What teams have desgined a 6 wheel drive system?
 

also, what teams have used it during the season as a competition bot?

I've tried searches but there is a lot and would be easier and easily updated with the thread asking for what teams that designed and built a 6 wheel drive system.

thanks

pb

Re: What teams have desgined a 6 wheel drive system?
 

we did a 6-wheel direct gear drive train in 2004; what is it specifically that you're trying to find out?

Re: What teams have desgined a 6 wheel drive system?
 

419 did it in 2001. 47, 25, 22, 254/60 and others have done it in the past 2 years.

Re: What teams have desgined a 6 wheel drive system?
 

This year, or ever?

This year, off the top of my head:

254
60
22
25
47
980
168
233
360
I want to say 27 and 599 also, but I'm not 100% sure

you can find pictures of all of these at www.firstrobotics.net, and Im sure you can find some others in their galleries also

Re: What teams have desgined a 6 wheel drive system?
 

Yeah we did a 6-wheel drive system for the past 2 years. I find it is that those drive sytems are the most versitile, with or without a gearbox.

Re: What teams have desgined a 6 wheel drive system?
 

I know my team built a 6-wheel drive in 2002, but this was before my time and I don't know too much about it. The only pictures I could find on CD were here and here, but they probably won't help too much.
_Alex

Re: What teams have desgined a 6 wheel drive system?
 

We did a 6 wheel prototype last fall. We kind of parted it out though... but we still have the chassis and wheels on it.

-Kyle

Re: What teams have desgined a 6 wheel drive system?
 

wow, i wasn't expecting all this information!

thanks, is there any pictures of thier drive systems of any of the drive systems?

or possibly inventor files.. thanks!

Re: What teams have desgined a 6 wheel drive system?
 

I think we are on our third year of 6 wheel drive. Scorpion in 02 had 6, well im pretty sure it did, and this years and last years had 6, with just minor adjustments. If you want pm me to remind me to look for some pics or files. Im sure i have something, just where is the problem. And if you ever come to a competition with us there, we bring a spare drive train to show to judges and whomever wants to see it better.

Re: What teams have desgined a 6 wheel drive system?
 

I know you said 6, but... Team 75 had an 8-wheel drive system last year. It was terrific for getting up steps. You can PM me for more info if you want.

Re: What teams have desgined a 6 wheel drive system?
 

I think my team has a lot of 6 wheel drive experiance. We have build 1 practice robot with 6 wheels with the middle 2 lower to the ground which allows us to turn but still be stable. We used the 6 inch pneumatic wheels from the 03-04 competition kit (i think). We also used drill motors in custom built gear box (only made w/ drill press, no milling or cnc machienes). Then we went to a rather complex chain system that connected all 6 wheels to the motor. I believe we had a top speed of 8 ft/s.

Here is that bot, the so called NoodleBot since we attached pool noodles so we didnt hurt the walls:

http://nemesis2.com/phs/robotics/gal...logged=&inc=15

Here are some movies as well:

http://www.plainedgeschools.org/hsro...otinaction.wmv
http://www.plainedgeschools.org/hsro...eo/cartweb.wmv
http://www.plainedgeschools.org/hsro...battlebots.wmv

Although 6 wheels has many benefits of a 6 wheel bot, IMO there are also many setbacks that you will come across. Here are the problems we had with noodlebot and why we could not use that drive train design in the competition last year. It was so low to the ground that there was no way with those wheels we were getting over the step. A bigger problem is that it is extreamly difficult to get a 6 wheel bot with the teetering middle 2 wheels to go strait. A gyro or some other method of keeping it strait is really needed to accurate manuvering. There are also a lot of weight issue, noodlebot was 70pnds without anything else on it.

Right now we are in the middle of building a 6 wheeled robot that can go up the step and uses the 12 inch pneumatic wheels. We also shaved a lot of weight off the drivetrain by using a lot less chains then we used in noddle bot. We now only have 4 chains for the drivetrain instead of 8 and use all but 2 little sprockets. Right now its at 42 pounds. Once we get it moving and take some pictures of it I will show them to you.

If you are interested in more details just PM me and I would be glad to share. :]

Re: What teams have desgined a 6 wheel drive system?
 

We (862) have not had one for competition but this past summer we designed one to use for sensor testing but have yet to finish building it.

Re: What teams have desgined a 6 wheel drive system?
 

6 Wheels are the only way to go!! We used the 12" wheels on the outside and 6" center wheels to pivot on.

Team 701 6-wheels

8 Wheels are nice too!!

8-Wheeled Bot

And the coolest 6-Wheeled bot ....

The Best 6-Wheeler

Re: What teams have desgined a 6 wheel drive system?
 

thanks for all the support!

Re: What teams have desgined a 6 wheel drive system?
 

Team 492 has made at least one six-wheel drive robot for the FIRST competition.

Re: What teams have desgined a 6 wheel drive system?
 

I'm not sure if Team 25 has Inventor files, but they graciously shared their 2003 Evil Machine design with Team 103 who used it on their 2004 bot Monkey Business. Team 103 used only four wheels, but adding the additional two is no problem at all (In fact 103 had two more wheels on just two weeks before shipping). The Team 103 version of the Team 25 drive system is well documented in the 2004 Inventor Website found here:
http://inventor.cybersonics.org

Re: What teams have desgined a 6 wheel drive system?
 

6 wheels are awesome.... i would use them on ANY robot even 6" wheels and definitely 6 wheels are necessary for anything over 8" / pneumatic otherwise turning sucks.... the main thing is that the center wheel MUST be lower than the other two wheels otherwise its pretty pointless.... i guess you get more traction (and less turning) but with the center wheel our robot w/ 12" pneumatic tires, turned about 20 times better than our 2003 bot which had 4 wheels and 8" rubber tires :ahh:

Re: What teams have desgined a 6 wheel drive system?
 

Team 356 has used a six wheeled drive system (with suspension) in 2003 and in 2004. In 2003 we had chips and drills driving separate wheels (with the front wheels being chain driven from the center wheels powered by the drills). In 2004, all six wheels were independently driven (chips, drills, fps).

In 2003, the front suspension helped us keep all six wheels on the ramp and top of the platform when we were attempting to take the hill.

In 2004, the suspension helped us climb onto the two platforms. We generally had 4-6 wheels in contact with a surface at all times.

2003, the Velvet Fog (http://www.chiefdelphi.com/forums/sh...light=team+356)
(http://www.chiefdelphi.com/forums/sh...threadid=17799)

2004, Wolfgang (http://www.chiefdelphi.com/forums/sh...ad.php?t=25833)

Re: What teams have desgined a 6 wheel drive system?
 

Team 980 learned about the 6-wheel drive system (with middle wheels 3/16" lower) from Team 254 and Team 60. They in turn credited Team 25 with the idea.

This idea was a breakthrough for us. Previously we had to keep gearing down our robot so that we could turn without blowing fuses (especially turning in place). This last season, using 6 wheels, our robot could spin like a top. We used programming to implement a reduced turning speed (with a button to over ride the programming if we had to turn really fast). We used gyros during autonomous, but not when our drivers took over.

In conjunction with Team 716's two-motor gear boxes (non shifting design
using drill and black motors from the Chief Delphi White Papers), our robot
was fast and maneuverable this year.

As it turned out, we also had some luck that the six wheel design
contributed to. Originally we hadn't planned on going up onto the platform
to hang, but then it turned out to be really hard to grab the bar from the
floor. One of our students discovered that we could do a wheelie (by backing up and then quickly going forward) and climb onto the platform which made it possible for us to hang quickly.

We had wanted to direct drive the middle wheels from the gear box, but we
couldn't fit the gearboxes (with drill motors, transmissions and gear boxes) side by side, so we wound up driving all six wheels with chains. It turned out to be very reliable using 1/4" chain. Basically the drill/black motor combination drove all three wheels on each side, so we got full traction although only four wheels were on the ground at any one time.

Sorry I don't have any drive train pictures, but you can see our robot on
our web site at team980.com.

Thank you Teams 254, 60, 716 and 25 (and many other teams who have
helped us) for sharing your ideas. They were a big help!!!

Re: What teams have desgined a 6 wheel drive system?
 

Doug has gotten to the heart of the matter here.

The 6-wheel drive with the lowered middle wheel GREATLY increases the turning of the robot. I know MANY teams who implemented such a system.

My main question is...
What distance do you drop your middle wheel?

I spoke to Steve from 254 and he told me they use 3/16" (as Doug mentioned above). I spoke to others who said they use a full 1/2".

What does everyone else use?

Lately, in all my pre-season design efforts I've used 3/16. I don't really have any good reason for it; other than Steve said it works for them. (And I LOVE their robot in action...)

Anyone?

John

Re: What teams have desgined a 6 wheel drive system?
 

i've also heard 1/8"

Re: What teams have desgined a 6 wheel drive system?
 

Here are some pics of the drive system of the team 25 recent six wheeled modular monsters. The whole robot pic is the 2002 robot Silver Scorpion- that made it to the final 4 in Nats. The modular drive pic is from Evil Machine 1- the 2003 finalist. As we've learned we have made the drives modular so they can be detached as a unit and replaced quickly. The kids strip them down and reassemble them like a soldier does with a rifle. The drives have never failed- never. They are now obsolete and the next generation will be a little faster and a little more powerful, at least according to prototypes. We have some new ideas up our sleeves. ; )
WC

Re: What teams have desgined a 6 wheel drive system?
 

John-
Although it seems to make sense and would make design interesting we have never moved any of the center wheels from our machines out of line from the rest. We want the deep grab traction for the motors and pushing power. And I think any who play us will agree that the machines are speedy and maneuverable. We use two joystick tank drive on the machines and they can spin in place with no problem at all.

Perhaps the answer to this is the fact that we have such wide wheels (custom made from Skyway wheels) and a gearbox with great power. We are probably horsing the machine around so much when we turn that the coefficient of friction on the center wheel is negligible. We usually give the machines the "Big Mike" test- if they can shove him away they are strong enough. If we lowered the center wheel we negate the traction we are looking for back to 4 wheel drive.

WC

Re: What teams have desgined a 6 wheel drive system?
 

we dropped our middle wheels just .1", and it worked fine for us.

Re: What teams have desgined a 6 wheel drive system?
 

I've always imagined and wanted the opportunity to design and build, for anyone who's interesested (hint, hint, nudge, nudge), a six-wheel drivetrain that keeps them all at a single height, but uses omniwheels on the four corners. It seems like that's a simple solution for enhancing traction in the robot's direction of travel while minimizing additional friction in turning.

I'd be surprised if another team has not yet tried this method, though nothing springs to mind.

Re: What teams have desgined a 6 wheel drive system?
 

We lowered ours 3mm (close to 1/8") and we could spin like a top.

To the point of traction: if all the motors are geared together per side and then run to the wheels, the lowered center wheel does not reduce your tractive effort (pushing ability). A six wheel drive concept is like using powered castors. The design is such that the center wheels take most of the load and the outside wheels balance load when the CG is moved on either side of center. If the drive is designed correctly, you pushing ability is not reduced as long as all the items touching the floor are powered.

Re: What teams have desgined a 6 wheel drive system?
 

Team 40 used that method this year.
I seem to remember them turning pretty well.

Now for some editorializing:
In order to push competitively in this competition, one needs as much tractive force available as possible.

Tractive Force = Wheel Coeff. x Normal Force

Normal Force is limited to the weight of the robot (and whatever the robot is able to pick up. In order to maximize Tractive Force, we want our wheels/treads/whatever to have the MAXIMUM coefficient of friction possible. (Many teams use high traction belting, or pneumatic tires).

Here is the kicker -- I have NEVER seen an omni wheel that can compete with straight up, high traction wheels when it comes to coefficient of friction. So... if you use omni-wheels on your robot, you are "wasting" normal force. You have weight sitting on "low" traction wheels, and have decreased your tractive force.

The GREAT thing about the 6WD configuration, is that it allows the robot to turn like crazy, but ALL the robot's normal force is sitting on driven, high traction wheels. It's the best of both worlds! Turning + Pushing!

Note: Casters pose the same problem. If you have weight resting on "non-driven wheels" you're shooting yourself in the foot again, when it comes to pushing matches.

For more information about WHY the 6WD, lowered middle wheel configuration turns better... check out Chris Hibner's turning whitepaper. He's got GOLD in there: http://www.chiefdelphi.com/forums/pa...le&paperid=222

It's physics,
John

Re: What teams have desgined a 6 wheel drive system?
 

Wayne,
First off, I'd like to say I'm a huge fan of your team's machines. You guys are great.

The amazing turning ability of your machines is DEFINITELY linked to your "wide" wheel configuration. It's all physics (you can see it in Chris Hibner's whitepaper, I linked in my previous post).

I disagree with you on one point:
I would argue that your 6WD configuration isn't helping you get more traction. For the most part, surface area isn't a factor in tractive force. (F = mu x N) <-- No "A"

For our applications (rubber on carpet) these are NOT perfect surfaces, and cannot be expressed perfectly with the above equation. They are intertwining meshes. This would help explain getting "more" traction using 6WD.

However, I would argue that you're not getting very much more.
Is there any chance you'd be willing to help with a little experiment?
It is for the mutual sharing of knowledge to benefit the entire communitty. ;)

Wayne, do a straight up pull test with one of your robots. Record some values for it's maximum linear force. THEN, have one of your kids remove the 2 middle wheels from your drive modules (put them on top of the robot somewhere, so the normal force doesn't change). Now try the pull test again.

I hypothesize that your second test will be within 10 lbs of the first test (if not closer).

If you participate in this little experiment, I know I'd be (along with many others) very interested in the results.

Thanks,
John

PS - Your gearbox isn't any more over-powered than the rest of ours! 2 Drills + 2 Chips = 1552W = 2.08 Hp. How you guys manage to gear it so fast, yet still push so hard is beyond me. Up here on 229, we're genuinely convinced you guys are defying physics somehow. Are you sure you don't have 2 extra drills tucked inside that thing somewhere? ;)

Re: What teams have desgined a 6 wheel drive system?
 

Running into something at 15-18 fps probably helps explain that to some degree :ahh:

Re: What teams have desgined a 6 wheel drive system?
 

Momentum is one explanation but...
I watched them (From a standstill) win pushing matches against teams they shouldn't have! It was incredible...

Re: What teams have desgined a 6 wheel drive system?
 

John, on a purely non-scientific note, one needs to watch very closely to see how 25 gets that "little extra" in a pushing match. In the past two years, for part of (nearly) every pushing match they are in they are actually not moving at all. Once they are in a desired position they stand still with almost no exertion on the motors or battery at all. As to how they get that done, you'll have to ask 25, but I do know, that at the end of a match they generally have happier and cooler drive motors than most opponents not to mention more left in the battery.

Re: What teams have desgined a 6 wheel drive system?
 

against who or what matches? so i can see it on soap (Very interested in this machine)

New 6wd Question : IF the Robot Keeps Teterring on The Center Wheels then doesn't the Center Of Turning Keep Changing From a Point in the Middle of the 4 wheels Touching the ground, then another center when the other two wheels make contact and the previous two rise off the ground?



2nd New 6wd Question: i Noticed Several teams who executed a 6wd, didn't use all 6 wheels of one type (8' 12' 6' 3' there were all over the place, 233 comes to mind) How does this effect the 6wd?


3rd New 6wd Question: Also Noticed like in the previous Question that some teams went out of there way to have a lower traction wheel in the middle, why and how important is it?


-Osc-

i Like the 2003 25 Bot Alot more , flew an like eagle and look cool too (Threatening);)

Re: What teams have desgined a 6 wheel drive system?
 

yeah we have 4 drill and 4 chips, can't believe it took someone so long to figure that out on CD. just kidding...

Wanna know a big secret? Yes, we are powerful and all that, but in a pushing match, we use BRAKES(used very less this year, but in last years game it was the thing). I am just starting to learn more about drive trains, torque etc etc from you guys, so maybe I can figure out how on earth we're so fast and powerful at the same time. I think I will ask one of our tradesmen...
-Bharat

Re: What teams have desgined a 6 wheel drive system?
 

John- you're probably right on the physics of it all. One thing that I do notice is that the rubber of the tires is quite soft and wears quickly- possibly just enough to naturally create the surface needed. In any case it works. And when the wheels get some pressure pushing back on them they probably flatten a little and grab better. I'm not sure I want to test it however although all this discussion gave me an idea about recycling some of the old tires we have layiing in the shop.

As for experiments- it IS more fun to just have the machine throw Big Mike around.......

WC

Re: What teams have desgined a 6 wheel drive system?
 

Of course now every robot in the world is going to try to shove us around- thanks Rich !!!

As Bharat posted- we use brakes. At the flip of a switch we can lock up the entire drive train. It is very simple. Of course knowing when to use the brake is the key and that's what the drive team works out. Since we have six, wide wheel surfaces in contact with the ground I believe we get a little edge on robots with normal wheels.

And no, we dont defy the laws of physics but we do have a genius tech guy on the team named Mike Lubniewski who devotes a lot of time to thinking about improving the drives each year. (hence Bharat's avatar)

WC

Re: What teams have desgined a 6 wheel drive system?
 

And its probably the only thing that can throw him around...

As for the wheels, the custom made Skyway wheels with diamond cuts on them makes them stick to the carpet like crazy(traction). Then, Straight-cut spur gears along with needle and ball bearings ensure all the motor torque gets to the wheels with minimal parasitic loss...

Thats the explanation I got from our tradesmen.

Re: What teams have desgined a 6 wheel drive system?
 

My team is thinking about 6 wheels. Has anyone experienced any problems with it? Does it go straight when its supposed to? Is turning smooth? Those are our main concerns right now. Thanks.
-gavin-

Re: What teams have desgined a 6 wheel drive system?
 

6-wheel drive is probably the best way to go. It will drive straight if your chains and everything is tensioned properly. The only problem with driving straight is in the gearbox of the Drill motors. But thats only in the gearbox and is easily fixable. For turning the best to do that is to lower the middle set of wheels so that when you turning you are basically turning on those two set of wheels. We haven't had any sort of problem with our 6-wheel drive systems yet.

Re: What teams have desgined a 6 wheel drive system?
 

if you're talking about the directional bias that the drills have (i.e., they spin slower in reverse), its actually built into the drill motors themselves.

Re: What teams have desgined a 6 wheel drive system?
 

I thought that was already true ... oops :)

Re: What teams have desgined a 6 wheel drive system?
 

is the bot still in tact or what?
if it is it would help me immensely if you could get a few pics of the motors and the way that it was all put together. if this is at all possible please help me out!!! thanks!

Re: What teams have desgined a 6 wheel drive system?
 

294 has been working on a prototype 6-wheel drive.