Pneumatics Code

[Lord_Jeremy]

Originally Posted by Mark McLeod

A double solenoid would be kForward and kReverse.

Er, I think that would depend on the type of double solenoid you used and how it was wired to the spike. For instance the ones Team 1546 used last year (the same ones supplied in the KoP previously) actually had two sets of solenoid power terminals. To use one spike for both solenoids, you'd need to rig up a couple diodes. I think there's a diagram of what to do in regards to that somewhere around here. I don't recall if a different type of double solenoid valve was included in the KoP last year, so my advice may be out of date.

[nighterfighter]

Awesome guys, thanks.

I think I have some code that *should* work, I'll have to wait until Tuesday to find out...

Thanks for answering my questions, I ask too many. I get bored if im not in school, and if I can't actually test my code. x_x

[Mark McLeod]

Originally Posted by Lord_Jeremy

Er, I think that would depend on the type of double solenoid you used and how it was wired to the spike.

Yea, there are different methods of wiring the solenoid to the spike.
We only see one solenoid type in FRC. They are all simple coils that get energized or not, essentially, two single solenoids in one package.

Typically, the major variations you'll see in wiring a double solenoid on FRC robots are:

• Use two outputs on the Pneumatic Bumper w/o a spike at all (diagram 3 below). This is the easiest choice.
• Use diodes to direct the current flow from the spike to a either side of the solenoid (2nd diagram below). Jeremy's favorite method.
• Cross-wire the sides of the solenoid to a spike (first diagram below). This is the way I usually tell people to wire a double solenoid to a Spike.

All three methods work fine. It's just a matter of choice and circumstances.

[nighterfighter]

Hey, I got an idea!

Since I can't really know the pressure (without buying an expensive item...we are flat broke for this project. ) I decided to make my own gauge...thing.

I made a new integer, called compressorValue, and I will use that to store the value of the pressure left. I can do some tests, and see how much pressure is used by firing one shot, and how much is added in X amount of seconds of the compressor running...

But, this is where my question is. :/
Will the times change based on the pressure? Eg: Will it increase quicker at first, then increase slower as the pressure builds? Or is the compressor (the ones that came in the KoP) powerful enough that this resistance is negligible?

[Mark McLeod]

You'll lose the same amount of pressure each time, down to 60 psi, so that part's consistent.

Restoring the pressure is a function of how much pressure is already in the system. The compressor takes longer the more it has to work against higher pressure. So, for example, pumping 5psi back into a system already at 110 psi will take longer than pumping 5 psi into a system at 60 psi.

What you're suggesting will probably work for your purposes though. You don't have to be too exact. You can probably go with the time you measure when the overall system is down to 90 psi and you'd be fine. Then you could still check the pressure sensor for "1" and keep the compressor running as long as it doesn't turn back to "0".

[nighterfighter]

Cool, I wasn't too far off!

Looks like I have some system-of-equations to write tomorrow!