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Originally Posted by Arkorobotics
First off this needs to be controlled by a VEX set, and it can't exeed 13V even when you wire them to give you 39V.
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Now you know why the FIRST rule-writers have such a headache when they release their rules.
You didn't specify total system voltage, you said "Max Volts on battery". That implies the singular, so 13 V per battery, 39 V for the system seems like a reasonable assumption—unless you're saying that the battery is a collection of up to 3 smaller batteries (that's possible, given the definition of a battery as a collection of connected cells, but represents rather unusual word usage). Also, I'm not sure whether you're looking at the rated voltage on the battery, or the actual measurement at the terminals; these, of course, can be different. Furthermore, if you are looking at rated voltage, a battery can be hotwired to put its cells in series; if you have a battery that is rated with parallel combinations, an enterprising person could rewire it so that it runs at a higher voltage. (I'm sure that that violates the spirit of the rule—but it can't hurt to be specific.) Adding a modifier like "total system voltage is to be measured immediately before the test, and must not exceed 13 V" (or "39 V", if that's what you meant) would simplify matters.
Similarly, the current rating is ambiguous; is it peak system current, or something else? Is it measured at the battery, or at the output devices?
And, if one really wanted to mess with the rules, one might attach a step-up circuit to the battery, to provide some large voltage to the motors at low current. If the current rule applies at the outputs, this could theoretically be somewhat useful.
And as for energy input, I assume that a push start is forbidden, but what about a ramp start? That's the robot's gravitational potential energy being used up, rather than the robot's electrical energy. (Incidentally, the batteries are a form of chemical energy storage; surely you don't mean to exclude them under the no chemicals rule....) And while we're at it, you didn't say that capacitors aren't allowed—say hello to my 100-
aerogel-capacitor array at 250 V; who needs a battery? Similarly (though they wouldn't be too useful), photovoltaics aren't restricted either.
And if you really want to get "out there", and had a budget to match, there's no specification as to the nature of the test surface. If I happened to have, for example, a few thousand Nd-Fe-B magnets, and a very long evacuated metal tube, I could fashion a maglev vehicle powered by a linear induction motor. I wonder how much energy one could store in 10 pounds (less the VEX controller and motor) of ultracapacitors? It's an inside-out railgun operating in a vacuum, so it ought to be interesting to play with.
I'm not picking on you. I'm thinking of alternatives (even crazy ones). So, if you're writing the rules, you need to plan ahead, or prepare to be surprised with what people come up with.
By the way, his system seems like it could be controlled by a VEX set: VEX RC -> servo -> linkage -> light switch (which connects motors).