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Unread 03-02-2012, 02:28
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Re: Converting 12v to 24v

Quote:
Originally Posted by PAR_WIG1350 View Post
Additionally, even by your questionably strict definition of a solenoid, the sectioned clutch image you posted depicts what is quite clearly a solenoid. one side of the clutch is connected to a V-belt pulley (green) the other side is (yellow) is the armature of the solenoid which appears to move on a double keyed shaft. The solenoid winding are stationary and contained within a frame (grey). When the solenoid is energized, the armature is pushed out of the center of the solenoid winding to increase the friction between it and the green side of the clutch. The windings are co-axial with all components of the clutch and are wound as a single coil around the armature. That is, the coil of the clutch is a uniform, tightly wound cylindrical coil designed to provide a uniform magnetic field within its core.
You may be right about the coil arrangement in the diagram. It could be toroidal, or it could be cylindrical, with several layers. If it is cylindrical, you could definitely have a viable solenoid within the bore of the clutch.

But, notice that the green armature does not reside inside the core of the windings. That's because it's arranged just like a conventional electromagnet (where the disc-shaped faces of the coil housing and armature attract), rather than a solenoid actuator (where the armature would be attracted/repelled by a portion running through the core of the winding).

And that goes back to the previous question: if we have a solenoid in an actuator, is it necessarily a solenoid actuator? If we have a decent solenoid in a motor winding, but the motor's principle of operation doesn't depend on the thing being a solenoid, is the motor a solenoid actuator? Same question here—even if we have a decent solenoid, the principle of operation of the clutch depends only on the external magnetic field. So why would this one be a solenoid actuator, if the motor isn't?

There's another layer of complexity: there's what I think, and then there's what I think a team could reasonably think. In this case, I think it's not a solenoid actuator. But I do leave open the possibility that a team might be under a reasonable impression that it is. (That would be highly dependent upon the situation, and the explanation and documentation provided.) I'm not saying this to be argumentative—I've got a better reason. It's the principle that a team that shows up to a regional having bought and installed an electromagnetic clutch should get the benefit of the most lenient yet precise interpretation of the rules. After all, the inspectors aren't trying to make teams fail—quite the opposite.

An additional layer of complexity is what the GDC thinks. As has been demonstrated repeatedly over the past decade or so, the Q&A operates on a different level to inspectors and teams. I'd venture to say it's a less practical level, and frequently a less creative level. Oftentimes a Q&A response will presuppose limitations that aren't logically required by the rules. Nevertheless, the inspectors need to balance what the Q&A is saying with what their understanding of the rules' demands. (When those conflict, there's an ethical decision that may involve equitable remedies outside of what the Q&A explicitly instructs.) I raise this issue, because what I say here (generally) represents my opinion in a vacuum, and not necessarily what I would rule in a competition setting where other factors (beyond the rules) are at work.

Quote:
Originally Posted by anthonyttu View Post
To preform (my understanding) what your trying to accomplish without breaking any rules or even flirting with any of them. You might look into pneumatic clutches. If your not using any pneumatic's anywhere else on the robot it might not be a good solution for your problem. Just an idea.
[R68] and [R71] would prohibit pneumatic clutches.