Quote:
Originally Posted by Chris is me
Fast is good, yes, but that doesn't always mean a higher top speed. If you're starting in between the auto and landfill zone, going for the center of the step, you're driving five feet. At distances this short, you can easily gear your robot so quickly that you actually lose the race to a slower top speed robot factoring in acceleration. Even if it's just a few milliseconds slower, you're giving up low speed precision to have a high top speed you'll almost never actually reach. Acceleration models are available on CD to help verify this sort of thing, just keep in mind that the constants people use in these models vary.
What I'm trying to say is that you can't really spout out old "rules of thumb" as fact this year, in a game that isn't open field and for a different drivetrain configuration. Especially when you have never built a mecanum drivetrain. If you give advice without qualifying your lack of experience, teams may be led to make decisions they otherwise wouldn't that could end up hurting them. I've made this mistake before and i'm sure teams have made missteps as a result, hopefully minor.
This might be totally made up, but I've also heard that strafing performance decreases at higher speed gearing. This is probably a function of roller efficiency, if this is the case. I lack experience in this specific aspect of mecanum drives, though.
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I am factoring in acceleration. I use a drivetrain calculator that was on CD a year or two ago to determine the effectiveness of different speeds. Of course, the "speed loss constant" is somewhat of a fudge factor (80%), but that's hard to avoid. If somebody could supply the Kro and Krv to use, that would be pretty useful, as right now I'm just using the stock values.
Five feet is more than enough for a 15fps bot to gain the advantage over a 10fps bot, and as the distance gets larger the 15fps bot gets faster. The crossover point is at ~2.2ft, when both a 10.5fps and 15.0fps bot take ~.41 seconds. Of course my constants are probably throwing it off a little, but if you could supply your own calculated numbers that would be really helpful.
Because we will likely need to drive quickly at the start of the match/ auton, I feel like the minor time advantage we get at distances lower than 2ft is not worth it, especially because at those distance we probably don't want to go too fast anyway.