Feedforward torque

  • josepmariarams

    josepmariarams - 2018-03-14


    I am working with an Lenze i700 it wors fine but I cannot give to the drive an torque addition.

    Torque addition is mapped in pdo, but it is allways 0, and I have not seen in anywhere the load inertia. Anybody knows how I can parameterize it?.

    In any case, it is possible to access the addtorque variable from the axis_ref?. If it is possible the torque feedforward could be cqlculated having in count load inertia and static and viscous friction.

    Be healty!

  • alwoso

    alwoso - 2018-06-28

    Hi Joseph!

    Are you still looking for a solution? Function block "SMC_SetTorque" of library SM3_Basic should do this job to fill the fSetTorque in the axis_Ref. I'm using it with CiA-402-drives (Stober SI6, SD6), and it works fine....

    Good luck!


  • josepmariarams

    josepmariarams - 2018-06-28


    In Lenze drives exist setTorque and addTorque.

    The first is when you are working in torque mode and the other acts as a feedforward when you work in sync velocity or position mode.

    I have not test, but I am thinking that it doesnt works.


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  • alwoso

    alwoso - 2018-06-29

    Hi Joseph!

    You are right, in the standard AXIS_REF_SM3 of Codesys there is no entry for a Torque Offset. What you can do is to map the parameter manually to a plc-variable and write the calculated torque offset to that variable (must be in units that the drive needs!).

    If Lenze has a special Softmotion driver (may be part of their control system), this might have an extended AXIS_REF, where the offset is mapped internally. But that's something I don't know....

    Or maybe, internal in the drive they interpret fSetTorque as an offset, if the drive is in mode csp or csv..... This should be written in the documentation....

    Best regards


  • josepmariarams

    josepmariarams - 2018-06-30

    Hi Alfred.

    The question is:

    In axis_ref, is not vissible an addspeed variable, but it is mapped to the addspeed pdo.

    I think there is an non vissible addtorque variable in the axis_ref struct.

    Yes, I can create an add torque variable in my code and mapping it, but...

    You can extend axis_ref, but twincat maps an axis_ref directly to the input outputs, not your extended axis_ref....

    Sent from my Moto G (5S) Plus using Tapatalk


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