Simple method for controlling CIM speed?

[penguinfrk]

For our senior float, we're trying to make an inflatable Harry Potter doll revolve around a paper mache snitch.

A really quick model of it can be found here: http://www.youtube.com/watch?v=MFJ9R2tNFrQ. I apologize for the low quality video.


To power it, we have two CIM motors on a Toughbox Mini sharing one output shaft. There's an idler wheel for support.

Is there a good, simple way to regulate the speed of the motor? We need to slow it down further than the gear reductions due to safety issues with our administration. It doesn't have to be a mechanical solution.

We're thinking of using jaguars right now, but none of my team's seniors are on programming, so we're pretty in the dark about how to do it. We don't need it to be remote controlled; the system can be powered as soon as the breaker is flipped. Which electrical components will we need (are the cRIO, sidecar, power distribution board, etc. all necessary)? What programming would be necessary?

Thanks for the help!

[Jeremy Germita]

I have a no-programming-involved solution....
You could use a jaguar, or any motor controller with a PWM input. And build the servo controller circuit below.
The Jaguar and Victor can take in any standard servo signal input, they just need to be calibrated. Since you are not using the full range, this may not be necessary...

Since you are using 2 motors, I recommend you use a PWM Y cable to split the signal to the two controllers.


image credit 555-timer-circuits.com

This solution will keep costs low and let you keep the PDB, cRIO, and other elements.

The only modification to the circuit is that you need a 5 volt regulator for the circuit. you can connect this directly to your power supply and it will start moving at the set speed as soon as you power on.

Please! I cant stress enough the importance of safety. Test this without any load on the shaft first, then when you have your desired speed, fix the load onto it.

If you have any questions about this, ask away.

Jeremy G.

[Ninja_Bait]

Or you could just use a weaker battery than the 12v FRC monsters.

[JamesCH95]

Or even a 6V battery.

[Ether]

Originally Posted by JamesCH95

Or even a 6V battery.

Wire the two CIMs in series and connect them to a 12volt auto battery.

[nighterfighter]

You could also use an Arduino's PWM output feature to control either a Victor or Jaguar, so you can control its speed more accurately. That also elminates the need to use the cRIO. Unless of course you need it for something else.

[MrForbes]

buy a servo tester.

http://www3.towerhobbies.com/cgi-bin...ster&search=Go

[Chris is me]

A Victor and a Vex controller.

[JamesCH95]

Originally Posted by Ether

Wire the two CIMs in series and connect them to a 12volt auto battery.

Simplicity at its best. There is no need for fancy and expensive controllers.

[MrForbes]

An advantage of using a speed controller is that you can set the speed nice and slow for the safety demo, then speed it up for "real life"