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#13
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Re: Einstein 2012
I'm actually glad this happened on Einstein. Maybe this issue will get the attention it deserves. I feel terrible for all the teams on Einstein that had the problem though. It really is heartbreaking to see big name teams go down for no apparent reason and have the finger pointed at themselves as the problem.
Many teams have been plagued by this issue this year at the regional level. An issue that is mysterious and unknown. No explanation, and FIRST has been just brushing it off as robot problems. I think it has been pretty well documented here, and by the CTA that the issues do not involve a team's robot, but FIRST has not come out with any official documentation. Their stance to us about Bayou was that they would check the logs AFTER the Championship... Why the heck would they wait until AFTER the Championship to figure out our problems, or any teams with field communication problems? This should have been handled when the Regionals were going on to ensure that the issues would not come back. I expect FIRST to come out with an official statement. I don't honestly care that we didn't work in Bayou. What I do care about is our reputation as a team with a well-built robot that runs every match no matter what. We proved ourselves at the LSR, but Bayou, we couldn't run a single full match, and may times were bypassed and placed as a No-Show robot. The issue with us was not with the cRIO. Communication & Code lights went red, and we dropped the camera when we dropped communication. If it was the cRIO rebooting, we would still see the camera coming through. So that narrows it down to just one single device not working on our robot. The DLINK router. What is the DLINK dependent on to run? The 12V-to-5V converter, PDB, main switch, anderson connector, and battery. Those are the failure points for the DLINK dependancies. We ruled that out early in our diagnosis, and I'm pretty sure (actually 100% confident) that the teams that made it to Einstein had good power connections to their DLINK. It would be something if EVERY team on Einstein made it there with bad power going to their DLINK. I'm also confident that the teams on Einstein are established enough to make sure that their connections are good. That narrows down our problem to the DLINK router itself, and the field. Here's what I did to our router to try to stimulate our problem. In the pits at Bayou, I pulled our DLINK router off of our robot and slammed, and I mean slammed, slapped, hit, punished, the DLINK router against an aluminum extrusion on our robot. It did not fail a single time. Of course, we were hard wired, but that proved to me that the issue wasn't with the wiring on the DLINK. So now we have narrowed down our problem to the wireless components of the router, and the field. At Bayou, we were allowed to run our robot wirelessly, on a stand, on the side of the field on Friday night. You can bet we abused our robot trying to get the thing to drop, but we couldn't. It worked PERFECTLY. It had also worked PERFECTLY that same afternoon during lunch time. We also beat the crap out of robot then and didn't lose any packets or drop. This, to me, proves that it is not a robot issue. So what was different during those times? The crowd wasn't there. During lunch time, there were only a few people in the stands, and on Friday night, no one was there except us and another team that started experiencing some communication issues. I honestly think the air is saturated with radio signals. This is how I'm thinking about it. A radio wave is not any different from a light wave, right? Except on a different wavelength, right? You have a few white lights, but you're not worried about the white lights, what you're worried about is the flashing red light. It's easy to follow the red light when there are just a few white lights, but imagine if you have tons of white lights, and not just white lights, blue ones, green dones, ultraviolet ones, every color... Now try to follow the red light you started off with. It's impossible. And to amuse myself some more... different colored light is just a different wavelength. The channels and frequencies of radio waves of the routers we use, and the cell phones we use are no different. People much smarter than I am have figured out ways to filter out all these other frequencies, but there is a limit to how many radio waves there can be at a single time. I imagine that there were tons of people in the stands, wrapping around the field, during the Einstein matches. Each person (assumed) is carrying a cell phone. Many of them on laptops. Instead of having a faraday cage where no signals go through, you're concentrating all the signals from every cell phone to the field like a parabolic dish. Basically, my best guess is that the issues teams are having are interference. Why some teams don't have it, and some teams do is unknown to me. I noticed a big difference, minus the actual ability to connect and remain connected to the field that Friday night at Bayou. The difference was dropped packets. When we were on the field with 5 other robots and the crowd, we had very high packet loss and latency. When no one was there on Friday night, or even the one match we played on Thursday, when no one was there, we had very low packet loss and latency. |
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