FTC- preventing ESD

[pyroslev]

Originally Posted by CENTURION

The motor controllers...have plastic enclosures already. So why aren't they isolated when used on their own?

How does the static actually get from the frame to the electronics?
And furthermore, how does it get from the wheels (Rubber and plastic) to the frame?

Your wheels/treads are sliding along on the tiles, the same way your socks slide along on carpet. This builds up a charge. Said charge is transferred into the frame through the metal drive shafts. The frame acts as a Leyden Jar/Baghdad Battery. The charge is not relatively high to the human touch but to electronics it is.

When your robot contacts an object with a differing charge, which can be the robot or a field element, the charge equalizes. Think about lightning. It takes the path of least resistance. Insert your electronics here.

If your electronics are mounted to the bare frame, your electronics provide a pathway for the static charge that has built up. The common path you'll see starts from frame to motor controller. The back of the motor controller has 4 metal screwheads. These when in contact with the frame are a direct line for that charge. (The Matrix Controller's screwheads are recessed almost a half inch)

Here the charge can cause the motor controller to lock up. This is not as common but it happens. If this doesn't happen, then the charge is sent to either the Samantha or the NXT. If it is the Samantha, it could lock up the Sam but it has ESD protection. This would send it down the USB cord. If the Samantha locks up, Only the power light will be on.

If the charge goes into the NXT, from the controllers or the Samantha, this can cause a lockup. The NXT has some ESD protection but it can't handle the charge your robot generates. If it fully locks up, the best the FTA can do is turn it off.

I learned all of this not from any one event or document. It's the culmination of a long learning process.