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Unread 11-10-2004, 13:36
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Re: How slow is too slow?

Lets put it this way, every year there has been at least one very good strategy that did not need a fast robot.

2001, perhaps the year that had the biggest point advantage for being fast, required a lot of finesse balancing the bridge and most teams did not gain much by being ultra fast.

2002, It didn't matter if you got the goals first, only if you had them at the end.

2003, vision was the limiting factor in clearing out all the bins from your opponents area, not speed.

2004, you could very easily herd balls and cap and then hang, without ever traversing the field. If you held the balls internally, you didn't really have to be fast at all.

In every single one of the gearbox threads, someone asks "how fast is it?" That means that someone has ben thinking about desired speed. Why not think of it from a strategic viewpoint (note the forum) rather then purely a gearbox viewpoint?
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Unread 11-10-2004, 14:17
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Re: How slow is too slow?

Quote:
Originally Posted by Joe Ross
2002, It didn't matter if you got the goals first, only if you had them at the end.

2003, vision was the limiting factor in clearing out all the bins from your opponents area, not speed.
For 2002, note that the winners of a lot of events grabbed onto the goals first and didn't let go....speed was a factor *cough*71*cough*


Also 2003, unless your machine had a combination of speed and strength if you watch a lot of the matches as the year went on, a majority of bins stayed on the side of the field they originally fell towards. If those bins fell against you, you better have been fast enough to get as many of them over to the other side as possible

I definately think speed was a major factor in those 2 games...
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Unread 11-10-2004, 16:18
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Re: How slow is too slow?

Quote:
Originally Posted by Joe Ross
2001, perhaps the year that had the biggest point advantage for being fast, required a lot of finesse balancing the bridge and most teams did not gain much by being ultra fast.

2002, It didn't matter if you got the goals first, only if you had them at the end.

2003, vision was the limiting factor in clearing out all the bins from your opponents area, not speed.

2004, you could very easily herd balls and cap and then hang, without ever traversing the field. If you held the balls internally, you didn't really have to be fast at all.
2001....then entire game had to do with the speed with which you did something. If you got from point a to point b faster you had more time to work with balancing or whatever.

2002....dj already made my point

2003, you may not have won, but if you knocked the bins over quickly (quickly....nice pun) you shifted the game to one side dramatically. The rest of the time the other team had to play catch up....

2004....defensively, speed was a huge factor (who did 71 pick first in atl? oh oh 494 that's right)

I think some people underestimate what being the first to the punch can do for you. Personally I am not one that likes having to play catch up.....and i don't believe this stuff from certain ppl that the students can't handle the speed (with enough practice they should be fine)...btw did anyone see 25 in 2003 fly around, and 60/254 in 2004.....? "speed is king" imho....
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Unread 11-10-2004, 16:46
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Re: How slow is too slow?

Quote:
Originally Posted by Stephen Kowski
and i don't believe this stuff from certain ppl that the students can't handle the speed (with enough practice they should be fine)...btw did anyone see 25 in 2003 fly around, and 60/254 in 2004.....? "speed is king" imho....
If you were referring to my point, I wasn't saying that some people just cant drive fast. I'd hazard a guess that maybe 5% of all FIRST teams get a significant amount of practice time in before ship. The rest either havent finished their robots, or barely finished.

Once regionals roll around, the teams that practiced are going to do well and get more practice. The teams that didn't finish the bot are going to use the practice rounds to finish it, and maybe even some/most of the qualifying rounds. Those that finished the bot have time in the practice and qualifying rounds to learn to drive the bot.

So basically, for the average FIRST team, it takes AT LEAST one regional to become familiar with the robot, some maybe even two. Most teams attend one regional (and perhaps nationals) some attend two (nats, possibly) and hardly any attend 3 regionals (nats as a possibility again).

So unless you've had that practice time before build ends, or you have a second bot, or an old one that handles similarly, most teams dont have much practice at all coming into their first, or even second event, which makes having a very fast robot tough on the drivers.
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Unread 11-10-2004, 17:10
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Re: How slow is too slow?

Quote:
Originally Posted by Cory
If you were referring to my point, I wasn't saying that some people just cant drive fast.
No I wasn't....George1083 and I have had debates on this topic many times into the wee hours of the night/next morning....that is who I was referring to, and did not want to say his name, but I will if I need to clarify.

Despite what time you do or don't have I believe that working until the last minute is really quite pointless unless you have practiced what you are going to do on the field....otherwise ppl are just guessing what they think they can/can't do (but that is another debate altogether). Make time to practice for the drivers, otherwise all the engineering and work put into a robot is not wisely used if the product does not preform on the field.

Our new driver/drive team got experience and even though we didn't have such a stellar machine he/they drove well enough for us to be a part of the winning alliance in the Peachtree Regional. I don't mean to toot my team's proverbial horn, but that is the team I know best right now.

Ok im done.

Last edited by Stephen Kowski : 11-10-2004 at 17:17.
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Unread 11-10-2004, 22:33
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Re: How slow is too slow?

Quote:
Originally Posted by Stephen Kowski
No I wasn't....George1083 and I have had debates on this topic many times into the wee hours of the night/next morning.
I do think anything over 8 to 10 fps is too fast.

I formed this opinion after years of watching drivers do their thing. When machines went faster than about 10 fps, the drivers got very sloppy; they just weren't able to accomplish their tasks consistantly. Many times, they didn't use their top speed at all!

A slower top speed helps to keep your motors cool and gives you a bit more pushing force in addition to helping your drivers out.
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Unread 11-10-2004, 22:50
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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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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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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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Unread 11-10-2004, 23:39
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Re: How slow is too slow?

if there is sufficient practice among drivers, (usually by the time nationals rolls around..hehehe) a high top speed, if done within the limits of the team in question, done comfortably, the benefits are immense and immediately measurable. There was a direct happy finish for our team in Atlanta more than once due to our high gear.
Check out the final seconds of Match 53 at http://www.soap108.com/2004/movies/arc/index.cfm

where we streak across the field and prevent 1272 from capping.while that could have been done with 12 seconds left with a lower top speed, the fact is we spent another good 5 seconds manuvering with our grabbers, forcing the 2X ball to drop. Without that extra time, it is very likely that we wouldnt have succeeded. Thanks FEDS


Quote:
Originally Posted by George1083
I do think anything over 8 to 10 fps is too fast.

I formed this opinion after years of watching drivers do their thing. When machines went faster than about 10 fps, the drivers got very sloppy; they just weren't able to accomplish their tasks consistantly. Many times, they didn't use their top speed at all!

A slower top speed helps to keep your motors cool and gives you a bit more pushing force in addition to helping your drivers out.
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Last edited by J Flex 188 : 11-10-2004 at 23:43.
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Unread 12-10-2004, 10:51
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Re: How slow is too slow?

Quote:
Originally Posted by jonathan lall
George1083 is absolutely right (with regard to his last comment), but only in the case of single-speed gearboxes.
Quote:
Originally Posted by George1083
A slower top speed helps to keep your motors cool and gives you a bit more pushing force in addition to helping your drivers out.
In fact, this is totally a matter of gearing and the amount of throttle that your driver is using. If you've designed it right (suitable ratios), and are driving it right (full throttle as much as possible, pushing things as little as possible), the motors will be operating at a "happy" speed and temperature, no matter what your actual top speed is. Gearing it down (to increase torque) will not have any major effect on the operating temperature of the motors, unless the ratio was so unsuitable to begin with that you could hardly accelerate from a standing start--the driving conditions (mainly % throttle) are the primary concerns.


Quote:
Originally Posted by George1083
Many times, they didn't use their top speed at all!
This is the real sin. They won't save any battery life, and their motors will be operating out of their preferred range (contributing to excess heat, both because of the slow fan, and because of the higher current drawn due to lower voltage). This is also why it's nice to plan to change ratios, just in case your drivers don't like what they've got, and are unwilling (for strategic reasons) or unable (for human reaction time reasons) to alter their slow driving styles.
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Unread 12-10-2004, 11:10
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Re: How slow is too slow?

Not to change subject, but depending on how you read this hint we may be looking at a sprint start again...
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Unread 12-10-2004, 19:49
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Re: How slow is too slow?

9' PS!!! Man! thats a big wheel Dan.
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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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