Robot Speeds - Opinions sought

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Posted by Thomas A. Frank.

Engineer on team #121, The Islanders/Rhode Warrior, from Middletown (RI) High School and Naval Undersea Warfare Center.

Posted on 2/7/2000 9:16 AM MST



Hello All;

I'm assuming that most of you have a running chassis by now.

When we started out this year, we theorized that the vast
majority of teams would fall into the 4-6 feet per second
range, or about 8-12 seconds to cross the field, and designed
accordingly.

Did we guess correctly?

Tom Frank

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Posted by Joe Johnson.   [PICTURE: SAME | NEW | HELP]


Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

Posted on 2/7/2000 1:17 PM MST


In Reply to: Robot Speeds - Opinions sought posted by Thomas A. Frank on 2/7/2000 9:16 AM MST:



4-6 feet per second...

hmm...

okay, with an 8 inch wheel thats about 2-3 rev per second or 120-180 RPM

The Drill motors has a free speed of about 20,000 RPM so...

From Drill motor to 8 inch wheel we'd be talking about a 170-110 to 1 ratio.

I suppose that is about right.

With the transmission in low that would mean about a 2 or 3 to 1 ration from the output of the drill trans to the wheel.

Every year I tell a bunch of rookie teams that your robot shouldn't be able to out-run you, but it should probably be able to make you walk kind of fast. Somewhere in between is the right ratio.

The 4-6 ft per second falls into that range.

What ratio will Chief Delphi V have? Not ready to commit yet ;-)

Joe J.

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Posted by Tom Wible.   [PICTURE: SAME | NEW | HELP]


Coach on team #131, chaos, from central high school manchester and osram-sylvania.

Posted on 2/7/2000 3:50 PM MST


In Reply to: guessing on ratios posted by Joe Johnson on 2/7/2000 1:17 PM MST:



Our robot is going be fast, and powerful too. Faster than anything you've mentioned so far. (without shifting the drill trannys) How you ask? Not tellin' !

Tom Wible
Team #131

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Posted by Dodd Stacy.

Engineer on team #95, Lebanon Robotics Team, from Lebanon High School and CRREL/CREARE.

Posted on 2/7/2000 4:16 PM MST


In Reply to: Re: guessing on ratios posted by Tom Wible on 2/7/2000 3:50 PM MST:



We've set up to change our main drive wheel gear ratio fairly easily, a la bicycle derailleur (?) - 2 variable ratios in series. Top speed depends only on what we find our drivers are able to control, for all practical purposes. A second pair of motors, direct drive at relatively low ratio to a second pair of wheels through over running clutches, provides traction-limited acceleration off the line, for when the main drive is geared tall. We're looking forward to interesting drag races for the balls at the far end.

Dodd

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Posted by Joe Johnson.   [PICTURE: SAME | NEW | HELP]


Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

Posted on 2/7/2000 5:04 PM MST


In Reply to: Ditto posted by Dodd Stacy on 2/7/2000 4:16 PM MST:



Dodd,

I have long been in awe of the machines out of Lebanon Robotics!

From the amazing ball extruder you had in Ladder Logic to the Omni Directional Goal Emptier you had at the Rumble last year, you never fail to impress me.

I am sure that this year will be no different.

As to the over-running cluthes, do they work in reverse as well? What happens to your machine if you try to back up? I would think that the slower motors may make you kind of creepy in reverse.

Am I missing something?

Joe J.

P.S. Perhaps you should write a book about all the clever mechanism you have put on your machines over the years. It would be a thick volume as well as a best seller (at least in the FIRST community). Think about it.

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Posted by Lora Knepper.

Student on team #69, HYPER (Helping Youth Pursue Engineering & Robotics), from Quincy Public Schools and The Gillette Company.

Posted on 2/7/2000 7:28 PM MST


In Reply to: Leave it to Lebanon posted by Joe Johnson on 2/7/2000 5:04 PM MST:



I'm with Joe 100% on this one! Every machine produced by your team had never failed to amaze me. I remember the first time we realized that our doublers were disapearing in 1998! Talk about shock! And you saved us last year at Rumble. I look forward to yet another ingenious machine from you guys!

Lora

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Posted by Andy Grady.   [PICTURE: SAME | NEW | HELP]


Coach on team #42, P.A.R.T.S, from Alvirne High School and Daniel Webster College.

Posted on 2/7/2000 10:37 PM MST


In Reply to: Re: Leave it to Lebanon posted by Lora Knepper on 2/7/2000 7:28 PM MST:



Definately alot of credit to Lebanon, I don't know what was more impressive, their unbelievable multi directional drive system, or the even more unbelievable puck tipping mechanism. One of the matches that stuck out most in my mind was when lebanon was tiping the puck at an angle that looked to be nearing 45 degrees on Assabet at River Rage last year. They were definately among my top 10 favorite teams to watch last year, i can't wait to see what tricks they have up their sleeves this year.
Good Luck all,
Andy Grady, DWC/Alvirne

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Posted by Dodd Stacy.

Engineer on team #95, Lebanon Robotics Team, from Lebanon High School and CRREL/CREARE.

Posted on 2/8/2000 8:45 AM MST


In Reply to: Leave it to Lebanon posted by Joe Johnson on 2/7/2000 5:04 PM MST:




: As to the over-running cluthes, do they work in reverse as well? What happens to your machine if you try to back up? I would think that the slower motors may make you kind of creepy in reverse.

: Am I missing something?

: Joe J.

As usual, Dr. Joe misses nothing, sees right through the smoke screen. I guess it was the clutches that tipped you off. OK, I'll come clean - it's actually a retrohyperdrive for achieving warp speeds in reverse. We rewound the low speed (Globe) motors with HTS wire and immerse them in liquid nitrogen. Then when the high speed main (drill) motors overdrive the Globes in reverse, through those pesky clutches, the Globes become superconducting generators. We couple the Globe output back to the drill inputs through multiple #6 wire direct shunts, and the whole thing just goes faster and faster till our watches slow down and everybody starts talking slow with real deep voices. One of the kids dreamed it up after my lecture about perpetual motion machines.

Actually, this year we're 'just' trying for a modest offensive competance, something we haven't given enough attention in past years, in our shameless efforts to entertain. I admire every team that shows up with a rolling robot, and I really respect the teams and machines that consistently and reliably play the game well and quickly and put the numbers on the board. And then, one (or two, or three) of them are the champs. Sounds so simple. Is so hard.

Good luck, everybody.

Dodd

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Posted by Andy Baker.

Engineer on team #45, TechnoKats, from Kokomo High School and Delphi Automotive Systems.

Posted on 2/8/2000 7:21 AM MST


In Reply to: Ditto posted by Dodd Stacy on 2/7/2000 4:16 PM MST:



That will be the trick this year: the ability to change to a lower gear on the fly. Kudos to you and your team, Dodd!

We were trying to go with a CVT (continuously variable transmission)... but without success. We bailed on the CVT due to some many losses in the system. It works, but there is too much friction and some binding between the toroidal plates.

What this CVT would've done is have constant acceleration... we figured that it could've run into the far wall (48 feet away) at 20 mph.

We'll have the contraption in our pits at the competition... please come by and take a look, 'cause you'll probably see it on our 'bot in 2001 (depending on field size).

Andy B.

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Posted by Dodd Stacy.

Engineer on team #95, Lebanon Robotics Team, from Lebanon High School and CRREL/CREARE.

Posted on 2/8/2000 9:02 AM MST


In Reply to: Way to Go! No CVT for us :( posted by Andy Baker on 2/8/2000 7:21 AM MST:



: That will be the trick this year: the ability to change to a lower gear on the fly. Kudos to you and your team, Dodd!

Andy, sorry I must have overstated. We can't shift on the fly. It's the old fashioned way, changing sprockets in the pits. With the drill gearbox (which we prefer to run in high) in series with a chain and sprocket pair, we chose two different driving sprocket sizes that give a reasonable spread of the 4 ratio steps between low-low and high-high. We just decided to make that easy to do for once. It's only 'quick change' compared to drifting and driving pins. I'm assuming we'll settle on an overall ratio during test/practise/break/fix 'week' and leave it there.

Dodd

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Posted by Thomas A. Frank.

Engineer on team #121, The Islanders/Rhode Warrior, from Middletown (RI) High School and Naval Undersea Warfare Center.

Posted on 2/8/2000 10:02 AM MST


In Reply to: Way to Go! No CVT for us :( posted by Andy Baker on 2/8/2000 7:21 AM MST:



: We were trying to go with a CVT (continuously variable transmission)... but without success. We bailed on the CVT due to some many losses in the system. It works, but there is too much friction and some binding between the toroidal plates.
---------------
Dear Dodd;

I find the fact that you folks built a prototype and had it working is amazing in itself! I anxiously look forward to seeing it.

We thought about such things for a few brief moments, and realized that it was well beyond our ability to construct in the time available, and went for conventional.

That teams are even considering such things, much less building them and trying them out, is what brings me back to FIRST year after year. It's sort of like being inside a living version of Popular Science from the 50's and 60's...FIRST demonstrates quite clearly the amazing things that can happen when the creative talents of engineering community are unleashed.

Tom Frank

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Posted by Thomas A. Frank.

Engineer on team #121, The Islanders/Rhode Warrior, from Middletown (RI) High School and Naval Undersea Warfare Center.

Posted on 2/8/2000 10:06 AM MST


In Reply to: Re: Way to Go! No CVT for us :( posted by Thomas A. Frank on 2/8/2000 10:02 AM MST:



Dear Dodd;

Meant Dear Andy...

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Posted by Andy Baker.

Engineer on team #45, TechnoKats, from Kokomo High School and Delphi Automotive Systems.

Posted on 2/8/2000 9:24 PM MST


In Reply to: Re: Way to Go! No CVT for us :( posted by Thomas A. Frank on 2/8/2000 10:02 AM MST:



Tom,

We'll have it at the competitions (MI, IL, Epcot), but it's designer will not be able to make it. Our multi-talented ME/EE Mark Koors will be in Haiti on missionary work during our Regionals and on a family vacation during Nationals.
BUT, I'll be taking notes about what all of you think of this contraption and how to make it better.

Andy B.

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Posted by Jon.

Engineer on team #190, Gompei, from Mass Academy of Math and Science and Worcester Polytechnic Institute.

Posted on 2/8/2000 8:17 AM MST


In Reply to: Ditto posted by Dodd Stacy on 2/7/2000 4:16 PM MST:



We're building a DualSpeed system as well, but all i can say is that we will not be using a deraileur design... :)
all other details are classified... for now...
New Jersey, Hartford, then the World!

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Posted by Nate Smith.

Other on team #66, GM Powertrain/Willow Run HS, from Eastern Michigan University and GM Powertrain.

Posted on 2/8/2000 8:34 AM MST


In Reply to: Ditto posted by Dodd Stacy on 2/7/2000 4:16 PM MST:



Hmmm, seems like a lot of people are going for two(or more) speed drive trains right now...unfortunately, that's all I can say at this time...

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Posted by Greg Mills.

Engineer on team #16, Baxter Bomb Squad, from Mountain Home and Baxter Healthcare.

Posted on 2/8/2000 10:29 AM MST


In Reply to: The Year of the Shifter posted by Nate Smith on 2/8/2000 8:34 AM MST:



:
A strange world - we have been shifting since '96 and have always had a high & low - until this year. We are going the other way - back toward a robust, reliable, single speed system. Not super fast - a little over 8fpm - but highly controllable and alot of powered wheels on the floor.

That is what is great about going to the competitions - seeing what everybody else thinks is the best way.

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Posted by Greg Mills.

Engineer on team #16, Baxter Bomb Squad, from Mountain Home and Baxter Healthcare.

Posted on 2/8/2000 11:45 AM MST


In Reply to: Re: The Year of the Shifter posted by Greg Mills on 2/8/2000 10:29 AM MST:



: :
: OK - OK try 8 fps - I was off by a factor of 60

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Posted by Joe Johnson.   [PICTURE: SAME | NEW | HELP]


Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

Posted on 2/8/2000 2:06 PM MST


In Reply to: Re: The Year of the Shifter posted by Greg Mills on 2/8/2000 11:45 AM MST:



I don't know what you folks are thinking but if what I read here is any indication, a lot of you are heading for a world of hurt (imho -- Greg Mills, Baxter Mountain Home, and other bastions of sanity excluded as usual).

If you are talking about gear ratio where you realistically expect to reach 20mph I think you're crazy.

Shifting is tricky business, not for the faint of heart.

20 mph is way to fast to actually control unless you are in a parking lot somewhere (again imho).

Also, do you realize what rpm an 8 inch wheel has to spin at to go 20MPH? 840rpm!!!!

We are talking about a 25:1 ratio from the armature of the drill motor to an 8 inch wheel!!!

If any team uses such a low ratio, I predict that either the Victors or the Motors or both will literally catch fire at some point during the competion.

(Teams bold enough to shift on the fly are free to tell me that they told me so, but I don't expect a lot of teams to actually be able to carry this off effectively).

Shut my mouth at the Nationals.... Until then, I will remain skeptical about 20 mph robots.

Joe J.

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Posted by Kevin Sevcik.

Other on team #57, Tigers, from BT Washington and the High School for Engineering Professions and Exxon, Kellog Brown & Root, Powell Electrical.

Posted on 2/8/2000 2:33 PM MST


In Reply to: Try this: Year of the Flaming Victor (or Motor) posted by Joe Johnson on 2/8/2000 2:06 PM MST:



Actually, I think it'd be interesting to see a robot going 20 mph. I mean, imagine what would happen if they had to go over the ramp at that speed. :^) I think a robot goind at that speed is either going to have to be a limbo bot, or really robust and well balanced.

Kevin Sevcik

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Posted by Thomas A. Frank.

Engineer on team #121, The Islanders/Rhode Warrior, from Middletown (RI) High School and Naval Undersea Warfare Center.

Posted on 2/9/2000 9:25 AM MST


In Reply to: Try this: Year of the Flaming Victor (or Motor) posted by Joe Johnson on 2/8/2000 2:06 PM MST:



: If you are talking about gear ratio where you realistically expect to reach 20mph I think you're crazy.


Thank you Joe, for confirming my engineering opinion/overall suspicion. If anyone succesfully breaks the 10 fps avg velocity barrier (on the field, over the 48 feet, at full match weight), I'll be very impressed (amazed might be a better word) indeed.

In fact, if any team achieves 12 fps average for the full field length (4 seconds wall to wall, full match weight, we'll let FIRST be the judge), I'll personally bring that team a case of soda (aka pop for you mid-westerners; their choice of brand) the following day!

Tom Frank

P.S. - I'd say the motors will ignite before the Victor's...

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Posted by Dodd Stacy.

Engineer on team #95, Lebanon Robotics Team, from Lebanon High School and CRREL/CREARE.

Posted on 2/9/2000 9:31 PM MST


In Reply to: Try this: Year of the Flaming Victor (or Motor) posted by Joe Johnson on 2/8/2000 2:06 PM MST:



I hate to be a wet blanket on the 20 mph robot business, but let's put some numbers on that. A 130 lb robot traveling 20 mph possesses a kinetic energy in excess of 2,000 Joules (sorry about the mixed units, but this is America). I believe Joe has cast the drill motors as about 250 watts (J/sec) of max power output each. Postulate lossless CVT transmissions that allow the two drill motors to run always at their peak power rpm as the robot accelerates from rest to 20 mph. We need 4 seconds for 500 watts worth of motor to increase the kinetic energy of the robot by 2,000 Joules, to accelerate from rest to 20 mph.

Anyone care to calculate whether the robot will achieve the 20 mph velocity before hitting the end wall?

Dodd

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Posted by Dodd Stacy.

Engineer on team #95, Lebanon Robotics Team, from Lebanon High School and CRREL/CREARE.

Posted on 2/10/2000 10:05 AM MST


In Reply to: Reality Check posted by Dodd Stacy on 2/9/2000 9:31 PM MST:




: Anyone care to calculate whether the robot will achieve the 20 mph velocity before hitting the end wall?

OK, time's up. Our highly idealized 130 lb dragbot with 500 w lossless CVT drive hits the end wall at just under 15 mph about 2.6 seconds after the start. There's a brief period of wheelspin (0.05 sec) at the start, during which the bot travels 0.03 ft and gets up to 1.9 mph before hooking up for the rest of the sprint. So don't bet your pink slip on a 20 mph trap speed.

I will buy a case of cola (or?) for any team whose bot can touch the balls at the far end of the field within 4 seconds after it moves from the starting position. (And I'll help scrape the bot off the end wall, too.)

I'll also wager no bot will clear the downslope of the ramp in the air, ie; land on the floor - not the ramp - after crossing the peak of the ramp. The gauntlet's down!

Dodd

(Disclaimer: Professional drivers shown on closed course. Do not attempt with your bot.)

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Posted by Joe Ross.   [PICTURE: SAME | NEW | HELP]


Coach on team #330, Beach Bot 2000, from Hope Chapel Academy and NASA/JPL & J&F Machine.

Posted on 2/10/2000 2:35 PM MST


In Reply to: SPLAT! posted by Dodd Stacy on 2/10/2000 10:05 AM MST:



Before we changed our gear ratios, we timed 3.8 seconds from starting position until we were stopped at the other end, for our 120 lb robot

We don't have new times yet and we didn't try to go over the ramp.

FYI no drill motors were harmed!

Joe Ross
Team 330


: I will buy a case of cola (or?) for any team whose bot can touch the balls at the far end of the field within 4 seconds after it moves from the starting position. (And I'll help scrape the bot off the end wall, too.)

: I'll also wager no bot will clear the downslope of the ramp in the air, ie; land on the floor - not the ramp - after crossing the peak of the ramp. The gauntlet's down!

: Dodd

: (Disclaimer: Professional drivers shown on closed course. Do not attempt with your bot.)

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Posted by Thomas A. Frank.

Engineer on team #121, The Islanders/Rhode Warrior, from Middletown (RI) High School and Naval Undersea Warfare Center.

Posted on 2/23/2000 3:31 PM MST


In Reply to: SPLAT! posted by Dodd Stacy on 2/10/2000 10:05 AM MST:




: I will buy a case of cola (or?) for any team whose bot can touch the balls at the far end of the field within 4 seconds after it moves from the starting position. (And I'll help scrape the bot off the end wall, too.)

: I'll also wager no bot will clear the downslope of the ramp in the air, ie; land on the floor - not the ramp - after crossing the peak of the ramp. The gauntlet's down!

Hi Dodd;

I made the same wager (on the four seconds). I expect to have to pay off.

You see, our machine achieved both of the criteria you set forth above. Unfortunately, the power needed was so high that it had really bad effects on the drivetrain (I'll bring some of the stripped gears with me), battery (life expectancy was very low), and main fuse (it was getting HOT), and the drivers found it almost uncontrollable, so we detuned it to a much more reasonable level.

Now what we lack in speed we more than make up for in pushing power :-)

I miss the flying...

Tom Frank

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Posted by Dodd Stacy.

Engineer on team #95, Lebanon Robotics Team, from Lebanon High School and CRREL/CREARE.

Posted on 2/23/2000 6:14 PM MST


In Reply to: Re: SPLAT! posted by Thomas A. Frank on 2/23/2000 3:31 PM MST:




: Hi Dodd;

: I made the same wager (on the four seconds). I expect to have to pay off.

: You see, our machine achieved both of the criteria you set forth above. Unfortunately, the power needed was so high that it had really bad effects on the drivetrain (I'll bring some of the stripped gears with me), battery (life expectancy was very low), and main fuse (it was getting HOT), and the drivers found it almost uncontrollable, so we detuned it to a much more reasonable level.

: I miss the flying...

: Tom Frank

Tom,

You guys did it, you win the bet. Name your sugar water. We'll settle at Rutgers or in Orlando, wherever we see the fabulous (ex) flying Rhode Warrior 2000 first. Bravo Zulu!

Dodd

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Posted by Tom Wible.   [PICTURE: SAME | NEW | HELP]


Coach on team #131, chaos, from central high school manchester and osram-sylvania.

Posted on 2/9/2000 7:14 PM MST


In Reply to: Re: guessing on ratios posted by Tom Wible on 2/7/2000 3:50 PM MST:



We will be having a two speed robot, without shifting anything! The low speed will be for pushing, and the high speed for getting around town. I can't wait to see it hit the ramp in Hartford!

Tom Wible
Team C.H.A.O.S.

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Posted by Andy Baker.

Engineer on team #45, TechnoKats, from Kokomo High School and Delphi Automotive Systems.

Posted on 2/8/2000 7:12 AM MST


In Reply to: Robot Speeds - Opinions sought posted by Thomas A. Frank on 2/7/2000 9:16 AM MST:



Tom,

I think that you're guessing too low. I think that there will be some teams at 15 fps (10 mph) and the majority at 6-8 fps.

Reminder to all teams: don't even think about running your drive base around without weighing it down to the maximum weight of 130 lbs. Get some boxes of screws or something and send them for a ride on your drive base. You will find out very soon if the carpet is your friend or enemy.

Use plenty of duct tape... those boxes will want to fall off!

Good luck,
Andy B.

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Posted by Lora Knepper.

Student on team #69, HYPER (Helping Youth Pursue Engineering & Robotics), from Quincy Public Schools and The Gillette Company.

Posted on 2/8/2000 4:14 PM MST


In Reply to: Remember to WEIGH IT DOWN posted by Andy Baker on 2/8/2000 7:12 AM MST:



I second that from experience. Not only does it show how you affect the carpet, but it also gives you a pretty good idea on how your 'bot will handle. From just driving a proto base, to a fully loaded robot, nothing usually handles more differently. This is especially essential if your drivers won't have a lot of practice time.

Lora

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Posted by Nate Smith.

Other on team #66, GM Powertrain/Willow Run HS, from Eastern Michigan University and GM Powertrain.

Posted on 2/10/2000 12:51 PM MST


In Reply to: Re: Remember to WEIGH IT DOWN posted by Lora Knepper on 2/8/2000 4:14 PM MST:



Speaking from experience...if you're going to add weight to your machine, make sure to put it where it can be anchored securely. Also, try not to have any of the weight outside the footprint of your machine...if you hit something with your extra weight and it shifts that weight, who knows what it's going to hit?

Nate

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Posted by Ken Patton.   [PICTURE: SAME | NEW | HELP]


Engineer on team #65, The Huskie Brigade, from Pontiac Northern High School and GM Powertrain.

Posted on 2/8/2000 10:13 AM MST


In Reply to: Robot Speeds - Opinions sought posted by Thomas A. Frank on 2/7/2000 9:16 AM MST:



I think there will be a lot of teams going faster than that. We are planning to be pretty fast for the initial drag race across the field.

Ken

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Posted by Daniel.

Coach on team #483, BORG, from Berkeley High School and NASA Ames & UC Berkeley.

Posted on 2/8/2000 12:10 PM MST


In Reply to: faster, I think posted by Ken Patton on 2/8/2000 10:13 AM MST:



What's all this talk about drag races? Oh wait! I get it! You guys are going for the balls.....

;-)

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Posted by Raul.

Engineer on team #111, Wildstang, from Rolling Meadows & Wheeling HS and Motorola.

Posted on 2/8/2000 4:59 PM MST


In Reply to: faster, I think posted by Ken Patton on 2/8/2000 10:13 AM MST:



With all the drag racing to the wall going on,the teams that stay back may get a large share of the balls. If a couple of bots crash into the balls, they will just spread all over the place and some will end up back on the other side of the goal.

This is a viable strategy for a team who has an alliance partner that cannot get across the goal/ramp effectively. They can just sit back, collect the stray balls then get the rest from the human player. In the meantime, the other robot can continue to harass the other two robots on that side and maybe even pick up a few balls.

Raul