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Ping time issues revisited

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  • Ping time issues revisited

    There have been multiple posts regarding connectivity issues on multiple fronts: ESD related USB disconnects, friction based connector disconnects, game controller to drive station phone disconnects, robot controller to REV hub disconnects, and wi-fi driver station - robot controller disconnects.
    Through use of proper device mounting/wiring, use of grounding cable, strain relief, etc., our teams and FTC as a whole have made significant improvements in addressing many of these issues, but much still needs to be done.
    At this past weekend's qualifier, several teams were plagued with high ping times. There is almost nothing students can do to address this. They can route wires better, take ESD mitigation measures, secure connections, etc., but they cannot control the wi-fi environment. Sometimes changing channels helps for a bit. Sometimes reboot of phones helps for a bit. Sometimes standing on your left foot and spinning 3 times counter clockwise while making a sacrifice to the master of hotspots helps for a bit. But nothing is definitive/scientific.

    We lost a match where our two teams were on an alliance together. The teams experienced 3000-8000ms ping time during the match - rendering bots uncontrollable. We lost the match - throwing an L to both teams for 1 of the 5 qualification matches. The match was against the eventual top team. We may not have won, but we would have definitely been competitive in a typical match. At the very least, the issue cost us a couple hundred tie break points. Frustrating!

    One team uses Samsung S5s as both RC and DS. The other uses Moto G4s. The team names differ by on character - so the network phone names do as well. An FTA suggest the two team's phones were affecting each other - I cannot follow the logic. These two pairs of phones have no more affinity to each other than to anything else on the competition floor.
    There were two non-FTC hotspots active during the match. There were also reports of spectators attempting to connect to the DIRECT-* connections - I guess so they could check their facebook or conduct some other "critical" activity.
    After the match, we took the bots to the practice fields (which were located ~25' behind the alliance location that we were on at the competition field - just behind some curtains). At the practice fields, we saw ping times of 75000ms!!! There was also the impression (real or perceived) that several other teams were having issues during this time - while playing at that alliance location.
    It was just after lunch break, and the practice fields were busy, and I know that there were several teams with laptops connected to robot networks - for OnBot or Blocks tuning - not sure if this affects anything at all - just an observation.

    FTAs tried to help, and we went through the typical steps - swipe off apps, reboot, change channel, 3 spin-one-legged-sacrifice-dance routine. Eventually, something "worked" and we returned to sane ping times. But there is NOTHING that teams can do to insure this does not happen during a match.
    It is insane to ask teams to spend months of development time - carefully using the engineering process to address issues in their design, construction, and performance - to then simply be left at the whims of such an environment.

    Please develop/publish some definitive mitigation procedures. Please develop solutions that allow us to progress beyond this. If we continue to use open WI-FI direct connections, something needs to be done to mitigate the issue - something to isolate the competition fields from the hotspots and from the dozens to hundreds of DIRECT-* networks of all of the primary and backup phone pairs of the teams at the event.

  • #2
    The G4's won't do 5.gHz, but I think the S5's should. That should help you out if you find a quiet channel.


    • #3
      Originally posted by korimako View Post
      The G4's won't do 5.gHz, but I think the S5's should. That should help you out if you find a quiet channel.
      How can you force the S5's to use the 5GHz channel preferentially?
      Technical Coach, Newton Busters FTC 10138, FLL 3077
      Chicago 'burbs, IL