Escaping from tight space

  • Hello,


    I am new in robot programming (I'm PLC programmer). I have a few questions on you. :help:


    1)
    My gripper enters to tight space in measuring station where clamps a part.
    Sometimes can happen that gripper can't clamp the part (GripperSpot-Tech error with stop program). Then operator should stop automatic cycle and EXT mode for restart program. I am pretty sure, if SAK movement to HOME starts from this area then gripper damage the measuring station.
    What is your idea for solution to avoid a mistake by machine operator?


    2) During robot movement to measuring station I would like to send to master controller (PLC) signal "ROBOT TOOL IS INSIDE THE AREA". This signal should block the measuring station movements. When robot tool leave the dangerous area signal should reset for enable the measuring station.
    What is your ideas for realizing?



    Thank you very much for your suggestion.


    Jan H.

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  • [size=2]welllll...... aborting program is a VERY brute way of "recovery" and all useful info is lost (motion trace, current tool, base etc.).
    i ALWAYS prefer to have program itself do retry or recovery - gracefully, for example by giving operator simple choice (button Retry, or dialog).
    [/size]
    [size=2]doing smart recovery after program is deselected is harder and requires much more effort. (see previous forum discussions)[/size]


    [size=2]check System Integrator manual and workspaces[/size]

    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

    Edited once, last by panic mode ().

  • Having operators stop the automatic cycle is definitely not ideal. When a robot fails to clamp a part, it should have a predetermined safe path to return home.


    A good idea is it to have a variable (example: INT robot_position) that tracks where the robot is. Once the robot fails to pick a part, it can back-track through the locations and return home safely.


    Say your robot has to got through 5 points to enter the clamping area. You can place a TRIGGER WHEN DISTANCE that increases the robot_position variable every time it successfully reaches a position. If it fails, you can create a switch case that steps the robot_back to position 1.


    Example:


    Here, the robot can receive a signal from the PLC that calls the homing subprogram, and the robot will return home through points you've already determined as safe.


    You can also create Workspaces, that track the position of the robot. Once the robot enters a workspace, the PLC can stop all movement of parts. This creates a safe area for the robot!


    Hope that helps!

  • Thank you for quick reply. I agree that continue in program is better way then program restart.


    I have a few issues:


    1) I studied workspaces. But I am still confused, because I don't understand in which tool or base is the workspace related?
    I have two grippers on flange. Is it position TCP in World? Or flange in World?


    2) I am using Gripper Spotech. When happens error during clamping/unclamping (timeout for input), declared output is set. But how/when the output is reset?
    According your advise I change strategy for clamping error for selecting RETRY, STOP, IGNORE. Is possible remove possibility IGNORE? Generally, I think it is dangerous.

  • Are you sure you are in the right forum? Do you have Kuka robot?
    If so please read pinned topic READ FIRST and post some details (KSS version, controller type, etc.)



    Then we can offer help by providing answers that are specific to your situation.
    For example Cartesian workspaces are using one or more points depending on KSS.

    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

  • Hey Jan,


    Generally, you should make sure the robot never ends a process outside of HOME. If the process was successful, failed, retried, etc., always return home and reset everything. That way your robot won't get stuck.


    1. Workspaces are flange (null tool) with respect to World. Check the manuals, it should clarify in more depth.


    2. In the example code I provided, once you've returned to home, simply reset all outputs (once you've reached case 1). The manual for Gripper SpotTech should give you more information on the different cases.

  • Yes, I am sure.
    I have KUKA Robot. KRC 4 controller with KSS version 8.5.6.


    Important question were about cartesian workspaces. From Instructions for programmers is not clear how to define tool and base for workspaces. I have two grippers in flange (see attached picture). I would like to define worspace for monitoring presence of both grippers.


    My another question is your recomended procedure for defining tool - TCP. How is possible define TCP of these grippers?



  • Thank you for feedback veronicav,


    I'll check it again.


  • Important question were about cartesian workspaces. From Instructions for programmers is not clear how to define tool and base for workspaces. I have two grippers in flange (see attached picture). I would like to define worspace for monitoring presence of both grippers.


    My another question is your recomended procedure for defining tool - TCP. How is possible define TCP of these grippers?


    Jan,


    You can create spheres around the important gripper areas. These spheres are in cartesian coordinates with respect to the null tool, so you'll have to do some measuring to see where they best protect your gripper. You can program the workspace to throw a warning or fault out when these spheres invade the workspace. Check the manuals, this should help get you started on the whole process.

  • standard Cartesian workspaces are always relative to WORLD, not a base.
    but the TCP used to be the only point checked.



    Then KSS8.3 started checking both TCP and center of the flange



    KSS8.5 still checks at least those two but allows more flexible configuration.



    All of this is in Programming Manual for System Integrators. In case of KSS8.5.x that is around page 182 ("6.14 Configuring Workspaces").



    Note that standard (not safety rated) spaces do not have spheres to place around tool. This is part of SafeOperation option.

    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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