Definition of arm loads

EricH

How do I know where the arm frames are? Is it written in some specification document?

I want to define an arm load, that is mounted on J4. I know the mass and mass centre coordinates from a specific load frame. Now I want to bring the mass center coordinates into coordinates of the J4 arm frame, but therefore I need to know where the arm frame is.

Thanks for the help!

lemster68

System parameter manual, 6.2.6.  J4 is Fanuc talk, could get you beat up in an ABB forum. 

EricH

So what is a better term for J4? I better don't mess around with you guys

That manual has the same content like system parameters in the help documentation inside robotstudio. It only describes how to enter arm loads, but not how I get the position of an arm frame, so I don't know whether the values I enter are correct.

Here in this picture you can see the frame for arm 3. I know where the mass center of the load towards a special reference is, but I don't know where it is in arm 3 frame.

lemster68

Answer to your first question:  I have always referred to axes as axis 1, axis 2 and so on.  Just like on the pendant, you see 1,2,3 or 4,5,6.  Second, Take the robot to sync position and measure from the center of axis 3 (where it pivots).  Units will be meters.

PetrB

Is the arm load mass center point defined in meters? It only allows +-30 and manual doesn't says anything about units.

lemster68

Yes, it is in meters, for example, 100mm = 0.1.

lemster68

Also, good to see that you are trying to set things up correctly, so many fail to do the armloads.  The next step, very important and sometimes missed, is to go to "ARM" and set "Use Arm Load" to the Arm Load that you have set up.  I think that many think that if they do arm load 3, the robot associates it with axis 3 automatically.  Such is not the case, you can tell it to use any load for axis 3, including any additional ones that you may define (add) in the MOC.cfg.

PetrB

Thanks for that, I really missed that step.

lemster68

You are welcome.  Unfortunately now, your Tooldata load and any loaddata will be somewhat inaccurate.  Since I suppose you have this correct now, I suggest to run your LoadID routine to get the best possible accuracy now.

PetrB

Correct, will have to run it again. I believe I've seen in manual, that you can not run load identify for arm loads, is that right?

lemster68

That is correct, it is only for EOAT and any payloads that they pick up, if applicable.