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Unread 12-10-2004, 20:23
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Re: How slow is too slow?

Hi, I was just looking around and run across this thread,
The poof's (254) and Kingman (60--my team) run a 2 speed gear box with a high gear of about 15fps and a low of 5fps.
This seems to give the best of both worlds, low-end power, top end speed.
As for driving, practice, practice, practice
Think of it as a car or a bike it's better to have the speed and power and not
use it, then need it and not have it.

gotta go
have fun
Geo.
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Unread 11-10-2004, 13:39
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Re: How slow is too slow?

That comment struck me too. Last year our bot went around 4'/s and that was good for the space we had to work with. I think I would have made it 5-6'/s in hindsight. But blinding slow to me would be 2-3 or less. Also our chassis was somewhat fragile to high speed impact - as Tytus rammed a goal during testing at high speed (around 8'/s) and put a 2" dent in the front of it. So we had to slow her down or we would have to put it on the rack after every match. I think if you want to go faster than 6-7/fps you better build it tough, cuz thats quite an impact you're going to make on the field and other bots.

Although this year we do plan to design for 9'/s
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Unread 11-10-2004, 13:52
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Re: How slow is too slow?

Our team has always made relatively slow robots.

Our winning robot from last year never went faster than 4ft/s. Yet it still achieved its goals consistently. Does it really matter whether you go 5ft/s or 15ft/s so long as you do what you do really well?
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Unread 11-10-2004, 14:07
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Re: How slow is too slow?

Ideally, you want something that can go 10+ f/s in high, and something like 4-5 f/s in low. The only example I can think of at the moment is my first year, 2002. My team, 810, designed a wheel/tread system (all credit goes to M. Krass for that), which was, if I remember correctly, 11 f/s in high, and 4 fs/ in low. In high, we could consistently be the first team to the goals, and in low, we could push almost any other team we were up against. Even more important, being rookies, we hadn't quite designed a hook that fit (weight requirements), so the extra speed was crucial in getting around the goals to push. I'd go as far as to say we could've even beaten 71 with that robot, but unfortunately, I never got the chance to go up against them, and that robot has since been destroyed (I wasn't exactly thrilled when I saw that).

However, 2004 my team had another problem. We had a single speed transmission, but the sprocket ratio on the wheels was off, so we had speed, but no power. We then were unable to turn. I'm not an ME, so I'm not sure if this is related to transmissions at all, but remember that you will need a good amount of power to turn any robot, because the carpet is a very sticky surface, so don't make your transmissions based on speed alone.
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Unread 11-10-2004, 14:21
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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.
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Unread 11-10-2004, 14:35
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Re: How slow is too slow?

Quote:
Originally Posted by Tristan Lall
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.)
The Martians' zippy little chihuahua of a robot was extremely -- and annoyingly -- fast. Its defensive ability helped take its alliance all the way to the top. Speed coupled with agility was definitely useful in the 2004 game.
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Unread 11-10-2004, 15:06
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Re: How slow is too slow?

Quote:
Originally Posted by Alan Anderson
The Martians' zippy little chihuahua of a robot was extremely -- and annoyingly -- fast. Its defensive ability helped take its alliance all the way to the top. Speed coupled with agility was definitely useful in the 2004 game.
Well, I didn't want to bring these up, because they're not representative of the typical strategies and designs employed by most teams, but I definitely see the advantages of this sort of thing. In addition to the Martian robot, 188's 2004 robot was also extremely fast and powerful. The Martians' gearbox was number one on my list of things that I wish I'd had a look at, because it was the only one out there that appeared to have comparable speed and power. (Was it a 3-motor, 2-speed design?)

My design (on Woburn's Blizzard 5) incorporated the six biggest motors in the kit, and a two-speed transmission good for 16 fps in high (really!) and 4 fps in low. The 16 was a little too fast (at the edge of controllability), but in the 2003 game, it would have been amazing as-is. We're always ready for the last war, after all.

Last edited by Tristan Lall : 11-10-2004 at 15:09.
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Unread 11-10-2004, 16:04
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Re: How slow is too slow?

have any of you played with or against team 60 in the last few years? and tell me that speed isnt a factor or even important.. or intimidating? haha

particularly 2002(OMG) 2003 and 2004


tho we all do remember 2002 71 BEAST (Still had a very important speed factor involved on those back wheels) and the match they finally had at national semi finals 2002


Maybe speed alone isnt super important always... but if you come up with something dominating once u get to where u wanna go then u want all the speed u can to get there to do it first


Osc's 2 Cents
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Unread 11-10-2004, 16:14
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Re: How slow is too slow?

Quote:
Originally Posted by SpaceOsc
have any of you played with or against team 60 in the last few years? and tell me that speed isnt a factor or even important.. or intimidating? haha

particularly 2002(OMG) 2003 and 2004


tho we all do remember 2002 71 BEAST (Still had a very important speed factor involved on those back wheels) and the match they finally had at national semi finals 2002


Maybe speed alone isnt super important always... but if you come up with something dominating once u get to where u wanna go then u want all the speed u can to get there to do it first


Osc's 2 Cents
That's not a byproduct of speed. That's a byproduct of fantastic drivers. 254 is the same way.

The speed helps, but without a good driver, speed means nothing, because you can't control it.
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