Field Static Solutions
 

Hello All,

It was speculated that static build up and discharge from machines to the corner player stations (Airlocks?) could have cuased some field system issues at regional events this weekend.

The purpose of this thread is for people to discuss suggestions to prevent this in the future. lets share some of our ideas here.

I suggest that FIRST modify the trailer design to include a ground wire that drags on the floor under the trailer. The wire could be fixed to the trailer tounge where it extends into the trailer body. The wire would be under the trailer and not visible.

This would also create a uniform solution rather than asking teams to take chassis grounding into their own hands.

Any other thoughts?

Thanks, and good luck!

Re: Field Static Solutions
 

well, and what about driver stations?

Re: Field Static Solutions
 

There was an information sheet released awhile ago detailing how you should do this. it involved attaching a pwm cable to the bottom row of pins on the IO ports and attaching the other stripped ends to the closest screw.

as for the robot, we just bolted a piece of wire to the bottom of our robot. very easy fix, only took a few minutes.

Re: Field Static Solutions
 

Did any team with a non-metallic robot (wood, fiberglass, plastic, carbon fiber, etc) have problems with static?

Re: Field Static Solutions
 

I don't think the driver's station grounding wire is enough. It grounds the circuit to the case, but the case isn't grounded to anything. I think there should be a ground strap that clips onto the driver's station that's connected to an earth ground. Similair to an anti-static mat used when working on electronics.
Brian

Re: Field Static Solutions
 

I didn't have, nor hear about, any static problems at DC. Has anyone actually had problems with buildup, or are we discussing how to prepare against the pickle rebellion?

Re: Field Static Solutions
 

My team (964) bricked our station at the Buckeye regional, and there were a ton of other teams having issues with their system. The fix with the grounding to the casing worked, though.

Somewhat related, the Buckeye field controller used a cheap USB soundcard for the game sounds, and it was shorting out our system all-day Thursday. So lot's of static/ESD issues here.

Re: Field Static Solutions
 

Okay, thanks for clearing that up.

Re: Field Static Solutions
 

Well if you are Dean Kamen your "spritz" the field with water. At the NH regional the field operators were pouring bottles of water on field near the airlocks and Dean Kamen went around with a bottle of water spraying the airlock.

Re: Field Static Solutions
 

Squirrel -

I believe the issue is on the driver side, not the robot side. Robot A releases its energy to the field, but may impact any of the six.



For whatever reason, the FRP+rover wheel combination has some serious vandegraph potential.

Re: Field Static Solutions
 

A though was brought up by some of our team...

Ground the DS box to the field table so that we don't have the issue...

There were times when our robot hid the airlock and killed the system hehe...

But i agree with rob a grounding strap on the trailer would be ideal....

Re: Field Static Solutions
 

Increase humidity to 60%. The water vapor in the air helps make static electricity harder to build up.

Re: Field Static Solutions
 

For a drag chain or grounding strap to discharge a static charge on a robot it would need to contact a conductive surface. Regolith is nonconductive. Please tell me how this will help.

Re: Field Static Solutions
 

We had both alliance control stations die because someone would ram the stations and the grounding wire preventing the damage of the controls came loose. We went down for like an hour twice because of this. Also on thursday we had an average down time of 10 min. they fixed it for friday and it worked really nicely. Some of our mentors have mentioned that they do have grounders for people to keep you from killing your electronics after your robot builds us so much static electricity. We also had a lot of teams loose the control boxes for no reason. The NI guy who did a TON of work for the design and programing of the control system was really frustrated. Luck-fully for week 2 competitors most glitches have been worked out for you.

Re: Field Static Solutions
 

Kansas City had static problems, along with grounding issues on the main driver station junction box. The FTA stated that after several high speed collisions with the drivers station by robots the junction box grounding was comprimised.

Re: Field Static Solutions
 

You mean like this?

http://www.youtube.com/watch?v=o8Mv9LYRNcY

:cool:

Re: Field Static Solutions
 

Midwest was lucky this weekend with a high humidity weather pattern. Static did not look to be an issue. However, a variety of other issues did plague us throughout the weekend.
Draging a ground wire, as pointed out above, can do nothing to drain charge. There is no direct conductive path to ground and the wire or chain does not provide a large enough surface to capacitively couple into the earth below the floor.
My suspicion is that the power connector on the gaming adapter is not made for vibration. A hard hit to the airlock or field border or even robot to robot, could potentially interupt the power connection. It may take some time for the adapter to start sending or reboot on bad collisions.

Re: Field Static Solutions
 

Perhaps something like ACL Staticide should be tested on the regolith. McMaster-Carr sells this in 1-quart spray bottles (7090T37), which should be enough for an entire field.

If it doesn't change the coefficient of friction perceptively, but it eliminates static discharge, it should be applied to all of the fields before practice matches start.

Any teams out there willing to do some experiments?

Re: Field Static Solutions
 

Perhaps a mandatory dab of hot glue?

We have not had any issues with power connections during hard hits on our practice machine, though.

Re: Field Static Solutions
 

I'm sure by Tuesday's Team Update time they'll give the explainations and maybe some solutions. I don't know how Dean Kamen is in private but the way things were going in Manchester at the flagship FIRST event I would not blame him for being angry, but angry at what? Giving him the spritz bottle at least gave him something positive to do and walk off the frustration.

I hope someone is reviewing the tapes and seeing how the robots are situated prior to the field zaps. Thinking about it the air locks are the only metal to robot that may electrically connect to the Alliance station wall.

Our robot is a van de Graaf generator with it's vertical corkscrew design. We've grounded the metal frame to the floor but the floor obviously isn't taking it. A parent/mentor/electrician grounded our FRP floor, but only one 4x8 panel, on the small hope that the FRP can carry the charge across. There was limited success on that. Even just sitting in place spinning creates quite a charge.

Everyone knows to ground themselves before touching the driver station, and touch the metal frame before working on the robot itself.

Re: Field Static Solutions
 

Our robot has never built up any appreciable static, despite doing burnouts on regolith regularly during build season.

One of our patented good ideas this year was installing brushes on the frame that contact each drive wheel at the top of its rotation. Our intent was to keep the rover wheels clear of FRP dust and other debris to preserve maximum traction (and the brushes do that job very well - there is no dust on our wheels even after a half hour of skidding around on regolith).

Question: Could an unintended side effect of these brushes be that static charge is somehow dissipated and/or counteracted? My software-oriented brain defers to someone with a better knowledge of ESD...

Re: Field Static Solutions
 

I'm not an EE by any stretch, but would dragging a wire from your frame have the ability to turn the robot into a capacitor? And if so, then would metal to metal contact with another robot during a competition create the possibility of interfering with the link to the field?:confused:

Re: Field Static Solutions
 

Mark,
The robot already is a capacitor and dragging a chain doesn't change that since the field is an insulator. Without knowing for sure, the drag chain and staticide that has been applied to the carpet and the software changes for the FMS have minimized if not eliminated the problem. I am personally going with a static buildup as robots depress the regolith over carpet while driving as the cause of a charge buildup that uses the robot as a discharge path when it crosses the boundary. The staticide fixes that, and the drag chain if it crosses, adds to the solution. Don't fight success.

Re: Field Static Solutions
 

Thanks! Like I said, I'm not an EE however your plain english explanation was a help.:)

Re: Field Static Solutions
 

Staticide was used on the FLR field, but not on the regolith...I put it on the carpet.

Re: Field Static Solutions
 

The drag chains are doing the most. Most of the issue were bots with high speed conveyor and other type devices for ball control that were basically big Van Der Graph generators. They were very well insulated by the hard plastic wheels being used this year. Certain environmental field conditions make this much worse (like fields on top of ice rinks). The chains provide a ground path to discharge the large voltages that were building on the bots to the regolith and carpet discharging before they have a chance too short at the field boundaries. Not saying its entirely fixed, but things seem much better now....

Re: Field Static Solutions
 

Hey pitzoid - is FIRST now putting drag chains on all the trailers? I haven't seen anything in the update about it, and you're the first person I've heard mention them.

Re: Field Static Solutions
 

yes

Re: Field Static Solutions
 

Tom,
They have been on the trailers for the last two weeks as well as the staticide application to the carpet borders. They don't interfere with the game or the trailer movement and the trailer tongue is conductive to your robot unless you have chosen to insulate the hitch in some fashion. Your inspectors will be able to tell. There was no need to include this in a TU so nothing was contained in the last one.

Re: Field Static Solutions
 

We had the drag chains on the trailers at the NASA/VCU regional, but did not use the static guard on the carpet at any point during the competition. I never heard any of the teams complain about static issues, and this was the first year I NEVER got shocked by someone's robot.

Re: Field Static Solutions
 

Kyle,
The FTA was handling the spray. Is it possible it was done without your knowledge?

Re: Field Static Solutions
 

Don't forget that the weather is changing too. Our team has had major static issues with robots in the past (2003 was the worst), but they always cleared up in the first couple weeks of regionals as the weather got warmer and humidity increased.

Re: Field Static Solutions
 

I am 100% sure that our Static Guard spray never left crate #8.

Also, our field was over a basketball court, not an ice rink.

Re: Field Static Solutions
 

Here at the CT Regional, we have gone through 2 DS....but only when tethered. We feel we are discharging through the ethernet cable because there is no common ground. Once was when we were on the practice field....we were running our ball collector for a while, then went to move on the Regolith. At that point, comms dropped. A replacement DS was able to work. The second time was in our pit. We were running the ball-collector on the cart for a considerable period of time when comms failed again. Again, a replacement DS worked. We are trying grounding connectors between the DS and the robot. Our cRio itself is mounted on our wood chassis.

Any other thoughts out there?

Re: Field Static Solutions
 

At SBPLI today we had only one apparent ESD incident where a cRIO rebooted itself. Staticide has been applied since to the robot and there hasn't been a recurrence.
No DS's have failed on the field during a match due to ESD.

Spare Parts here has been busy with a lot of DS failures though (maybe ten), some due to physical ethernet port damage, but several I'd attribute to damage from ESD. Some may be repairable with a software reload, but I haven't had time to look at them.
Several DS's were dead when the team arrived and hooked up to the field for their next match. We swapped them out before the match started and haven't had a single robot forced to sit out a match.

We have not been wetting the carpet here, however, this is Long Island and it's normally humid. The weather, although cold in the mornings, has been warming during the day.

Re: Field Static Solutions
 

In the LV regional they told us to ground ourselves onto the aluminum before touching the DS or the cables. I have not heard of any DS's dieing here, although we may have gotten lucky.

Re: Field Static Solutions
 

The FTA for the Los Angeles applied Staticide to the entire field (regolith included). There was no perceptible change in the traction for the robots (as compared to what I witnessed in San Diego and OKC).

Al Skierkiewicz' comment above about regolith being a good insulator is true. When treated with Staticide , the trace amount of ammonium salt left on regolith surface provides a leakage path for the charge. The charge can now bleed from the robot, into the trailer, down the chain, onto the regolith surface where it is dissipated across the floor to the carpet, field boundary and finally, earth ground.

Re: Field Static Solutions
 

Solid grounding in multiple points might create other problems due to ground loops. You can get large currents flowing through low impedance paths that can create undesirable results. I think that bleed resistors (1-10 MOhm) within the robot will help avoid differential charging between the electronics and the chassis. FIRST is not recommending this practice until a better understanding of the problem and mitigation is reached.

Re: Field Static Solutions
 

I was FTAA in Connecticut this weekend. Well, there were some issues in Connecticut, but not with the FRP on the field. The chains seem to have done the trick. What was noticed is that driver stations, particularly made with FRP, or lexan were causing the most problems, We were spraying the carpet @ the drivers stations. Theory has it the while walking up to the station, the DR platforms were rubbing against the team member in charge of hooking it up. This created static in the FRP or lexan. When the power or ethernet cable were installed without prior grounding of the the human, the static was discharged from the FRP into the cable. We went through a few DS units.

Please ground yourselves to the driver station framework prior to touching either the cables, or the DS unit.