Measuring SimScape friction torque

What would be the best way to measure friction torque generated by the rotational friction block shown in the image of a simple rotational system in the image? The system has a constant input connected to an ideal torque source and an idealised rotational motion sensor as the output.

Answer 1

[Juan Sagarduy]

Hi Vivek I think that a torque sensor between the inertia and the friction element would work great. Br Juan

[Vivek]

Hi Juan I have attached a snapshot of the connection:

The parameters are set as follows:

The output looks like this:

It appears that the friction torque starts from -468.66Nm without displaying the characteristic starting curve.

• What could be the issue here?

On the other hand, if the Rotiational Simscape Interface block is used, the friction torque reads -156.2Nm (constant value, ratio:-0.33).

• Why could this be different? (If this is an acceptable solution)

Thanks in advance for your help!

[Juan Sagarduy]

Hi Vivek,

This is the way to capture the friction torque. The sensor has to be in series (not parallel) with the friction element. The results show the expected behaviour.

Br Juan