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Speed - Torque controller questions

Forum 1
(@anonymous)
Active Member Registered

Hi, 

based on your controller, I want to know if in the speed mode is the motor current command: Imcmd = (ki/S+kp)*(speedcmd-speedmeasured)?

Where S is the Laplace operator.

In position mode. Is : SEEDcmd = (POSSITIONcmd-POSSITIONmeas)*ki

and

IMOTORcmd = kp*(SPEEDcmd-SPEECmeas)

Thanks

This topic was modified 3 months ago by Anonymous Anonymous
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Topic starter Posted : 17/06/2021 11:38 am
SOLO Team
(@milad)
Chief Member Moderator

Hi,

to answer your questions, I'll go as below:

1) In the speed mode is the motor current command: Imcmd = (ki/S+kp)*(speedcmd-speedmeasured)? Where S is the Laplace operator.

yes and No, yes for the reason that in theory, you're right, the output of the speed controller's PI is feeding the Reference of the current( torque) controller, and No for the fact that in a real world motor controller, everything happens in Digital form, so there is no Laplace domain, and all is happening in "Z" or a discrete domain, so if you take the continuous PI controller that you told me above, and convert it into discrete domain, then we can agree that the output of that digital controller is feeding the current controller in reality.

2) In position mode. Is : SEEDcmd = (POSSITIONcmd-POSSITIONmeas)*ki and IMOTORcmd = kp*(SPEEDcmd-SPEECmeas)
The position controller is exactly like the speed mode, so the output of the PI controller from the position will feed the reference of the speed controller, so again like the current controller the PI should be considered as a digital PI controller in "Z" or discrete domain.

If you look back to position controller from to current controller side you'll see two PI controller of Speed and Position back to back, and this forms a system of 2nd order which is not what you mentioned above I believe and it's more complicated than that. To get the idea of how the Torque, Speed, and Position controllers are coming back to back in SOLO you can have a look on this diagram and read more about them here.
I will remain available.

Regards
Milad

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Posted : 17/06/2021 11:45 am
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