Fanuc Payload & Inertia Setup

  • I know this topic has been discussed in other threads. However, I am still not 100% clear.

    I have attached an image showing my tooling setup including the calculations for Inertia ( I am using Creo in this case)

    Note: in my image the Robot TCP is the center of the orange circle plate (labeled x, y, z in the image).

    I want to make sure I am using the correct values for inertia as highlighted in the red boxes.

    I understand that I need to convert the units from mm^2 to cm^2. Also, I apparently need to divide everything by 980 to convert from kg to kgf.

    So my results would be:

    Ix: 0.909 kgf*cm^2

    Iy: 0.953 kgf*cm^2

    Iz: 0.084 kgf*cm^2

    What do you think? Does this look close?


  • You are using the correct moment of inertia axis, but your reference coordinate system is wrong.

    Z needs to be out of the faceplate interface, and X needs to be to the top dowel.

    Also, contact your Fanuc rep, and ask for the latest version of the payload checker excel sheet. You can input the numbers you got from creo into it, and it will tell you if the robot you selected is within payload or not.

    Judging by the size of your wrist bolt pattern, you would be fine.

    Check out the Fanuc position converter I wrote here! Now open source!

    Check out my example Fanuc Ethernet/IP Explicit Messaging program here!

  • I got you.

    You want to put in the primary values Ixx, Iyy, and Izz from the CAD export. I assumed the values are from the flange and not about the center of mass. Corrected: Values are about center of mass.

    Select kg and m for the units for CAD.

    Use this: 1 kg*m2 = 10.197 kgf*cm*s2

    If you need convincing, the conversion is as follows:

    First, know that 1kgf = m*g = kg * (9.81)m/s^2=9.81N

    Start with what Solidworks gives you: kg*m^2

    -Then, multiply by (s^2/s^2)

    kg*m^2*(s^2/s^2) = (kg*m/s^2)(m)(s^2)

    Note: 1 kg*m/s^2 = 1N

    Substituting, you have

    (kg*m/s^2)(m)(s^2) = (N)*m*s^2

    Next, you sub 1kgf = 9.81N

    (N)*m*s^2 *(1kgf/9.81N) = kgf*m*s^2/9.81

    Finally, convert m -> cm: 1m/100cm

    (kgf*m*s^2/9.81)(100cm/1m) = (100/9.81) kgf*cm*s^2

    =10.194 kgf*cm*s^2

    Edited once, last by JCOLE ().

  • Found his really useful... You can change to SI units By Changing the variable $SI_UNIT_ENB to TRUE.

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