Static on the HDPE

[Al Skierkiewicz]

Does anyone who has built the ramp using the HDPE been experiencing static discharge to the robot? We have been able to reproduce a condition as the robot transfers from the ramp to the HDPE of significant arcing to robot metal parts. The static discharge wreaks havoc with the custom circuit and we are afraid that other damage may also result from the severe arcing.
The teams that have lost speed controllers, is it possible you have damaged the controller with a static discharge?
Let me know what you see during practice.
Thanks for any info...

[Joe Matt]

Nothing has happened from my team, but this is very wierd. I'll defanatly warn Chainsaw about this. But try to use some sort of metal transfer device such as a coat hanger to transfer the static away from the eletrical devices.

[Adam Y.]

Oooo boy I just realized something. Your robot could be turned into a giant ball of static electricity. My physics teacher showed it to us where he rubbed a piece of rubber solid rod (not unlike the tires First gave us) and rubbed it up against a plastic bag. This made the rod gain a charge. This is exactly what is happening with the robots. Lol only thing I could think of is ground the robot.
:edit:
Lol I just realized our robot will not have a problem. It is a metal frame with a wooden bottom that has electronics on it. The metal frame will act (hopefully) like a faraday box diverting the static electricity out and around the electronics.

[ebmonon36]

When we fried our speed controlers, they were on our wooden proto bot so it would have been hard for static to get to them. very interesting though.
eric b

[Jnadke]

Originally posted by Al Skierkiewicz
Does anyone who has built the ramp using the HDPE been experiencing static discharge to the robot? We have been able to reproduce a condition as the robot transfers from the ramp to the HDPE of significant arcing to robot metal parts. The static discharge wreaks havoc with the custom circuit and we are afraid that other damage may also result from the severe arcing.
The teams that have lost speed controllers, is it possible you have damaged the controller with a static discharge?
Let me know what you see during practice.
Thanks for any info...

Does this count as an external energy source??? lol... j/k


But, yeah, static can be rather hazardous... might want to look into enclosing/insulating that custom circuit.

[Dave Flowerday]

Originally posted by Jnadke
But, yeah, static can be rather hazardous... might want to look into enclosing/insulating that custom circuit.

We are of course taking steps to protect our custom circuit at this point. However, this is not merely an electronics problem. Several team members have received painful shocks from this.

[Adam Y.]

Several team members have received painful shocks from this.

Tell them to suck it up. Sure it may be 1000's of volts. Sure it may be painful but it won't kill them in a million years. As long as they do not get shocked while holding the robot.

[Dave Flowerday]

Originally posted by wysiswyg
Sure it may be painful but it won't kill them in a million years.

I hope you're kidding. Getting poked in the eye won't kill you either but FIRST still demands eye protection in the pits and on the field. A situation does not have to be life threatening to be a safety hazard.

You must have never gotten a good static shock. They can easily be powerful enough to cause pain in your elbow or shoulder that can last several hours or even a day or two. Now sure, this is mostly just annoying and nothing permanent, but it's definitely something I want to avoid in the future if possible.

[Adam Y.]

Yeah the problem is that there is nothing you really can do especially with the materials first decided to use this year. It quite literally is a giant physics experiment where you rub your feet on the carpet. It is even worst in the winter. I am sure the shocks will not be as bad as you can get with a van der gaff machine.

[Mercutio]

Originally posted by Al Skierkiewicz
We have been able to reproduce a condition as the robot transfers from the ramp to the HDPE of significant arcing to robot metal parts.

You can actually see flashes of light from the arcing? Yow!

If memory serves me, you have to rub against something pretty quickly to build up a static charge. I don't see how your wheels could spin fast enough to charge the plastic unless you are having serious traction problems. Have you checked on that?

[Dave Flowerday]

Originally posted by Mercutio
If memory serves me, you have to rub against something pretty quickly to build up a static charge. I don't see how your wheels could spin fast enough to charge the plastic unless you are having serious traction problems. Have you checked on that?

This is not the case. We have observed this situation with the robot in disabled mode. We manually slid our robot back and forth a few inches a couple of times (for a total wheel skid of maybe 6 inches on the HDPE) and pushed it down the ramp. The sound from the arc was loud enough that even one of our engineers sitting by the player station heard it.

Back to Al's original question: have any other teams noticed anything like this? Specifically how about Midwest teams stuck in this dry, cold weather like us?

[Adam Y.]

You can actually see flashes of light from the arcing? Yow!

Well actually you can see arcing even from little static shocks. It just depends on how dark it is.

Back to Al's original question: have any other teams noticed anything like this? Specifically how about Midwest teams stuck in this dry, cold weather like us?

Sigh all teams will soon experience this once they drive their robot. Rubber and plastic creates a static inbalance.

[Don Knight]

Darn, they've discovered our secret weapon.
Back to the drawing board the air thing still might work.

[DanL]

it's been a few days since this has last been touched, and the ship deadline is 2 days away.

Since several teams have confirmed it, this does apear to be a problem that FIRST should be aware of. Has anyone contacted them about it?

What about modifying the playing field to fix this problem? Meaning what if FIRST attached a grounding wire to the HDPE? My team hasn't had a chance to test this out yet, but I don't really want our all-metal robot to suddenly become energized in the middle of a match.

"Static Electricity" means "High Voltage"

When you scuff your shoes upon a rug on a dry winter day, your body typically charges up to a potential of several thousand volts with respect to ground. Touch a grounded object, and a spark will leap between the object and your fingertip. This kind of electric spark can only exist when a high voltage is present. The tiniest spark requires about 500 volts.

Yeah, if some teams have reported sparks, that's a problem. If we're sure that it's the HDPE, could FIRST fix the problem by attaching a ground wire to it?

[petek]

'Fraid you can't ground out a charge from a non-conductor like HDPE by putting a ground wire on it - the charge can't move through the plastic to the wire (that's why they use plastic for insulators).

The only way I know of to remove the charge would be to put an ion source (basically a high voltage source or radioactive element) near it. That would neutralize the charge on the HDPE, but it's not likely to happen here.

To prevent damaging electronics, we're probably best off discharging the robot frame with a ground wire before touching any of the wiring or modules. Another way is to attach a static wrist strap to the robot so that you're at its potential. One "benefit" of doing that is you could then zap anyone near by (since you're now carrying the same charge as the robot)...

By the way, I think we're probably looking at charges of over 20KV here.