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dannyhefdannyhef Unconfirmed Posts: 3 Apprentice
Hello,

I'm wondering if it is possible the get the joint positions (x,y,z) and not just the angles.
Does anybody know how to get them?

Dan

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  • jelmsjelms Posts: 15 Apprentice
    I think what you are asking for is Cartesian coordinates for each joint. There is a way to get the TCP in xyz. I don't think there is a built in way to request them. Computing the forward kinematic transform for each intermediate joints position in base coordinates using the specific robot parameters. You can probably use pose_trans() if you need to compute it in a script.

    I am curious why you would need that. Care to share?
  • matthewd92matthewd92 Founding Pro, Tactile Sensor Beta Testers Posts: 1,070 Handy
    I know that the elbow position is available on the RTDE interface but I cannot find any other location where it would be available via script.  I would submit your use case as a feature request to UR.  They may be able to add that to the script manual in future releases if you have a compelling use case or may be able to help you calculcate it.
  • dannyhefdannyhef Unconfirmed Posts: 3 Apprentice
    Thanks guys for your anwsers. I will forward my use use case to UR and maybe I can figure something with the rtde interface or to calculate the positions via manual rotation matrices. I need the positions because I'm working right now on my master thesis and I'm implementing dynamic safety zones depending on the nearest position of any joint or TCP to a human.

    I'll keep you updated
  • dannyhefdannyhef Unconfirmed Posts: 3 Apprentice
    Hey Matthew, you are totally right. That's all what I need, I have the Base, I have the Elbow via RTDE and I have the TCP. So now I have to work with the RTDE interface. Thanks a lot for your help.
    I tried the control loop example of the rtde from UR but it tells me that a variable is already in use and I have no idea why. The problem was also stated on zacobria but with no solution. Any ideas?
  • matthewd92matthewd92 Founding Pro, Tactile Sensor Beta Testers Posts: 1,070 Handy
    Not sure, do you have any URCaps installed on the robot?  Try taking out the input map, just monitor the RTDE outputs. That is the example i used originally to build our first RTDE listener off of. We did not inject anything into the robot through RTDE so we only listened to what it was outputting. 
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