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I have been meaning to ask this for a little while now, but whenever I check the position of the gripper when it is fully closed it never comes back as 255. It normally comes back around the 230 range, why is that?

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  • Etienne_SamsonEtienne_Samson Posts: 345 Handy
    @abeachy_HG24 because of the encompassing motion, when you close in parallel you close around 225 to 235, try having the fingers go encompassing you will see them move closer to 255.
    Etienne Samson
    Technical Support Manager - Responsable soutien technique
    +01 418-380-2788 ext. 207
    esamson@robotiq.com
  • abeachy_HG24abeachy_HG24 Posts: 78 Handy
    @Etienne_samson okay I think that makes sense. Is that spelled out anywhere in the manual? Everything I have found says that fully closed is 255 and fully up is 0.
  • Etienne_SamsonEtienne_Samson Posts: 345 Handy
    @abeachy_HG24 It's not very well detailed in the manual because it depends on your fingertips and how you actually pick the part. But yest, at 0 the finger bars are on their mechanical stop and at 255 they are closed on the fingertips. If you do parallel pick it's quite simple to predict part size vs opening, otherwise it can be complicated.

    You need to know a few things to predict the opening, first 0 and 255 are the maximum allowed position (mechanical stop). When you ask the Gripper to open you will notice it does not go to 0, it will go to something like 2 or 3 to avoid touching the stops (and thus preventing wear). Then you need to know your fully close, it will depend on your fingertip and grip force. If you have steel pads you can assume it will always close at the same position, something like 232 in parallel. Thus if you have 3 to 232 of range, you will know you have (232-3) encoder count for a 85 (or 140) mm opening. In that example you would have 229 count for 85 mm which gives you 0.37 mm per count, so asking the gripper to move to position 100 should close it by 37 mm. If you experience with that you will realize that you need to consider backlash and etc. but it can be useful to approximate closing position when you need partial motion.
    Etienne Samson
    Technical Support Manager - Responsable soutien technique
    +01 418-380-2788 ext. 207
    esamson@robotiq.com
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