[Tristan Lall]

Originally Posted by Al Skierkiewicz

You forget the test we have used for this in the past. If it is a coil and something moves when you apply current, it is considered a solenoid/electric actuator. It is strictly limited by the GDC to limit the power sources that can be used on a robot.

I didn't forget that test...but I don't like the way it conflates a solenoid with an electromagnetic actuator as if they're necessarily the same thing. Here's an example of something which is clearly an actuator, but also clearly not a solenoid:

Originally Posted by Tristan Lall

Just for the sake of discussion, is this electromagnetic bell a prohibited solenoid actuator? (I would say no, because its geometry is inconsistent with a solenoid.)


From Wikimedia Commons

For the first time, it looks clear that FIRST wants to regulate all electromagnetic actuators (per the rule change noted in a previous post). But in that case, why not subclassify them as motors and non-motors? Is there something special about a solenoid actuator that doesn't apply to another kind of electromagnet that does mechanical work?

And while it's a convenient distinction, what would FIRST's rationale be for caring about whether a device does mechanical work or not? There's no correlation with electric power input, and there's no guarantee that a device not designed to do work is inherently safer than one that is.

Despite my concern with the rationale, given the rules this year, the way I think the test should work is as follows:

• Is the device electromagnetic and an actuator? If (and only if) so, [R48] applies.¹
• Does it contain a motor? Then see [R48A-I, K-L].
• Does it contain a solenoid? Then see [R48J].
• For electromagnetic actuators not otherwise mentioned, there is no specific permission (required because these are "[t]he only motors and actuators permitted"), thus they are illegal.

Following that logic, the electromagnetic bell (not a solenoid) above was legal in 2010, but is illegal in 2012. Similarly, an electromagnetic clutch which is not a solenoid is illegal this year (but would have been legal in some previous years). An electromagnetic clutch which is a solenoid is legal this year, provided it conforms to the solenoid rule.

¹ Despite its wording, [R48] appears to apply to electromagnetic actuators...if that weren't true, there would be a rules conflict for pneumatic actuators.