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Unread 11-10-2004, 22:50
Steve W Steve W is offline
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Re: How slow is too slow?

Being from the same team as Tristan, I may be a bit bias. I did see a lot of games in that I was an announcer for 4 Regionals, Championships and an observer at 1 regional. Speed is good and speed is bad. If you can't control the robot at any speed then it is not good.

What I do agree with is that having only a 2 ft/sec difference isn't really worth the time to build or the weight that is generated. If you added 4 (double) to 6 ft/sec then the advantages could be seem and measured. IMHO our robot was a bit too fast for our driver (sorry Jon) but if he had more time to practice maybe it wouldn't have been. I did see a few matches that the dash from 1 end to the other was the reason that they won the match.

Right speed with right driver = success
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Unread 11-10-2004, 23:19
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Karthik Karthik is offline
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Re: How slow is too slow?

Designing a FIRST robot is all about trade-offs. Picture this pre-build season conversation, with a "Robot Dealer"...

RD: Hey you, strategy guy.
ME: Who me?
RD: Yeah you. Do you want a robot that can go 10+ ft/sec?
ME: Well yeah. Who doesn't? The extra speed can always come in handy. But wait a second, this is a FIRST robot. There must be a catch...
RD: Okay, maybe there's a catch. The one robot I had in mind has a one speed transmission.
ME: Hmm, no deal. I'd have to give up a lot of pushing power to be geared to go at that speed. Most FIRST games, require more torque than that gearbox would probably provide.
RD: HM, so you're one of those smart strategy guys. Okay, I'll give you a two speed gearbox. 10 ft/sec in high, 2 ft/sec in low...
ME: Wow, that'll let me be really fast and give me the ability to be a strong pusher I like that. But hold on. That sounds like a mighty big reduction. How much does that thing way?
RD: Fine. It weighs a lot. But I've got another one that weighs less and plays in the 4-10 ft/sec range.
ME: That sounds a lot better, but my drivers are pretty green. I don't know if they can handle that much speed.
...
This conversation could go on for a while...

The point is, speed is always an asset in FIRST game. You just can't give up too much to achieve it. I've seen many teams slave away in an effort to try and build the fastest robot. A lot of the time it's not worth it.

Remember, on a 48 ft field, there's not many times when you'll need to go much faster than 8 ft/sec. On the other hand, the ability move at 12 ft/sec, can be a huge asset. The decision you have to make, is whether or not it's worth the effort and weight to build in a function that may not be used very readily. This depends on your team's capabilities.

When it comes to the issue of control, I have seen some very fast robots which moved across the field with lots of precision. Team 25 in 2003 really sticks out in my mind. I've also seen some really fast robots slam into a lot of obstacles, and look like they've been driven by a drunk. More often than not, anything more than 8 ft/sec is uncontrollable. But with a nice PID algorithm and skilled, well practiced drivers, it is possible to control.

Would I build a robot that could only go 5 ft/sec? Probably not. I think it's very doable to build a simple two-speed tranny that puts you in the 4-10 range. This is a great range for most games. Remember, if your driver isn't comfortable with top speed, s/he can always pull back on the throttle. All that being said, there are many possible game designs that would cause me to go significantly faster or slower.
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Unread 12-10-2004, 00:04
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jonathan lall jonathan lall is offline
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Re: How slow is too slow?

I agree, 16 fps (give or take) was too much for that game, especially with the configuration of that robot. Not tipping every match required great care on the part of the drive team, and hard turning manoeuvres and dime-stops with the arms up were perilous (we never tipped ourselves, by the way). It was quite hard to control. Mind you, the freakishly high speed was useful once in a while.

Archimedes Match 53.

That being said, what we needed last year was a smaller gap between gear speeds; 16 is too high and 4 is too low. The truth is that everything is changed by a shifting tranny; that is, George1083 is absolutely right (with regard to his last comment), but only in the case of single-speed gearboxes. The truth is, limiting yourself to 10 fps (well, 10 isn't that bad, but 8 for example) in your high gear ratio is a severe limitation of your ability to take control of the field and in its nature limits possible strategies.

In any case, as the bottom line has always been, you can't tack on a speed to shoot for. We've tried to many a time on CD. As was demonstrated in this thread already, 639 and 60 were both winning robots with different philosophies. Setting a 'magic number' is just plain silly, especially for teams with the means to build really advanced stuff.
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Last edited by jonathan lall : 12-10-2004 at 00:06. Reason: Jeff posted about 53 at the same time. I guess I'm right!
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