I programmed a large cell with multiple user frames and 3 of the user frames have critical teach points ( part loading into a loading station with next to no clearance). Minor crashes have happened here and there (miss-load) and every point will be fine except for my Packing finish part positions and i will have to reteach it. that particular program has 80 positions but only using one PR and offsetting it.
The cell has been running fine for months but whenever something happens like this i don't want the customer to have to reach that position every time. Can anyone explain why this is? is it because i am offsetting that one position so many times that any little bump on the robot will throw that position off? should i split it in half so one PR is offset for 40 positions and the second PR is offset for the remaining 40? is it something with the encoder?
Robot Crash
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Kyle0588 -
November 1, 2017 at 9:39 PM -
Thread is marked as Resolved.
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Hi
Explain to me
1) Do you load and reload 80 times the same PR ? In other words , your prog looks likel pr17 one time
pr17,2=pr17,2+2
pr17,3=pr17,3+5
l pr17 two times
plus another 79 times OR2)
l move
l move
l move
77 times then
PRBefore answering I want to have this clear
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I attached a picture of my programs. The left is my calculation program and on the right is my pack out program which it calls.
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Hi
The program looks fine. One approach, on departure, offsetting 38.1 mm. I don't see where it could fail .
What is your worry ? Teaching PR73 ?Also, I don't understand the pallet shape. what you show there is placing an object after another diagonally, but, that is unrelated to your question
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I agree with Fabian, your program is fine. If your position is off, then the crash is causing something to physically move or deform.
You can do several things.
1. Make things more mechanically robust
2. Try to prevent crashes - use a better approach offset, use sensors or compliant grippers
3. Have an automatic TCP calibration - Leoni is one company that sells a device to do thisSent from my SM-G930V using Tapatalk
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Thank for the reply's . The shape of the pallet is square. Its just odd to me after a minor crash that everything else in the cell (my other points) is fine except for my pack out. I thought too that maybe something physical was moving but i checked the EOAT and everything was still tight. I think i am going to split the pallet into two so that the PR taught to offset isn't such a critical teach point. I say its critical because i have taught the first position and looked great and will pack out parts for the first 6 rows but the last two rows i can see they start hitting the sides, so then i reteach the first position and move it slightly where you can barely see it move then the whole pallet is fine.
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Your pack-out position is relying on robot accuracy not repeatability. You have less margin of error than with a fixed point. This may be the reason that it is more "critical".
You have one point that must be a happy medium for all points on the pallet. Splitting it in two will theoretically half that accuracy error.
I understand what you are saying now and agree that this should help. Another method would be to add/subtract from the offset slightly after it goes beyond a certain distance. A compensation offset. It will have the same effect as having 2 points but will only require 1.