paper: Simple Motor Calculator

[bmlarson12]

WOW!!! How did you do this? I have been looking for a graph of the information so I could get the general values, but this is far better!

[Ether]

Originally Posted by bmlarson12

WOW!!! How did you do this? I have been looking for a graph of the information so I could get the general values, but this is far better!

If you assume that the speed vs torque and the current vs torque "curves" are straight lines (which is the standard assumption for almost all the motors used in FRC), then most of the equations are fairly straightforward to solve explicitly.

For example, at the rated voltage and for a given torque tau, you can find the speed as follows:

speed = free_speed*(1-tau/stall_tau)

some of the other calculations, for example solving for efficiency or finding voltage when given rpm and torque, are a bit trickier, but not too bad.

I'm glad you discovered it and hope you find it helpful.

[wireties]

Ether == Awesome - any chance you'll part with the source so I can compile a Linux version?

TIA

[Ether]

Originally Posted by wireties

Ether == Awesome - any chance you'll part with the source so I can compile a Linux version?

It would be good to have a Linux version.

I'll pull out the formulas and post them.

Give me a couple of days.

[wireties]

Originally Posted by Ether

It would be good to have a Linux version.

I'll pull out the formulas and post them.

Give me a couple of days.

If it was a windows console app, it will probably just compile and run quickly with minor changes. You can send the source if you want.

[Ether]

Originally Posted by Ether

It would be good to have a Linux version.

I'll pull out the formulas and post them.

Give me a couple of days.

Here ya go.

[wireties]

Originally Posted by Ether

Here ya go.

I'm a busy guy - no time soon to re-write the program, not with work for 3 customers in process and being in the middle of build season. I apologize if I was not clear. I was offering to take your source and re-compile to create a Linux executable. No disrespect intended but I don't need the formulas ;o). I'm an EE and have been designing opto-mechatronic embedded control systems for 30 years - I know the formulas.

Thanks anyways.

[Ether]

Originally Posted by wireties

No disrespect intended but I don't need the formulas ;o)

Of course. I thought you were after some of the more arcane calculations, like solving for operating range given operating volts and desired minimum efficiency*. I've never seen that published anywhere.

Anyway, unless you have an old copy of Kylix the source wouldn't serve the purpose intended.

Oh well, the equations are out there for anyone who might be interested.

*it's not as useful as other calculations, I know, but I included it because it's interesting to play around with and may provide some insight

[wireties]

Originally Posted by Ether

Anyway, unless you have an old copy of Kylix the source wouldn't serve the purpose intended.

Well, it just so happens that I do ... BTW, FIRST Team 1296 very much appreciates all the great advice you regularly disperse on CD!

[yash101]

THAT IS SWEET AND USEFUL