Quote:
Originally Posted by coalhot
If this is the case, why does a field with say three robots that exceed the cap happen to kill the whole field? It should only cause a single robot to cut in and out, right? Or am I missing something?
It's funny though, the camera seems to be the bane of all field issues so far this year (spotlighted by the FTA at NY regional having all the teams turn off their cameras for eliminations). What has changed between the past few years and 2013 that could cause issues like this, other than the bandwidth cap?
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You are quite correct that the vast majority of team issues are in fact problematic code on their robot. My point wasn't directed at you, but more at the general way that everyone seems to say "well, it's not the FMS so it must be your robot". The system is far more complex than that, and it's time we as a community start respecting that sometimes, just being not-FMS related does not indemnify FIRST from responsibility for the issue. Likewise, however, the issue IS very rarely FMS, and when it is the FTA can usually identify that.
I don't know why teams exceeding the cap are affecting the rest of the field. It's not my area of expertise, and the FMS whitepaper does give many details on how the bandwidth cap is implemented. It does not seem to be working correctly, or at least how any reasonable person would expect. The logical assumption is that all teams are allocated 7mb/s, and any team exceeding that will be throttled so as not to affect the bandwidth of the other teams on the field. Any usage over 6mb/s sees a sharp increase in trip time, and will result in possible control lag (presumably only for the team nearing their limit).
I would say that the camera is an issue primarily because of it's increased usefulness and the ability of teams to stream live feedback to their robots. In 2009, 2010 and 2011, this ability was not particularly useful and was note widely used. Last year, it was extremely useful for vision tracking or just for lining up shots. This year, I suspect even more teams have started putting robot-eye feedback, which seems to result in problems when several of these robots are on the field at once. The bandwidth cap may also be affecting things, since it limits each team to ensure that all teams will have an equal share, rather than dynamically reallocating bandwidth up to the maximum the system can handle to accommodate for a few robots using more than their even share.