Stepper Motors

I’d like to see steppers included in the rule set. Surely there are cases where they’d be useful, and it’d be a neat way to introduce students to a different sort of motor and control scheme.

I recall a turret on a robot from a few years ago that’d have been a perfect candidate for a stepper, as lost steps seem unlikely and the speed/torque requirements strike me as having been within reason for the smaller NEMA size motors out there. It’s been a while, but I’m pretty sure it’d have worked nicely. A closed loop brushed motor achieves the same results but in this case the stepper strikes me as the more elegant answer.

As a practical matter, I suspect it’d take a motor/controller combination that can achieve the same sort of holding torque that a window motor currently produces, and which is also reasonably compatible with FRC’s electrical and cost limitations. I have no idea if such a thing exists, but it’s probably out there.

Whether the benefit, which is mostly the novelty factor, justify the headache of sourcing them and the rule changes is another story.

Oh you want more power eh:
Same idea with external power MOSFETS
On a PCB

In fairness many window motors use a worm drive.
So the holding torque is really about how strong the gearing is.
As long as the stepper has the torque required to turn the worm gear.

Another way is to use a something like a dog gear to lock the mechanism at the stop point.
The advantage with the dog is that you don’t inherit the high worm gear ratio because as steppers move faster they operate with lower torque.

Then again could just use a clutch.

With the Neos and Spark MAXs, there is the possibility of a stepper motor control version.

For the Spark’s Trello Board, there has been the suggestion for stepper motor control APIs. All that needs to be done is up vote it to make sure that Rev recognizes the desire behind it.

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