Programming accurate location

    Hi all,

    I'm currently programming lot's of automatic toolchanges and drop off of end-effector onto zero-points.

    Given how tight both of these can be, it's taking a while to get the program positions as desired to allow smooth motion and I would ideally like to find a quicker method.

    The current methods I'm using are

    1) to feel the vibration on the end-effector during the locating of the toolchanger or zero-points.

    2) to watch the deflection

    3) using feeler gauges to find the gaps between the robot and tool-side toolchangers.

    I can then touch-up positions, rewind the program to reset the joints then play the program through again.

    Looking for any tips or best practices on this challenge.

    Thanks

  • 95devils October 2, 2024 at 6:14 PM

    Approved the thread.

    I usually create a TCP on one of the tool-changer locator pins, and on one of the contact points between the tool and the stand. Then move that TCP into optimum location in XYZ, then start rotating to bring the other pins/contact points into alignment.

    Putting a light behind two surfaces you're trying to bring together evently can be surprisingly accurate -- looking at how the light comes through the gap gives a quite good idea of how the two surfaces line up. Usually have to hit it from two different axes, though.

    It helps, but there's no really great way -- the process is definitely always finicky. Building your tool-change stands with a degree of compliance is definitely a good idea.

    Thanks for the tips! Going to give them a shot to see how it goes.

    Quote from Nation

    A real redneck way to do it is to get the robot close to the pins, hit all the break releases, then touch up the point once the robot has settled in.

    Don't think I'm brave enough to release all the brakes! 😅 Would there not be quite a bit of movement in each link when this is done?

    Quote from Kryten

    Don't think I'm brave enough to release all the brakes! 😅 Would there not be quite a bit of movement in each link when this is done?

    Its something you would do with the arm as close as possible to the pick/place position.

    I don't recommend doing it, but it is an option provided your tool changer stand can take the weight of the arm on it.

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    The methods you state are very effective. Yes they take time, but if the tolerances are tight, then time it will take.

    SkyeFire brings up a really good point, compliance in the tooling or stand can really help in these situations.

    Perhaps a little less redneck, you can check if your robot has a "soft servo" option. This allows the robot to be compliant in specified axes or joints. For example, Fanuc robots have a "soft float" option and can be used to push to robot into position or allow any mechanical tension to be relaxed into the actual position. Also, if you have a force option you could create a face matching program and press the tooling into the stand so that it face matches the tooling a specified force.

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