Apparently a beaded brass drag chain is not prohibited:
http://forums.usfirst.org/showthread.php?t=12284
But a static discharge wick on the other hand is expressly prohibited:
http://forums.usfirst.org/showthread.php?t=12228
Go figure. I can't wait to see the engineering explanation for this (or has marketing taken over
)
We will be installing a drag chain based on this ruling. It appears to be the only pro-active static mitigation method permitted on the field (other than dealing with van de graff generators on the Robots).
Chain has the advantage of guaranteed contact with the floor and the disadvantage that a corroded link could cause a high resistance in the discharge path. Movement should mitigate that and the charge can be passed along bead to bead, not to mention that the chains will be new.
The static wick has the advantage of guaranteed continuity but the possibility of becoming no longer in constant contact with the floor.
All in all, I think 79's chain solution is probably the best.
Unfortunately, protecting your own Robot in this manner may not protect you on the field when you contact another robot. If a large charge is allowed to build up on one robot, the discharge transient could possibly end up resetting either cRIO.
Also, it may be a good idea to insure that all power and signal leads have as great a distance from bare chassis metal (and charge generating materials) as possible. Normally, we only need to worry about short circuits. In the high ESD environment, we also have to worry about jumping the spark gap. A 10K charge can cross a 3MM gap.
BTW, it doesn't matter to 75% of the teams what solution is in place after week 6.
IMHO a quick fix that should be explored is to modify the trailers. There are only 6 trailers on the field and 6 drag chains are relatively easy to install. This is an easy fix to install, easy to test, and doesn't involve teams having to scramble to do something. It can be done during practice matches. Split the regionals, put chains on half and not on the other half and then correlate resets, chains, and humidity. If it makes things worse, it will do that for only half of the practice rounds. If it makes things better, it will do that for half of the practice rounds. (I'm ignoring the DS issues - they are a different matter).
The good news is that it looks like the cRIO is proving to be solid and the worst case result is a reset. There is probably no way to do better than that with everything floating. I'm extremely impressed by the cRIO. Great Job NI! and thank you for supporting FIRST.