possible solution to the static problem

[David Brinza]

As I've previously mentioned in a related thread, an anti-static spray coating like ACL Staticide leaves a slightly conductive film on the surface of the regolith. It's available from McMaster-Carr (7090T37) in a 1-qt spray bottle, enough to treat an entire field. This product is designed to dissipate static charge on slick, non-porous, hard surfaces. If conductive copper tape were attached between the regolith and field boundary at a few locations around the field, the charge will have a path to bleed from the robots, down a chain, across the regolith, through the field structure, and finally to earth ground.

Perhaps someone can measure the change in coefficient of friction for regolith treated with Staticide. I suspect the change in friction would be quite small. The benefits of minimizing loss of comms, DS resets, replayed matches and even damage to electronics should offset a slight change in the playing surface.

[keehun]

Originally Posted by ZInventor

our team found out that our robot was a very efficient vann-de-graff generator ( we have super-fuzzy paint rollers spinning against PVC!!!, oh and di i mention, there are two, one at the top, and one at the bottom, with surgical tubin in between...)

Wow! Our robot is very similar in terms of generating static. Our ball collecting mechanism is many brushes made out of pneumatic tubing spinning really fast (like the front brush of many household vacuums) and we are generating a lot of static..

Originally Posted by ZInventor

i've been shocked many times, and at the PDX regional, several robots would drive across the field, hit the wall, discharge the static and die...

Die, meaning communications being dropped? Driver stations fried? cRio fried?

Originally Posted by ZInventor

I hope this whole fiasco is figured out before championships!!!!!

Hehe, I hope it is figured out before Week six events

But good luck to everyone!

keehun
Team 2502

[Al Skierkiewicz]

Dave,
I was up in Milwaukee last night and they reported using the static spray and had no problems that they could pinpoint as a static issue during practice. Milwaukee is on concrete and it was pretty cold up there so the heat is on.

[Pat Roche]

Sorry if this is a repeat I didn't have alot of time to post. We have begun using dryer sheets to wipe both the wheels and any lexan and/or plastic on the robot after every match. Thus far it has worked quite well to reduce the amount of static being carried by the robot. We have added it to our list of procedures after the match and only takes a couple of students a minute or two to do.

Just my $.02

Pat

[Matt C]

Originally Posted by Pat Roche

Sorry if this is a repeat I didn't have alot of time to post. We have begun using dryer sheets to wipe both the wheels and any lexan and/or plastic on the robot after every match. Thus far it has worked quite well to reduce the amount of static being carried by the robot. We have added it to our list of procedures after the match and only takes a couple of students a minute or two to do.

Just my $.02

Pat

Is also makes your robot "Springtime Fresh"!

[jerry w]

Originally Posted by Al Skierkiewicz

The regolith is also nonconductive. I would put it's voltage standoff rating in the tens of Kv range or better. Maybe I am missing something here, but I don't see how a drag chain could have any additional effect. When you use a drag chain over concrete, the material is conductive to some extent and likewise for carpet depending on the humidity and moisture content of the materials. The regolith is adverse to moisture absoption so it's electrical properties should not change over a weekend.

Let's not forget surface charges. As a material collects charge of a certain polarity, that charge spreads over the surface of the material. The chain brings the opposite charge down to the surface. This allows a restoration over time. Since the buildup occurs over time as well, we have an equalizing effect. The difference in charges will never become large.

Now that the trailers are using a drag chain, I would expect to see no large buildup on the playing field. However, the practice field remains a problem. The trailers on the practice field had no chain. Also, robots on this field have a tether cable attached. If charges are allowed to build, the driver station is subject to potential damage. an arc to the tether from robot frame is likely. the driver station has only minimal esd protection.

I have not heard credible evidence about cRIO damage. So far, there is evidence of only driver stations that have failed. I have seen and heard of only damage to driver stations and analog breakout modules. Other comments, here and elsewhere, have lumped the system failure as a cRIO failure. Please understand, i think WPI did a very good job of making a cRIO based system. it is simply not as rugged as the NI equipment.

(Also, spraying the wheels may work, but is against the rules. This lubricant changes the traction of the wheel.)

jerry

[writchie]

Originally Posted by writchie

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).

Neither static wicks nor drag chains were permitted by the inspectors at the Florida regional. I suggested to them, (and probably others made similar suggestions), that they consider drag chains on the trailers since that could remain completely under their control. Our drivers saw the chains on the trailers on Saturday.

I know that Team 2383 was having reset issues on Friday that disappeared on Saturday. They would reset every time they contacted a wall. This, however, could have been electrical rather than electrostatic.

I don't know if the "Trailer Drag Chains" have been tried at other regionals but it does appear that at least they do not make matters worse on the actual playing field, at least as far as Robot resets are concerned.

[AlexD744]

Originally Posted by writchie

Neither static wicks nor drag chains were permitted by the inspectors at the Florida regional. I suggested to them, (and probably others made similar suggestions), that they consider drag chains on the trailers since that could remain completely under their control. Our drivers saw the chains on the trailers on Saturday.

I know that Team 2383 was having reset issues on Friday that disappeared on Saturday. They would reset every time they contacted a wall. This, however, could have been electrical rather than electrostatic.

I don't know if the "Trailer Drag Chains" have been tried at other regionals but it does appear that at least they do not make matters worse on the actual playing field, at least as far as Robot resets are concerned.

I thought the drag chains worked really well for static at Florida. And reset isn't difficult if you have a list and each person does a specific job. For us coach and one drivers set up robot and trailer, the other driver set up the the control board and tethered BEFORE giving the other 2 the signal to turn on the robot and set autonomous. All the while our human player was taking his moon rocks to fill our robot's hopper. it was really smooth. Another thing to check is the radio ethernet cable. The programmers have to unplug it and sometimes forget to replug it.

[pitzoid]

Originally Posted by writchie

I don't know if the "Trailer Drag Chains" have been tried at other regionals

This was tested at FIRST last week and deployed to all week three regionals, the real test will be this coming weekend when there's another "ice rink" regional. There's weren't any week 3 ice rink regionals.

[Schmitty!]

I could be mistaken, but I'm pretty sure they had drag-chains on the trailers at the Wisconsin Regional also. (Al correct me if I'm wrong)

The Thursday practice day was pretty cold outside, so the heaters were on (which meant we were all walking ESD guns). I don't remember hearing any issues from other teams about loosing coms/reseting except on the practice field where the trailers didn't have any drag chains and the driver station was connected through the Ethernet port to the robot. We lost comms any time we activated a large sheet of fabric in our hopper.

Not sure if the presence of drag chains and no ESD issues was a coinicidence, but it seemed like things actually ran pretty smoothly once we got out on the competition field!

[Molten]

Drag chains were used at the boilermaker regional. No static problems that I saw or heard of. One team about caught their motor on fire, but has nothing to do with static.

[R.Mangum]

TEAM 122 Has been to DC and VCU. We have not seen or had any problems in practice or during matches. The robot has preformed as expected and has not need anything. After attending two events and not missing any practice or matches we are very happy with things.
Rick

[BHOP]

have we determined that static is the main cause for strange cRio resets while on the field?

I was just wondering because we ran into a strange phenomena while at the lansing district quarter finals. It left our alliance dead in the water, then soon after they had full field problems.

I would describe what happened as a huge hit between our robot and the side of the field, followed by what the field tech said was a cRio reset(they check the packets...)

this caused our robot to be disabled for about 20 seconds while it regained connection to the field. By that time we had all ready been "dumped" on, and plus our other alliance member was having some serious field related issues as well.

Anyways just curious if static was determined to be the main issue with this years game?

[Andy L]

The only problem I saw with our robot at SVR was our gaming adapter reset randomly after we hit a wall. Not sure if it was static though.

[EricVanWyk]

Originally Posted by BHOP

Anyways just curious if static was determined to be the main issue with this years game?

It was certainly in style to blame static weeks 1 and 2 for everything, and it was probably the cause for a majority of the problems. The drag chains seem to have fixed that. I was in Philly this weekend, and all of the robot troubles I saw on the field could be traced back to a non-static problem.

For example, one team had a piece of debris in their cRIO's ethernet port and another had broken off the retaining clip on the cable.