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 Kuka LBR IIWA joint limits exceeded

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June 23, 2015, 09:52:13 AM
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HououinKyouma


Hi,

I was jogging the robot and somehow it got past its joint limits (as in overshooting, it's not just against the joint limit but it went over it). The problem is that I can't move it back to normal again because the robot blocks itself since it violated the joint limits. How can I solve this? The weird thing is that I am able to move the robot even more away from the joint limit in the other (wrong) direction. Please let me know if you have a solution for this, thanks.

Edit: I tried adjusting the software limits in $machine.dat and even tried setting the joint axis in question to be a continuous joint (no limits). Both didn't work..

Best,
Wilson

P.S. I attached a picture to illustrate my problem. As you can see, the joint limit for the first axis is supposed to be -170 degrees, while the current position is -192.62. Like I said, it is possible to turn the robot more into the negative side, but not back within -170 and 170 degrees.
« Last Edit: June 24, 2015, 01:48:46 AM by HououinKyouma »

Today at 08:19:47 AM
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June 23, 2015, 08:18:57 PM
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MECHI


I think you need to master the Axis of the robot which went out of its limit..

You can master the joint axis by:

Robot -> LBR_iiwa -> Mastering -> (select Axis, Unmaster then Master )

June 24, 2015, 12:27:15 AM
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HououinKyouma


Hi,

Yes, I already tried that. The system seems to be in a deadlock now: in order to move the joints back they should be within their joint limits. However, the joints are blocked because they're past the limits.. In order to master, the joints need to be within the limits as well. Right now if I try mastering it complains about the limit violation.

Edit: By the way all joints are currently unmastered, which also makes it impossible to run any application. Not that the application would work because of the limit violation though..
Edit2: It seems like my problem is similar if not the same as described here, only for a Kuka robot instead of Fanuc: http://www.robot-forum.com/robotforum/fanuc-robot-forum/jog-001-overtravel-violation/msg65228/#msg65228. Is this solvable using Kuka?
« Last Edit: June 24, 2015, 01:12:05 AM by HououinKyouma »

July 20, 2017, 09:25:21 PM
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LBRiiwaa


Hi HououinKyouma,

I have same problem with LBR iiwa . Did you get any solution for that problem ?

thanks

July 21, 2017, 02:40:01 AM
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HououinKyouma


Hi LBRiiwaa,

In the end I could not solve it myself, so I called Kuka and they solved it for me. At least back then, they claimed that it was not possible for us to resolve this issue ourselves, so they sent an engineer to fix it. I would suggest you to contact your Kuka vendor or contact Kuka directly, hopefully they can help you with it. Good luck!

July 21, 2017, 05:33:11 AM
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LBRiiwaa


Thank you HououinKyouma

Can you share please, what was the solution way of the Engineer, that Kuka send you for that Problem ? and any advice maybe ?
so that I can maybe apply that on my LBR


July 21, 2017, 10:24:10 AM
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HououinKyouma


I don't know exactly how he did it technically, but basically he set the joint position the robot was in to be zero, so he cpuld move it back to its original zero. However, he did that using a special program from his laptop which only Kuka has. So it should not be possible for us to fix it.

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July 21, 2017, 11:29:56 AM
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LBRiiwaa


 
yes you re right. Our problem is solved also today by an Kuka-Engineeer. and I ask to have the Program.
But customers can not  have that special Software.

Normaly it is okey LBR automatisch Mastern. But if you realy dont need that, I dont recommend to make Mastern/Unmastern.

thanks

December 23, 2018, 04:33:39 PM
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Mike Counsell


Hay all,

The same thing just happened to one of our iiwas also.  The pose was somewhat singular..... the move was v slow but J5 spun up prob too fast for it's own good and went to 170.77deg ...... .   I'm in the same position as the folks on this thread describe... no way to move/jog the arm....... guess I have to chase Kuka support .   

If anyone has any hints/tips on avoiding this I'm all ears.

Mike
UK ROBOTICS

December 23, 2018, 06:35:55 PM
Reply #9
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NullReference


Does entering KRF mode activate the motion enable?


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