PTP move to get out of error situation

  • Hello all.


    I am using the following equipment:

    KUKA KRC4 with Profinet-Profisafe (KSS 8.6)

    KUKA KR6-900 Robot

    S7-1200 F PLC (Tia portal V15.1)


    I have started to write the scenarios where the robots stops because of an error (collision monitoring, emergency stop and so on...)


    I have a lot of positions where the robot might stop where the first move should be straight up on the Z coordinate in order that the parts don't get damaged. Is there a possibility to execute a PTP move from the current position straight up for 200 mm?



    So, a PTP move + actual position + 200 mm only on the Z coordinate



    Thanks, in advanced.


    Cheers


    Aleix

  • Hello.

    Thanks for the input. I might also do a PTP move for 5 mm and then a linear move for 195 mm. So that the move will be more ''linear''.


    Cheers

    Aleix

  • Hello all.


    I tried the PTP move that Fubini mentioned. It works if a previous PTP move was executed. But if a previous move was stopped because of an error the move does not work. The error was that the speed for A1 is not defined or something like it. Can't remember now(will post it on Monday). So, I programmed a straight up PTP move to get out of the danger zone so that I don't damage the part in the gripper or the griper/robot.


    The thing that bothers me is this.

    I run my main program in EXT mode. THE PLC starts the robot, starts the program and the Robot program runs. But if an error occurs (in my case the robot detects a collision because, some time a part is slightly damaged and it doesn't fit in the test nest where the robot wants to place it). The robot program stops.


    So, I try to acknowledge and reset the collision alarm with the $conf_mess. But I just get another waring message instead... Can't remember what it is. I will post it on Monday.


    Are there any limits to what this, $conf_mess confirms...?


    Cheers

    Aleix

  • Hello all.


    Thanks for the input so far. I've managed to write the exit procedures with your help, but still I can't acknowledge the collision errors that happen sometimes.

    Is it possible to acknowledge a collision error while in EXT mode with the PLC?


    If I try to acknowledge it I get an additional warning...

    Are there any limitations as to what can be confirmed with the PLC ?


    Thanks, Cheers

    Aleix

  • If I try to acknowledge it I get an additional warning...

    Are there any limitations as to what can be confirmed with the PLC ?

    That additional warning is "Active Mode Required," yes?


    Yes. I don't have a comprehensive list, but collision errors generally can not be reset remotely. There are some others. The underlying reasoning is that certain errors should require someone to physically come to the robot and resolve the root cause of the error "hands on."

  • Hello.

    Not all parts are ok, so they get caught on the nest and the robot gives me the collision error.

    Can't do it any differently unfortunatley.

    Can you change the tooling, so it could react instead of the robot? Maybe it could have some elasticity and sensors to detect collision? Trying to automatically acknowledge robot collisions is a bad idea.

  • Hello.

    Not all parts are ok, so they get caught on the nest and the robot gives me the collision error.

    Can't do it any differently unfortunatley.

    ofcourse you can do it differently.

    You can monitor the torque and if it get to certain limit abort the move, with interrupt.

    That way you can prevent the robot from collision it self and further damage.

  • ofcourse you can do it differently.

    You can monitor the torque and if it get to certain limit abort the move, with interrupt.

    That way you can prevent the robot from collision it self and further damage.

    Hello.

    Yes haven't thought of it this way...

    So my montion where most of the collisions are hapening is on the Z axis, so If I monitor torque on Axis 3 to 6 this sould let me detect the collision beforehand...


    Can you please help me out how to do torque monitorning? How are the torque variables declared, do I write the monitoring in SPS??...

  • read pinned topic READ FIRST, it contains references to key manuals

    check those manuals for mention of torque (Programming manual for system integrator, System variable manual)

    optionally setup display overview to easily see the values during operation

    use same Programming manual to learn more about interrupts.

    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

  • another option is to limit the current during certain moves so arm is "soft"

    Hello, Could please you give me some more information please how to achieve this?


    By soft you mean that it allows for wiggle room? How does this affect the accuracy of positioning?


    Cheers

    Aleix

  • Hello, Could please you give me some more information please how to achieve this?


    By soft you mean that it allows for wiggle room? How does this affect the accuracy of positioning?

    Look up $TORQUE_AXIS. This is useful, but has definite limits -- for one thing, it should not be used on A2 or A3, because it's liable to make them "sag" under gravity effects. And its use on A4-A6 is highly situational.

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