Slew Rate Question

Simucube 2 Simucube 2 Questions
1

Hello!

I was wondering about some of the aspects of slew rate.

How is it measured? With or without any wheel? Does the motor power have any relation to the slew rate or is it a somewhat disconnected variable? If you leave the slew rate off (meaning it will go as fast as it can), then does changing the overall strength affect the slew rate? In other words, does it stay the same at say 10 and 25 nm?

Thanks!

2

Torque slew rate is a measure on how fast the system is able to change the torque. Whether there is a wheel or not, is not relevant since the torque is not dependent on what there is on the motor shaft. Changing overall strength does not affect the system’s maximum torque slew rate, however if the torque is scaled down the torque requests from the sim are also tuned down and the steepness of the changes are affected.

3

Hello! Thank you so much for the reply. Mind if I ask some follow up questions?

  • “Torque slew rate is a measure on how fast the system is able to change the torque.” - not entirely sure I understand. Do you mean the speed of the direction change?

  • " if the torque is scaled down the torque requests from the sim are also tuned down and the steepness of the changes are affected." - so I understood from that that if you tone it down in the sim, the slew rate is changed, but what about if you change it in the tuner and leave it at a 100% in the sim? Does that affect the slew rate the same way?

4

Well, if torque is to the left and then starts reducing and eventually goes to right, then that would change torque direction. But torque slew rate is the change rate of the torque generated to the motor shaft. It is limited by the motor drive electronics, motor tuning, and motor drive settings.

Yes. Eventually both will have the same torque request to the servo drive at the same time step, so the slew rate to achieve those targets is the same.

May I ask why you are asking these rather technical questions? They do not really mean anything with regards to FFB feeling or FFB processing as such.

5

I have a few Simucube bases and I’m just interested in how it all works, just for my own education :slight_smile:

May I ask if you know the base test app rfr wheel test? Is the data it gives reliable? Can you roghly estimate the slew rate from the data it gives?

Thank you so much again for your replies!