Hibner: Software Testing Via Simulation

[ajlapp]

Thanks for the answers!

We typically use potentiometers for feedback. Any modeling recommendations for a potentiometer? It seems fairly straightforward to me.

Can you test for equivalent motor command? I.e. I could put the actual robot arm into a know position, say parallel with the ground.....then apply a known PWM to it's motor until it is held in place and not falling. Would this value then be equal to the equivalent motor command to simulate gravity??

[Chris Hibner]

Originally Posted by ajlapp

We typically use potentiometers for feedback. Any modeling recommendations for a potentiometer? It seems fairly straightforward to me.

I don't do anything to model potentiometers - I just use the angle calculated by the simple model as my sensor feedback. I do usually use a noise model (if you have your cRIO handy, use the noise testing method in my last post. If not, 2 degrees of noise is a good starting point).

Can you test for equivalent motor command? I.e. I could put the actual robot arm into a know position, say parallel with the ground.....then apply a known PWM to it's motor until it is held in place and not falling. Would this value then be equal to the equivalent motor command to simulate gravity??

If your arm is already built, that is exactly how we do it. You only need to do the test in one position, and the rest is proportional to the sine of the angle from vertical. If you do the test with the arm horizontal, then the equivalent motor command is EquivAtHoriz * sin(angleFromVertical). If you look at the arm model example, this is exactly what was done.

If you don't have the arm already build, you can do some rough calculations to get a good starting point. If you don't feel like rough calculations, using 0.2 seems to work pretty well for getting your software debugged.