Motors Per Motor Control

[V.M.Santore]

Does every motor have to have a dedicated motor control, such as a jaguar, or can multiple motors use one motor control?

[Mark McLeod]

Usually one motor per motor controller, especially for the larger motors.

See R52 for exceptions on the smaller motors (less than 100w max power).

[V.M.Santore]

Usually one motor per motor controller, especially for the larger motors.

See R52 for exceptions on the smaller motors (less than 100w max power).

Thanks!

[jmiller18]

At the LA regional in either 2010 or 2011, one team used two motors on one victor this caused it to flame for a few seconds. They were able to repair the robot and renamed it the phoenix. That should answer your question.

[Al Skierkiewicz]

No rules prior to 2013 allowed more than one motor per speed controller.
See Table 4-4 for a complete listing.

[tsaksa]

Usually one motor per motor controller, especially for the larger motors.

See R52 for exceptions on the smaller motors (less than 100w max power).

However, keep in mind that this does not mean you cannot connect multiple drives to the same PWM signals using a Y cable. On many types of drives this can be a very good idea to insure that the drives stay in sync, and do not fight each other.

[cgmv123]

On many types of drives this can be a very good idea to insure that the drives stay in sync, and do not fight each other.

Assuming the controllers react to inputs the same way. (Otherwise known as being calibrated properly.)

[apalrd]

For smaller motors, they will be just fine under a single control (and this is legal now, finally).

Example:
The combined stall current of 2x window motors on a Talon is well below the continuous current spec of the Talon and on a 40a breaker it will be impossible to trip (the PTC in the motors will trip first). We wired our 2011 practice robot using 1x Victor, using 2x Victors and a Y-cable on the competition bot.

Don't put two large motors like CIM's on a speed controller and expect it to live, though (although the 40a breaker *should* trip first).

Y-cables are also highly recommended whenever two motors do the same thing. Our 2012 robot in it's final state had 16 speed controllers (14x Victor 2x Vex) and 2 servos on a single digital module and sidecar, all made possible with Y-cables.

[Al Skierkiewicz]

Just to clear up some confusion...
The snap action breakers trip on over current but reset almost immediately. When really over stressed, they will actually buzz. Be careful, once the buzzing starts, the heat begins to rise. These little devices have been known to leave marks on the unwary.

[Cal578]

Usually one motor per motor controller, especially for the larger motors.

See R52 for exceptions on the smaller motors (less than 100w max power).

Where did you get this 100W limit? I don't see that in the manual. Note that (as Al said), Table 4-4 has an explicit list of what motors can share one controller. Not all motors under 100W (or even 50W) can share a controller. The biggest one, the BaneBots MS-RS775-12, is 83W, so the total would be 166W if you want to put two of those on a controller.

Personally, I would only put two matched motors on one controller, and preferably when they're driving one load (e.g. one shaft). So, two window motors might make sense on one controller.

[Al Skierkiewicz]

Gerry,
He wasn't quoting a rule, just grouping the motors by output power.

[Cal578]

Gerry,
He wasn't quoting a rule, just grouping the motors by output power.

I see. I'm not sure the snow blower motor is included in the motors allowed to share, and it's only 30W. I haven't looked at a snow blower motor closely, but judging from the picture, I think it's a worm drive, so it wouldn't count in the "am PG motor" group. I could be wrong (wouldn't be the first time).;)

[Al Skierkiewicz]

Gerry,
This question is currently on the Q&A

[Cal578]

Ok, I just looked at that Q&A (Q274 (https://frc-qa.usfirst.org/Question/274/r52-lists-motor-controllers-to-be-used-with-allowable-motors-i-do-not-clearly-see-a-listing-for-the-snow-blower-motor-fc13-067-am-2235-what-are-the-requirements-for-motors-controllers-for-this-motor), answer still pending as I write). It's interesting, but to me just academic. We're only allowed to use one snow blower motor, and I wouldn't put mismatched motors on one controller, so the answer won't make any difference to our team. If we use a snow blower motor at all, we'll treat it as a one-motor-per-controller device.

[Al Skierkiewicz]

If we use a snow blower motor at all, we'll treat it as a one-motor-per-controller device.
Since you can only have one snow blower motor on the robot, that would be an appropriate choice.

[kingbrandon14]

Last year, we tried to run 2 motors with 1 jaguar, but they wouldn't let us compete with it like that. So the answer is no :(

[Mark McLeod]

Last year, we tried to run 2 motors with 1 jaguar, but they wouldn't let us compete with it like that. So the answer is no :(
Those were last year's rules.
This year specific motors are called out by R52.

[apalrd]

Last year, we tried to run 2 motors with 1 jaguar, but they wouldn't let us compete with it like that. So the answer is no :(

The rules have changed since last year.

Rule R52 of 2013 allows multiple low-load motors on a single motor controller.

[Cal578]

The Team Update for 1-22-2013 added the snow blower motor to the list that allows sharing a motor controller. So, it is (now officially) true that all legal motors under 100W can share a controller.