Hello, my name is Mark and I’m fourteen years old and I compete as team 2114B.
My Problem is when my Built-in-motor encoders get shocked by a static electric shock, they freeze my Cortex and it requires a reboot. There is a very long thread about this issue but I know the problem what I need to know is, if I put electrical tape around my 4-pin wires, will that solve the issue? A team told me this might help but I wanted to be sure before I went through all the work to find out it doesn’t work.
sincerely
~mark~ \m/ brofist
Hey, this is Nate from 127. Nice job at Nationals. We were watching both you and Automata.
We were having a similar problem with our IME’s. I got two answers from Karthik. The first is that this won’t be a problem at Worlds. They are spraying the mats with some sort of anti-static that will eliminate the problem. So, it shouldn’t be too big of a deal. I don’t think that he said we could put electrical tape over the ports, but there was some suggestions about using the actual plugs (either modified 2-wire or a four wire) to fill the hole. That’s what we’re doing, and so far it’s working fine. We haven’t had any shocks since we plugged in a cut-off four wire plug.
Nice to know my idea worked 
but karthik said tape would be legal also… and it should function the same as a plug just not as robust personally I am doing both of these taping every single IME and plugging the one hole just to be sure…
What if U.S. Nationals sprayed their fields with Anti-Static spray? :eek:
US Nationals did spray down at least at the very start of every day, and they might have at lunch. I heard they weren’t spraying more frequently because it caused the tape to loosen and because it took a lot of time I believe. Sourced from the refs I complained about drop outs to, and the giant bottles of anti static spray I saw while setting up.
Thank you guys for your answers! I am currently not using IMEs right now because of this problem and i need reliability. Just curios if this would work. Also, yes they did spray the mats down a LOT at Nationals. So much that I had trouble actually driving my robot! They did so Because of the boards they put down over the ice. It cause so much static it was unreal. I just hope this isn’t the case at worlds!
The only fields on ice were the practice fields…
Electrical tape will only help if the static discharge is over that location.
If the static discharge happens to travel inside the motor to the IME, the tape is not blocking anything.
I fear additional electronic parts are needed to solve this problem for good. Talking to an electrical engineer friend he had a few suggestions:
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TVS diodes in line of the wire going into each I2C port. There are diodes on the board Cortex right at the port inside the I2C port but I have no idea of the type of diode and the capabilities to clamp the voltage spikes. There is also a diode on the I2C part. I like this idea the best. TVS diodes are much faster than other types of diodes.
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Can we wrap the 4 wire in a magnet (like the motors have)? Is there external noise causing this problem too?
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Can ferrite beads on the signal lines help? This would be along with the tvs diode.
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Can we add an insulator on the bottom side of the circuit board (glue mylar on the bottom with a window for the sensor). Will this fall off and get gummed up in the motor gears causing tragic results.
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cover all the parts of your robot that may touch metal with non-conductive stuff like electrical tape. As these may touch the game objects and are in fact turly functional to stop a static discharge path from happening, I doubt this is considered legal.
As none of these are Vex High School/Middle School level legal, the anti static spray is your only logical point. Maybe some college teams want to try some of these ideas as they can play with electronics.
Awesome, thanks for your answer and suggestions :)! If only VEX could implement some of them… Though they did send out that E-mail that said they were coming out with a ROBOTC code to fix this problem. I just hope that is not TO long after worlds. (since they said it wont be out till after worlds)
Unfortunately these are hardware solutions… I could see a “dongle” you put into each of the I2C ports prior to a redesign of the I2C sensor and/or Cortex.
Any college teams want to try this?
It (unfortunately) really isn’t that simple. We’ve experimented with a number of solutions, and most of them just don’t work – some of them make things worse, since they impede the I2C communication.
Can you post what did not work or made things worse?
Did you try a torrid coil with 2-3 turns of the 4wire cable?
Thanks!