Re: paper: Simple Motor Calculator
 

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.

Re: paper: Simple Motor Calculator
 

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

TIA

Re: paper: Simple Motor Calculator
 

It would be good to have a Linux version.

I'll pull out the formulas and post them.

Give me a couple of days.

Re: paper: Simple Motor Calculator
 

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.

Re: paper: Simple Motor Calculator
 

Here ya go.

Re: paper: Simple Motor Calculator
 

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.

Re: paper: Simple Motor Calculator
 

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

Re: paper: Simple Motor Calculator
 

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

Re: paper: Simple Motor Calculator
 

There have been a number of occasions recently where I wanted to calculate a motor's applied voltage given rpm and amps. To make this more convenient I added another option to the motor calculator.

I have also changed the display to show waste heat watts instead of input watts, since that seems to be of somewhat more interest. Input watts is easily calculated by adding output watts and waste watts.

Re: paper: Simple Motor Calculator
 

New version just uploaded. Includes VEX MiniCIM and BAG motors.

Re: paper: Simple Motor Calculator
 

Motor Calculator has just been updated to include the now-legal Banebots M5-RS555-12 motor.

The new version (MCALC_2013b) is at the bottom of the list of attachments.

Re: paper: Simple Motor Calculator
 

Motor Calculator has just been updated to include all 2014 motors. Sorry for the delay. Better late than never :-)

http://www.chiefdelphi.com/media/papers/2432

Re: paper: Simple Motor Calculator
 

Motor Calculator has just been updated to include am-2161 & am-2194 motors (for am-0914, 2193, & 0915 gearmotors)

http://www.chiefdelphi.com/media/papers/2432

Re: paper: Simple Motor Calculator
 

Thanks again Ether!! You would not believe how much we use this utility.

Re: paper: Simple Motor Calculator
 

THAT IS SWEET AND USEFUL