Quote:
Originally Posted by Al Skierkiewicz
You are going way out on a limb here.
"If the bell or clutch was not a solenoid or motor, then it would not have been prohibited in 2010." The bell is a solenoid and so is the clutch you show. I have worked on a couple of hundred of these air conditioning clutches over the years. The clutch plate is pulled by the magnetic field set up by the electric current. The pull mates a frictional plate with a metallic plate to lock the pulley to the drive shaft of the compressor. If you stick your finger between the plates when you energize the coil it will get pinched.
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I don't dispute that it moves as you describe. We only really differ on the definition of a solenoid (and solenoid actuator).
I'm saying that we need to be discerning about what is a solenoid, lest low-quality solenoids like loops of wire be dragged into the discussion (an outcome nobody wants or believes should exist). I'm presuming that the uniformity of the magnetic field within the core is the distinguishing characteristic of a solenoid. Additionally, even in the presence of a pretty good solenoid, I'm asserting that it's not a solenoid actuator unless the device is using the characteristics of a solenoid (rather than an electromagnet in general) to do its work.
That leads to the distinction I described between solenoid actuators, and electromagnetic actuators (a broad class of devices that includes solenoid actuators and motors).
Quote:
Originally Posted by Al Skierkiewicz
"This is exclusive with respect to motors and solenoid actuators, but not exclusive with respect to actuators that are neither motors nor solenoids." What actuator is neither a solenoid or a motor or a pneumatic part?
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According to my contention, the bell, and maybe the clutch.
If you really want to get creative, I guess an electric actuator that is none of those things might take the form of a bimetal strip combined with a resistive heating element. When you raise its temperature, it bends to a specified position.
Actually, as we discussed earlier, [R48] certainly applies to (at least some kinds of) electromagnetic acutators, and certainly
does not apply to pneumatic actuators (because if it did, all pneumatics would be illegal, for lack of mention in [R48]). But does it apply to electroresistive actuators? (Or piezoelectric actuators, or static electric actuators, if such things even exist?)
Also, we can't just apply [R48] to all actuators not explicitly permitted elsewhere (like we might be tempted to do, to get around the pneumatic actuator problem). Then purely mechanical actuators (like a flyball governor) would be prohibited. Nobody wants that—and more importantly, it would be a non-obvious and perhaps even unfair restriction to enforce at inspection.
Quote:
Originally Posted by Al Skierkiewicz
"Though admittedly the rules aren't clear about this, for 2012 there isn't really any reason why any motor couldn't be considered a custom circuit...there's no significant discrepancy between the motor requirements and custom circuit requirements. I doubt this is necessarily what FIRST intended, but at least it doesn't conflict." How can you draw this conclusion from both the motor list that you state is an exclusive list (excludes all motors not on the list) and from the custom circuit rules which prevent any custom circuit from direct control of a motor?
[R47]
Custom circuits shall not directly alter the power pathways between the battery, PD Board, speed controllers, relays, motors, or other elements of the Robot control system (including the power pathways to other sensors or circuits).
So what exactly are you thinking could appear on an FRC robot that is neither a solenoid nor a motor nor a pneumatic part, that would be in your mind, a legal actuator?
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That's the rule I had in mind—you can't alter the power pathway
between the device and the power source, but you can alter the pathway
inside the device.
If "between" was meant to include the device itself, it would be impossible to make custom circuits that draw power from the robot. Normally it's moot, because you can't really alter motors legally.
But there's no actual conflict between the motor/actuator and custom circuit rules that prevents a device from simultaneously satisfying the requirements for both.
I say there's confusion, only because I don't think that's what the GDC intended, and it may be worth asking them "if a device is (or contains) a motor or other electric actuator, does that exclude it from being a custom circuit".