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Unread 11-10-2004, 14:21
Tristan Lall's Avatar
Tristan Lall Tristan Lall is offline
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FRC #0188 (Woburn Robotics)
 
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Re: How slow is too slow?

Quote:
Originally Posted by Joe Ross
I'm going to pick on Tristan Lall from this thread: http://www.chiefdelphi.com/forums/sh...02&postcount=3

I'm going to go out on a limb and say that 5 ft/sec is nowhere near blindingly slow. Sometimes, it isn't even slow at all.
One qualification to that statement: if a single ratio is all that you have, and you desire controllability and pushing ability at low speed, perhaps 5 fps is an acceptable top speed--but for a dual-ratio transmission, 5 fps (in high) is indeed rather slow, and doesn't take advantage of the potential to position yourself on the field at will. Even for a single-ratio design, 6-9 fps is more common, and significantly speedier (though of course sacrificing the pushing abilities).

In 2004, a high top speed wasn't used frequently, and the obstruction in the centre did limit the usefulness of much faster designs. (Not to say that it was totally useless, but 12+ fps wasn't hardly a priority.)

2003, however, is a better example of the benefits of speed: while you didn't necessarily have to arrive first at any particular position to win, it was often necessary to cross the field quickly to lend aid to your partner, or defend a stack, or gain momentum for a charge up the ramp. A low ratio is great for pushing matches, but with such a large, open field, a robot that could position itself at will was at a clear advantage.

In 2002, speed was a factor, but so was pushing. If ever there was a game for Blizzard 5's three-motor, two-speed transmission, geared to 12 fps in high, that was it. It's a toss-up.

So, for a dual-ratio design (like the one from the linked post), when you have a low gear of 3 fps, you won't derive any of the benefits of high speed by using a 5 fps top gear, because many robots will still be doing circles around you. In that sense, it is indeed much too slow, and likely a sub-optimal use of your dual-speed capabilities. For a single-speed transmission, a clear decision on speed vs. torque has to be made. In that regard, if faced with a 2004- or 2002-style game, you might want to use something slow and strong; alternatively, with a 2003-, 2001- or 2000-style game, something a little faster might be in order.

In essence, I would say that for a robot designed for the 2004 game, 7 fps would have to suffice for a middle-of-the-road single-speed gearbox, while 4 fps and (a rather quick, but still controllable) 12 fps would be best for a dual. For the 2003 game, I would tend to go even higher, with 9 fps for the single, and 5 and 13 fps for the dual.

One last item. I'm used to using multi-motor designs which can still push formidably at high speed. (Recall Blizzard 4 in 2003, which had a single-speed, 14 fps design, and could still handily out-push and outmanoeuvre [Canadian spelling ] most of the opposition.) I realize that many (indeed most) teams don't go that route, and therefore are more used to strategizing with slower robots.

Last edited by Tristan Lall : 11-10-2004 at 14:26.