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Feedforward torque
https://forum.codesys.com/viewtopic.php?f=6&t=8697
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Author:  Josep M. Rams [ Wed Mar 14, 2018 9:34 am ]
Post subject:  Feedforward torque

Dears.

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!

Author:  alwoso [ Thu Jun 28, 2018 12:29 pm ]
Post subject:  Re: Feedforward torque

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!

Alfred

Author:  Josep M. Rams [ Thu Jun 28, 2018 8:58 pm ]
Post subject:  Re: Feedforward torque

Hi.

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.

Thanks

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Author:  alwoso [ Fri Jun 29, 2018 9:43 am ]
Post subject:  Re: Feedforward torque

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

Alfred

Author:  Josep M. Rams [ Sat Jun 30, 2018 9:31 am ]
Post subject:  Re: Feedforward torque

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....

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