't have a Fanuc on hand to test for you.

    Let me know if this helps.

    Primary robot language: Fanuc.

    Expertise: iRVision, PalletTool, iRPickTool, DCS.

  • Strange. I have been doing this on many projects, and never faced such problem.
    Are the frames defined with the same configuration?
    Do they significantly differ by WPR angles?
    Is there a sharp corner in between the motions?
    Can this be a stop by false collision detection with following autorecovery?
    Do you use acceleration override?

  • Hello Sergei,

    thank You for Your interest. The frames are rotated around Z axis with angle which is close to 90degree. Also XY planes are in the different levels (difference is under 50cm).
    It is strange that the robot jerks in the middle of joint movement (but Im not sure if the points are defined by joints or in carthesian, i will look tomorow).
    I think that it is not caused by false collision detection, because robot did not display any alarm.
    I'm not using acceleration override.

  • its possible the change of frame is not the cause. if there is too much logic between one point and another the motion interpreter cannot determine a path. try teaching a dummy place point using the pick uframe. if this eliminates the hesitation then you are on the right track. i suspect however you are chasing the wrong problem. There are a couple of common culprits. a lot of call/macros between when the last path was generated and the new one is declared. any decisions that have to be made between the two, what pallet to go to for example, can keep the robot from calculating a smooth path. using the same PR's for dynamic offsets can sometimes cause problems as well. if possible remove and LOCK/UNLOCK PREG commands. the other one i have seen is excessive loops. anything that jumps up in the program. ie JMP LBL[10] or an ENDFOR can really slow the robot down. if that is the case you can can try to modify $PG_CFG.$jmpwait_upr. you can also look at $SCR.$maxpremtn. though that one has not generally produced as good of results for me as the name would suggest.

  • TomasM, can you make a test with the same motions between the same targets, but redefined in World coordinates.
    This would clarify whether switching the frames causes the problem.

    And by the way, is not the robot passing singularity when "jerking"?

  • Thanks to all.

    Today I made next few exeperiments. Result is, that robot jerks when I'm switching the tool frame and also when I'm switching the user frame. No mather if the movement is linear or joint. No mather if the points are defined as carthesian or in joints.

    But what is important, if I switch robot mode from manual to automat, every problems are away. Robot moves smothly in all speeds. That is the happy end for me.

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