How does one configure the Inertia and Friction parameters in ST MC Workbench

[Martin1]

Posted on May 14, 2018 at 16:13

Hi,

When not using the motor profiler and instead writing all details by hand into the Motor Control Workbench (with Hall Sensors, Manual editing of PI variables disabled) at Motor - Parameters, there are fields for Inertia and Friction. So far, so good. Just the units are a bit confusing:

Inertia: uN*m*s2

Friction: uN*m*s

I thought that inertia had the units kg*m² and friction N*m, which I wasn't able to match with the given units.

Any clues how to do this right? Also does u stand for micro in this case or for something else?

Thanks,

Martin

[M. Palano · Accepted solution]

Posted on May 15, 2018 at 16:30

Hello Mr. Martin,

Yes sure, you are right, in that form the units are a bit confusing. Thank you for reporting this problem, we will try to improve them.

About 'u', yes, it

stands for micro (1E-6)

and

`N` stands for Newton the

SI

unit of Force(

1 Newton is equal to 1 kg

·

m

·

s-2)

https://wikimedia.org/api/rest_v1/media/math/render/svg/07948745d4db778de832933915f84be8bd9b4ded

So: N·m·s² = kg·m²

Hope this can help.

Best Regards.

[Martin1]

Posted on May 16, 2018 at 08:27

Nice, Palano. That works perfectly for the Inertia.

Can you also explain how to make sense of N*m*s instead of N*m? Or explain what kind of friction is meant here if not frictional torque?

Many thanks!

[M. Palano]

Posted on May 17, 2018 at 14:43

Hello Mr. Martin,

As you correctly said, the unit of measurement of the Friction Torque is [N·m]

The item required in the form of our tool, measured in [N·m·s], is the coefficient of the Friction Torque.

Friction

Torque

[N·m] : 

TF=  Î²Â·�?‰

where �?‰

is the angular velocity (Rad/s) and Î²is the coefficient required by MC-Workbench [N·m·s].

If not directly available, the the ST-MotorProfiler could be an effective way to detect it; in alternative, use external equipment like torque meter and speed meter.

With Best Regards.

[Laurent Ca...]

The question has been moved from the "Motor Control Hardware" section to the "STM32 Motor Control" section (the question is about the STM32 MC SDK). 

Best regards