I was recently testing some new additions to my robot and I realized that when I grabbed the bot the metal discharged some electricity. The discharge wasn’t near the sensation of rubbing your feet on carpet then touching a metal handle, but it was still noticable. I ran the robot some more and it kept on discharging each time. I replaced the battery and checked all the wires, but all connections were good and no wires were exposed. I am using omni wheels, and while using them may cause some static electricity I wouldnt think that it would cause that much static.
I was wondering - Have any of you experienced static discharge like this? Are there any ways to discharge it that you can think of?
Our team got foam mats to practice on, and occasionally after you drive for a couple minutes, you get shocked touching the bot. Maybe touch the robot with a metal key before touching it with your hand - it should still discharge, but it won’t zap you (I think).
Thanks a lot. I just worry that 1. It’s something I could prevent, and 2. The extra electricity could mess with electronics and cause some serious damage.
It’s happened to us before, however, in general unless we zap the brain directly it hasn’t caused major issues. If the bot starts driving funny though, we immediately reload mastercode + user code and that has fixed it every time we’ve had a problem.
It happens a lot during the drier parts of the year and as far as my team knows, there’s not much of a solution besides carrying a small piece of metal so that you don’t get zapped painfully.
Moving plastic wheels can act as a Vandergraaf Generator and Leyden Jar when driven on rugs or other surfaces. Try attaching a bare stranded copper wire to the bottom of the steel robot frame so that it is dragged along the floor to discharge any static electricity that has been stored by the plastic wheels.
If you want to protect the VEX Controller from static, you could enclose it in a Gaussian sphere or Faraday Cage as Nikolas Tesla did when he protected himself from artificially generated lightning. This is accomplished by gently wrapping the controller in aluminum foil paper, making sure not to short any of the connections to it or by building a steel box from VEX metal parts to enclose the VEX Controller, leaving just enough space for the cables to motors and sensors.
Is there a definite cause or way to prevent it? I rather not have to reload master code every time it runs or have the circuits messed up in the middle of a match, not to mention building a cage and stuff isn’t really preventing but rather avoiding. I know dry air doesnt help with static, but it shouldn’t be nonexistant one second and suddenly appear once I add a new drive system with the same electronics and metal. Also, I know with carpets and such static happens, but I’ve only been practicing on foam tiles, and I don’t really think omni wheels on foam tiles should cause any static (if they do, then I’m surprised others haven’t mentioned having this problem). I know one member had a thread a while back, but as always they said to ground it - I cant exactly “ground” in the middle of a match, and it shouldn’t be happening in the first place.
Has anyone else experienced static, or have any ideas why/how it’s happening and how to get rid of it?
What they did in FRC to prevent discharge is to place a small amount of chain connected to metal (small enough to touch ground but short enough so there is no risk of entanglement), this is good for practice, but idk about competition. They also did things like spray a little water on the field (proly not good w/ foam) though a dry climate is probably the problem. I live in Hawaii where the humidity is usu around 80% - 100% so I really don’t have this problem. I think they would allow you to run a small wire or chain as long as it doesn’t hurt the field…
Plastic wheels on non-conductive foam are a very good electrostatic generator. You are better off practicing on a hardwood or concrete floor. Another idea to protect the VEX Controller electronics is to enclose it in an anti-static bag used to protect PC circuit boards.
Ok, so we’ve settled that wheels+foam+friction= STATIC, and it’s something many people have experienced (esp. in dry climate). Now, we’ve discussed some solutions, but dragging wires, humidifying, etc. is still just avoiding it. I’m already qualified for Dallas, and their humidity is significantly lower than here in Baltimore, so static is potentially going to be higher.
Does anyone (IFI, community, etc.) have any solutions that would be competition legal and would work to eliminate the static? I don’t want to be in the middle of a match in Dallas and have my only microcontroller fried (not to mention, although tolerable, getting shocked is an unpleasant side effect).
Make a dangly thing out of vex metal and let it drag loosley on the ground. Or, you could try using the wire and tell the inspectors and everyone that it is just for safety. If the inspectors thought that it might give you an advantage, for whatever reason, you could let everyone use the wire (everyone would get the same “advantage”, right?) I don’t know, I never did comp, I don’t know how picky the judges are.
Mount a water bottle, jet spray and electric water pump to the robot and have it humidify the air as it moves about in the contest arena.
Spray conductive aluminum paint or glue Iron Filings onto all of the the robot’s plastic wheels and have a fine copper or brush attached to the robot steel frame and each tire to act as a conduit to ground for static charge.
Make sure that the foam mat is conductive and is grounded to a water pipe.
Wrap foil paper around the VEX Controller and also wrap foil paper paper around each wire leading from the VEX Controller and ground it to the robot frame.
Don’t use non-conductive plastic or rubber wheels (they insolate and store static)
Before handling the electronics, ground your self to a grounded water pipe or metal object since you may be building up the static charge or wear a ground strap (This is basic ESD protection).
Sounds reasonable. I shall test it tomorrow when I finish upgrades.
As for Tswift’s reply, I’m pretty sure that most, if not all, of them would violate competition rules, so…erg.
Also, how would foam, an insulator, be able to ground the static? I understand that it can build up charge, but wouldnt grounding into an insulator not work? Plus, wouldn’t dragging a metal wire help generate more static?
Just to be sure, are you driving your robot on the right side of the foam mats? One side is squishier than the other, the harder side is he official side. It would seem that if you’re driving on the squishy side, it can generate great amounts of static elec. but not the relatively hard sides.
My mats have a smooth side (like the fields) and a side with bumps on the surface, and I practice on the smooth side due to the similar texture on the field (and if that side produces static, then of course it will in competition).
The regulation mats have a hard, bumpy side and a smooth, softer side. The smooth side is the playing surface.
I’ve never seen static, but all of my experience has been in the Pacific Northwest and at Worlds, not in New Mexico or Colorado, so I am ill-equipped to discuss dry climates. Dallas in April is not particularly dry, in my experience.
There is such a thing as conductive foam used as a packing material to protect circuit boards that contains carbon, which is a good conductor.
The only component you really need to worry about is the VEX Controller. Just enclosing it with some VEX metal parts would go along way towards protecting it from ESD.
Well, after looking up the materials for the foam, ends up many of them are made up of ethyl vinyl acetate foam. Interesting property - ethyl vinyl acetate is waterproof, and is added to plastic wrap for additional “clinginess.” Hence, this foam is perfect for STATIC. Also, supposedly several forms are conductive, so hopefully I can manage to make a low-friction metal runner to dissipate some static.
I am an expert at getting zapped.
I found that you can just use a key and touch the metal and discharge without any real problems. In fact, I have never had any problems from static electricity besides a little bit of discomfort, so I say it’s safe to just use a key.
