Van De Graff effect on shooter
 

This is part question, part help...

Has anyone else experienced any EMC issues with their shooter wheels? We spent alot of time calibrating our shooter / camera combo today, and we were running the shooter alot.

We had shot several hundred shots, when the radio starting cutting out.

After the electrical team spent time figuring out what was up, and working on the EMC type issues, we had our answer.

We've made a 120 lbs, mobile Van De Graff generator. Foam balls, foam rollers, plastic wheels, PVC frame, and high RPMs... And once we came up with this theory, everyone started remembering... "Hey, that's why the robot shocked me!" and "Oh yeah... that explains the shocks."

Anyway... anyone else experience this???

Re: Van De Graff effect on shooter
 

yeah i think i noticed this a few times on our bot too. very keen observation

Re: Van De Graff effect on shooter
 

You could use this property to your advantage.... "Accidentally" give other robots a massive electrical shock... or judges.....

Re: Van De Graff effect on shooter
 

We haven't had this problem this year but last year every time we would walk away to get a part and return while it was being worked on we would get a little zap and could see the sparks from fingers or metal tool to the robot. But this was totally the effect from a very dry room and very old, dry carpet. Solved this by making the floor damp. Maybe you need to wipe down your PVC?

-Mike

Re: Van De Graff effect on shooter
 

That would explaint the increased snaps.

Normally, we get little shocks. However, the snaps are like lightning bolts. We attributed it to static electricity and the cold, but thist makes more sense.

Re: Van De Graff effect on shooter
 

I've been getting that too, even before the robot was being put together. It was weird, I thought it was just part of global warming or something. The increase in static electricity in the environment. (I've been watching too many dooms day movies)

Re: Van De Graff effect on shooter
 

I thought Icarus was shocking me more than any of the other robots did. :rolleyes:

Re: Van De Graff effect on shooter
 

FYI, before touching the electronics, touch your robot first and discharge the static.
If you use plexiglas or other polycarbonate parts you will notice that they get dirtier faster from the static build up.
Static plays havoc with electronics. I should know, I work in electronic control board factory and we a VERY conscientious about static ESD shoes, and smock). Our floor is a special ESD floor.
I wonder if FIRST will let us use a drag chain on the bottom of our robot?

Re: Van De Graff effect on shooter
 

Time to stea - uh - liberate some static spurs from the plant.

Damaged Electronics
 

Our robot likes to shock people too. It has knocked out three encoders and a speed controller. We are experimenting with drag chains to transfer the shock to the carpet. I cannot imagine FIRST banning them. After all, it is within the box. Last year our robot had a chain hanging down to allow our robot to be touching the inside of the triangles.

Re: Van De Graff effect on shooter
 

It seems to me that if you have accidentally created a van de graff generator then you are making an area of high and low charge. put some metal bristles that contact the areas of high and low charge and connect them through a wire.

Re: Van De Graff effect on shooter
 

Rick,

Most probably the offsetting charge is in fact being shot out of the robot in the form of foam balls. Which makes one wonder if enough teams doing this could start building serious charges up on the balls themselves. And thus start tossing around small foam lightning bolts.

Re: Van De Graff effect on shooter
 

Yeah, our robot wacks us pretty good. The charge is building up in our metal frame and pvc and it's knocking out the radio connection when it discharges.

Here's my theory, the metal on the DB9 connector is the ground shielding of the cable, so it is the easiest place for the charge to jump to. The radio is mounted so the connector was 1/4" or so away from the pvc or metal frame. We put some electrical tape on the exposed metal on the DB9 connector that plugs in to the radio, hopefully this will insulate it enough.

Otherwise we will try dragging something on the carpet or suspending the radio in some sort of zip tie web so it is not hard mounted to the pvc or metal.

Re: Van De Graff effect on shooter
 

You would think that FIRST would have thought of the electrical part with the foam balls. I mean sure they could say it was a twist we have to deal with.

However, we have been getting some portions when our radio gets "stuck" not working. This is the first explanation that makes any sense. We have even gotten some weird RC errors.

Re: Van De Graff effect on shooter
 

To correct myself, after further testing we too had this problem, during testing saturday night my dad had his finger just slightly off the edge of the Aluminum frame and would get a zap about every other ball.

Likely in purdue we will try a dragging chain or something. It seems it would be VERY bad for the controler to have all this static.

-Mike

Re: Van De Graff effect on shooter
 

Would dragging a chain on the carpet do any good? All the teams have rubber wheels or tracks. That generates static too :ahh: Like walking across carpeting and touching a doorknob. Some of the regionals will be held in the north where humidity is low during the winter, there will be allot of static.
I wonder what it will be like when two robots touch :yikes:

Re: Van De Graff effect on shooter
 

*ZAP!* Oh, shoot, my RC went out and all my electronics are blown! :D

Re: Van De Graff effect on shooter
 

Our robot actually generates terrifying/amusing arcs between the front roller and chassis after we shoot a few balls.

Re: Van De Graff effect on shooter
 

I have never visibly seen it but I have felt the small shock I hope the robots don't become like tasers on wheels or something... *shudders* (at zapping possibilities) It might be cool if no damage results from it though...

Re: Van De Graff effect on shooter
 

so drag chains would possibly work? ok umm wire is lighter i think would wire work dragging on the carpet? so stick the wire to the grounding bolt then down to the ground? am i right here?

Re: Van De Graff effect on shooter
 

I am fairly certain wire would work if you weighted it with a nut or something.

Re: Van De Graff effect on shooter
 

if you drag anything on that rug you will get even more of a zap. you need it to be "grounded" and you will not get that on the field. unless you run up and touch the rail system to get rid of the energy.

Re: Van De Graff effect on shooter
 

I dont know how it will be at actual competition but at the DC scrimage there were massive amounts of static built up on the railing for the OI stations, i have decided that if i get roped into driving im going to were my antistatic wrist strap to keep from getting shocked too much, but for grounding just connect yourself to as many different things as possible so that the relative charge of the area is 000000.0000

Re: Van De Graff effect on shooter
 

Team 213 did experience this, in our collector, which is a large belt that is stretched across 2 PVC rollers, and has few pieces of aluminum that are inside the belting, reaching across the belt and contacting for about 18 inches. We first discovered it when we tested it by hand, cranking the belt manually, and the designer got shocked. I think we managed to eliminate most of the charge buildup by taking most of the supports away, but it remains a running joke for our team.

Re: Van De Graff effect on shooter
 

In the past four regionals did anyone have a problem with too much static? I mean with the robot not the other teams :D

Re: Van De Graff effect on shooter
 

Actually, our FVC robot builds up immense amounts of static - more so than our FRC robot does. Maybe it's the driving across a foam-padded floor, with rubber tires, and intake rollers made of plastic that pick up rubber raquetballs... :yikes: I guess they'll have to carry around one of these now...

Re: Van De Graff effect on shooter
 

Yes, but where would you attach the grounding end? I know, a FRESHMAN :D