possible solution to the static problem

[Steve Compton]

Hey folks,

Not sure if all your static issues are wheels and airlocks; our (1391) experience at Jersey was something else altogether. Almost all of us are spinning some sort of insulator (rubber, plastic, urethane, etc.) around - quite often - another insulator (PVC or ABS rollers) and when they aren't enough alike .... whoops. We have created VanderGraf generators that send spike charges from the rollers into someplace or another that finds its way to where we don't want it to be.

During practice rounds, we watched our robot run for 25 seconds, then stop as the CRIO rebooted, then run another 10 seconds, reboot, etc. This was early on and no one else had run into this, so we began from ground (no pun intended) up back in the pits. Curiously, static wasn't considered early - we looked at current draws, 24V supply, voltage differentials, code, etc - anything that we thought might stop he processor cold. Eventually, at 7:45 in the evening, I disconnected everything, including motors, ancillary code, and hand manipulated our belt collector - bam! same behavior as all day. We could shut off the CRIO with me as the motive force.

By next morning we had: 1. rubberized our PVC rollers with DipIt spray paint (to make the roller more similar to our belt); 2. put a 3/8" aluminum rod across the frame that touched the roller (to dissipate charge rather than having it build up and spike), and 3. begun to spray our belt prior to each round with Static-Guard (yep, the grocery store solution.)

No more problems. Ends up the static spikes were traveling through PWM cable connections - can't expect any processor to handle that, other than to reboot. We built the static generator, after all. All the ideas mentioned previously won't deal with the delivery of an internal spike to the processor, so think through your observations carefully. I really don;t think frame charge is the issue - you did insulate your processor board after all, right? The processor was just doing what it was designed to do to avoid damage. The clue we finally had that it was PWM was that even when the camera was turned off, and we had disconnected the wires to the Victors (but not the PWMs), the camera's servos were 'twitching' the camera for a couple spikes before the CRIO cut out.

Hope this helps.