FRC488 2012 -- Gojira

[bleclerc]

About the Single/Double solenoids, this is something that is often confused, and I think I've gotten it figured out how best to explain it.

The solenoids control a valve that will let air come out of port A or port B. The solenoids should be called "Single with Spring" and Double. The valve has 2 positions it can be in, and the solenoids (and spring) are what switch the valves positions.

Starting with the Double, each solenoid is going to push the valve to one of the two positions, so we'll label them A and B for which port they push to. If you fire solenoid A, air will come out of port A. Once the valve has been pushed into one of the positions, the only way to change it is to fire the other solenoid (assuming you have removed power from the first). So the valve will stay in the last position you left it in (critical for our brakes to remain... broke? braked? after the match has ended and we lose power)

So the difference with the Single is that you only have one solenoid. There is a default position, lets say A for this. So the spring is always pushing the valve to A. The solenoid thus is what will change the valve to output to B. The difference here is that you must continue applying power to hold it there. As soon as you let go of the power, the spring will move it back to the default. The Double just needs a quick amount of energy to switch, and then you can stop powering the solenoid.

So the confusion often happens when you see varying amount of hosing coming out of solenoids. This is because the hosing come out of the valve portion. These are technically called solenoid valves, so it has two parts to it. All of our valves (and likely 90%+ of all teams) are 5 port 2 position valves. That maps to 1 input (P), 2 outputs (A and B), and 2 exhausts (EA and EB).

There are different types of valves you can use, but this does not change how the Single and Double solenoids work.

So the fact that the one solenoid we have marked as 2 only has one hose coming out of it is a result of the fact that we're using pistons that have a spring return, thus we don't need to power output B to retract them, and is independent of the type of solenoid and valve that we have there.

I hope that explains everything sufficiently

-Ben