Are your solenoids firing on their own?
 

Team 188 is trying to track down a pesky problem that ultimately results in SOME of our Festo Single Solenoids randomly firing once in a while.

Please post if you have Single Solenoids installed on your robot, and have experienced them randomly changing state, and meet the following criteria:

1) The solenoids that fire on their own are single solenoids

2) They only behave erratically when you try and keep and hold them in the energized state - if you keep and hold them in the non-energized state, they stay perfectly still

3) You notice the Spike controlling them DOES change state for no reason (The lights blip orange when they should be Red/Green/Off)

4) You can simulate the weird behaviour by quickly disabling your robot, then re-enabling it

5) Whenever the solenoid fires on its own, you notice that the Radio Modem light on the RC flashes red for a fraction of a second

I have posted another thread in the Control System forum, however I posted this message too because there may be teams desperately trying to troubleshoot what they think is a pneumatics issue.

-SlimBoJones...

Re: Are your solenoids firing on their own?
 

Are you dropping voltage at all?

Re: Are your solenoids firing on their own?
 

The Festo valves are air piloted, requiring min 30psi to operate properly.

If you are experiencing intermitent operation, you may be dropping below 30 psi at times.

Re: Are your solenoids firing on their own?
 

i dont know if it is the same with single solenoids
but we had the same poblems with double solenoids

our fixed was
take solenoid completely apart
take out piston inside
clean off gunk
replace internal piston
put solenoid back together

it will now work :D

Re: Are your solenoids firing on their own?
 

but does that explain the spikes?
i think you have a bad battery, bad connection to rc, or dropping voltage

Re: Are your solenoids firing on their own?
 

make sure the backup battery is charged/ plugged in because it will mess up communications between oi & rc....

Re: Are your solenoids firing on their own?
 

Actually, the RC will communicate with the OI without the backup battery. Just make sure the main battery is charged (with 11+ volts in it - you can check it by hitting the select button on the OI a few times). However, the 7.2v backup battery is reponsible for running the pwm signals to the victors.

As for the solenoid problem, it sounds like you have a short in your wiring somewhere, or maybe something wired to the spike/relay block wrong. Check all your connections, use an ohm meter to make sure theres NO continuity on your bot, and check the PWM/relay cables. It seems that we got a few bad ones this year. After you finish checking everything, find another electronics specalist on your team to check it over again.

Re: Are your solenoids firing on their own?
 

If you have a dead backup battery, it messes around with the RC. Also, when you mentioned about quickly disabling/enabling -- the RC sets every output to its default value (127 for pwm's, 0 for digitals, etc... I think), mainly for safety reasons.

In 2004 we used pneumatics to move our arm and, occasionally, the solenoids would rapidly flicker (you could actually hear it) when the joystick was moving/moved back to its center position. I just assumed it to be the joystick not fully returning to the center position, but in some occasions it just did it at random, regardless of joystick position. It never really bothered us enough to try and find the problem. But that only applies if you're using a joystick to control pneumatics.