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 I GET that FIRST is about more than winning on the field. BUT... ...it is my experience that the great programs of the FIRST world almost always build on a foundation of competitive robots. Success on the field begets success in other realms. - Joe Johnson [more] |
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This is the prototype we at Sparky 384 made using the 2 speed AndyMark Transmissions. The math said that it would go 45 MPH, but we only got it to around 35 MPH 
Discussion
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22-03-2005 14:35
Joe Matt
Re: pic: 35 MPH Prototype
James! You know 6.5 isn't street legal! Bad robot! Bad! Let's hope our resource officer dosn't find out abou this.... 
22-03-2005 14:50
sanddrag
Re: pic: 35 MPH Prototype
How did you measure/calculate/verify the actual speed. Also, it must have been kind of scary with that caster wheel huh? Also, what is the big tank for?
22-03-2005 14:56
BoyWithCape195
Re: pic: 35 MPH Prototype
Shifting without a compressor ?! (reason for tank maybe)
22-03-2005 14:57
Arefin Bari
Re: pic: 35 MPH Prototype
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Originally Posted by sanddrag
How did you measure/calculate/verify the actual speed. Also, it must have been kind of scary with that caster wheel huh? Also, what is the big tank for?
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What was the output ratio from transmission output to wheel?
22-03-2005 14:58
Crebb
Re: pic: 35 MPH Prototype
I calculated the theoretical top speed using the rpm and gear ratios in the transmissions. The big black tank is for the pneumatics to change gears. The tank is so big that we only filled it once for all the time we were playing with it. We didn't officially clock it at 35 MPH, but we were guestimating. And as for the caster in front, at the beginning it was centered. That thing bounced around so much I couldn't control it. But it was FUN!
The gear ratio in the transmission is 4.17:1 which is about 1247 rpm. Then it goes 1:1 from the transmission to the 12" wheel.
22-03-2005 15:28
Biff
Re: pic: 35 MPH Prototype
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Originally Posted by Crebb
I calculated the theoretical top speed using the rpm and gear ratios in the transmissions. The big black tank is for the pneumatics to change gears. The tank is so big that we only filled it once for all the time we were playing with it. We didn't officially clock it at 35 MPH, but we were guestimating. And as for the caster in front, at the beginning it was centered. That thing bounced around so much I couldn't control it. But it was FUN!
The gear ratio in the transmission is 4.17:1 which is about 1247 rpm. Then it goes 1:1 from the transmission to the 12" wheel. |
22-03-2005 15:43
Crebb
Re: pic: 35 MPH Prototype
The motor specs sheet I have been using has the CIM's going at 5200 rpm. That's what i've been basing my calculations on.
22-03-2005 15:46
Daniel Brim
Re: pic: 35 MPH Prototype
Whatever you do, don't show that design to Swampthing . Next thing you know, they'll come up with a robot that goes 40+ miles/hour reliably. As if their robot wasn't fast enough...
22-03-2005 15:47
Madison
Re: pic: 35 MPH Prototype
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Originally Posted by Crebb
The motor specs sheet I have been using has the CIM's going at 5200 rpm. That's what i've been basing my calculations on.
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If your robot were traveling 35 MPH, it'd be able to cross a football field in six seconds. Can it?
22-03-2005 15:48
some young guy
Re: pic: 35 MPH Prototype
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Originally Posted by BoyWithCape195
Shifting without a compressor ?! (reason for tank maybe)
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22-03-2005 16:16
Crebb
Re: pic: 35 MPH Prototype
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Originally Posted by M. Krass
That is approximately the CIM motors free speed. The motors are operating under load, so the actual output RPM is going to be something far lower than that. Additionally, if you're using the FIRST provided circuit breakers, the motors will draw more than 40A under load at a speed considerably lower than 5200 RPM, were they ever to go that fast.
If your robot were traveling 35 MPH, it'd be able to cross a football field in six seconds. Can it? |
I admit that it isn't practical and we wont use this setup on our robot next year (most likely), but it sure is fun.
22-03-2005 17:30
tkwetzel
Re: pic: 35 MPH Prototype
Is it FIRST legal? I am assuming not because of the air tank you used.
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Originally Posted by some young guy
o man i thought the black tank was for the Nirtous Oxide...darnet that would have been cool
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.
22-03-2005 17:34
KTorak
Re: pic: 35 MPH Prototype
This looks like something I would want to do in the summer in my free time. Yay for using math calculations to figure out speed We used the long equations mentioned so we could gear our robot for ~12-15 Ft/S this season 
But heck, 35 MPH is insane.
22-03-2005 17:38
Conor Ryan
Re: pic: 35 MPH Prototype
try a bigger battery, like 24 volts. That may change some stuff. Also you may want to impliment a cooling system if you haven't already.
22-03-2005 18:30
sirbleedsalot
Re: pic: 35 MPH Prototype
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Originally Posted by tkwetzel
Is it FIRST legal? I am assuming not because of the air tank you used.
Electric motors....nitrous oxide? They would get more power out of putting NOS stickers on their bot than actually putting a nitrous tank on it. Because all the NOS tank would do would be weigh down the bot . |
Hey some of our team members decided it would be funny to put NOS stickers on our robot, so we have NOS.
22-03-2005 19:12
Mr. Ivey
Re: pic: 35 MPH Prototype
Really James, don't let the resource officer find out about that,the speed limit on that road is 25 mph. You could get a ticket. Just think if you were given a speeding ticket for breaking the speed limit with a robot!
22-03-2005 20:17
NoodleKnight
Re: pic: 35 MPH Prototype
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Originally Posted by tkwetzel
Electric motors....nitrous oxide? They would get more power out of putting NOS stickers on their bot than actually putting a nitrous tank on it. Because all the NOS tank would do would be weigh down the bot
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Or use it to fuel a rocket engine! Just a matter of heating the stuff right.
22-03-2005 20:34
elknise
Re: pic: 35 MPH Prototype
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Originally Posted by NoodleKnight
Or they could just open a large dump valve to spray the nitrous backwards, kinda like using a fire extinguisher to create propulsion, I mean, with a full tank, it'll be some high compression there.
Or use it to fuel a rocket engine! Just a matter of heating the stuff right. |
22-03-2005 20:40
tkwetzel
Re: pic: 35 MPH Prototype
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Originally Posted by cdr1122334455
try a bigger battery, like 24 volts. That may change some stuff. Also you may want to impliment a cooling system if you haven't already.
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22-03-2005 22:25
henryBsick
Re: pic: 35 MPH Prototype
Its cool and all..... but when I see a robot: tipping the scales at over 130 lb,with battery and all; using only two CIM motors/side and no liquid nitrogen or any other cooling implement that can turn the motors into superconductors; and still do 35 miles an hour while using 40 amp breakers. WOW that is the day I shave my head.
But aside form that is it shiggidy shweet to say "I have a 35 mph robot!"
22-03-2005 22:31
KTorak
Re: pic: 35 MPH Prototype
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Originally Posted by elknise
That would be cool, a 35mph bomb/rocket
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22-03-2005 22:52
Joe Menassa
Re: pic: 35 MPH Prototype
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Originally Posted by Crebb
We did have trouble tripping the breakers. The first time we tried it out we only had one CIM per gearbox, but we added two more. The road we tested on had a slight hill, so if we started off in first gear and shifted into second it did fine. As for the football field in 6 seconds, it would be close. I need to find a radar gun somewhere.
I admit that it isn't practical and we wont use this setup on our robot next year (most likely), but it sure is fun. |
Radar gun? Does anyone have a license? Just drive along side it in a car! JK! (-NOT SAFE-)
Back in high school a few friends and I attempted something similar with very minimal success.
Good job.
22-03-2005 22:52
NoodleKnight
Re: pic: 35 MPH Prototype
I was wondering, how controllable is it at high speeds? How do you keep it driving straight, or do you just drive this in an open area? And most importantly, how fast does it accelerate from 0-35mph?
22-03-2005 23:00
sanddrag
Re: pic: 35 MPH Prototype
I have a Mabuchi RS 750SH motor (bigger than the FP but still maybe 1/2 size of CIM) sitting on my desk that I pulled out of an old Makita Drill. I was thinking I'd either build an RC car around it or put it in a car I have. How do you think I should gear that in a ~9lb car? How fast could I get it to go do you think?
23-03-2005 05:58
Adam Krajewski
Re: pic: 35 MPH Prototype
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Originally Posted by tkwetzel
Is it FIRST legal? I am assuming not because of the air tank you used.
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23-03-2005 07:14
Crebb
Re: pic: 35 MPH Prototype
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Originally Posted by NoodleKnight
I was wondering, how controllable is it at high speeds? How do you keep it driving straight, or do you just drive this in an open area? And most importantly, how fast does it accelerate from 0-35mph?
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We like to use that big pneumatics tank on prototypes because it lasts so long. It was just sitting around in the shop, so I wouldn't be suprised if it was from 2000.
23-03-2005 09:12
Jeff Waegelin
Re: pic: 35 MPH Prototype
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Originally Posted by Adam Krajewski
That tank looks familiar... I believe it was actually in the kit of parts way back in 2000.
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23-03-2005 12:35
Anthony Kesich
Re: pic: 35 MPH Prototype
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Originally Posted by tkwetzel
Electric motors....nitrous oxide? They would get more power out of putting NOS stickers on their bot than actually putting a nitrous tank on it. Because all the NOS tank would do would be weigh down the bot
. |
30-03-2005 17:19
some young guy
Re: pic: 35 MPH Prototype
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Originally Posted by NoodleKnight
Originally Posted by tkwetzel
Electric motors....nitrous oxide? They would get more power out of putting NOS stickers on their bot than actually putting a nitrous tank on it. Because all the NOS tank would do would be weigh down the bot .Or they could just open a large dump valve to spray the nitrous backwards, kinda like using a fire extinguisher to create propulsion, I mean, with a full tank, it'll be some high compression there. Or use it to fuel a rocket engine! Just a matter of heating the stuff right. |
31-03-2005 13:00
ConKbot of Doom
Re: pic: 35 MPH Prototype
In 2004 for some reason someone thought 4:1 would be a good ratio to gear down the CIMs to the 12" skyway wheels. The bot moved all right, but it sounded angry. ugh... that thing was hard enough to control with a 13:1 gear down, I would have hated to try to drive it at 4:1... 2 side wheels, and a castor at each corner...
Very nice to see something as just proof of concept.
31-03-2005 16:02
Frank(Aflak)
Re: pic: 35 MPH Prototype
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Originally Posted by M. Krass
That is approximately the CIM motors free speed. The motors are operating under load, so the actual output RPM is going to be something far lower than that. Additionally, if you're using the FIRST provided circuit breakers, the motors will draw more than 40A under load at a speed considerably lower than 5200 RPM, were they ever to go that fast.
If your robot were traveling 35 MPH, it'd be able to cross a football field in six seconds. Can it? |
it'll just take a while to get there, but the only resistive forces it would need to overcome would be innefficiency in the gearbox and wind resistance.
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