Crazy Drive Train Ideas

[M.Wong]

Originally Posted by ,4lex S.

BALL DRIVE!!!

One large ball with a traction wheeled motor rolling said ball in the y direction, and another in the x. I can't see this ever being practical, but it would be fun to build and program.

We did this for a community outreach robot. Instead of treaded wheels we used omni wheels. At first, he was designed to balance on it, but we decided to put some casters on him. The large basketball we used got worn down to the fabric.

[548swimmer]

Originally Posted by M.Wong

We did this for a community outreach robot. Instead of treaded wheels we used omni wheels. At first, he was designed to balance on it, but we decided to put some casters on him. The large basketball we used got worn down to the fabric.

How did you secure the ball? That's the only issue I have with ball drives.

[Lil' Lavery]

Originally Posted by JesseK

I don't understand why all teams want the drive train to do everything for mobility. If the rules allow for it, why has no one even prototyped something like a tethered Quad Rotor that lifts off and gets the game object? Sure, the thing would probably get beat up during a finals match but the sheer success in prototype will spur a LOT of creative thought come build season. Of course just implementing a quad rotor with limited amounts of motors is a feat and requires its own innovations worthy of patents and PHD's, heh. Then there's the control component, which many programmers would salivate at the chance to do, and the sensor feedback component which boggles the mind of even the smartest professionals.

If only a tether wouldn't prevent them from doing this...

[Hawiian Cadder]

augers would work, two augers with oposite direction helixes, the spin the opposite direction of each other to go forward or backward, altering the speed that each one drives would achieve holonomicacy. to go sideways, both spin in the same direction, due to the way the screws are set up it will not be vulnerable to pushing from one side while traveling at 90 degrees like mechanum is to some degree, i think ill ask on Q&A next year if that would be legal.

[Collin Fultz]

Originally Posted by Hawiian Cadder

drives would achieve holonomicacy.

/tangent/

I'm not 100% sure this is a word, but if not, it should be. Or would it just be holonomicy? Either way, it's finding it's way into my vocab.

/tangent/

[gblake]

Originally Posted by Collin Fultz

/tangent/
it's finding it's way into my vocab.
/tangent/

/tangent//tangent/

Argh!!!!!! Please say it isn't so!

Good words already exist. Take the time to discover and use them. Vocabulary and writing skills are important. Practice using existing words precisely instead of cluttering your vocabulary with ambiguous jargon that only creates the illusion of technical information.

FYI - Most good employers care greatly about this....

/tangent//tangent/

Blake

[Jared Russell]

Originally Posted by Hawiian Cadder

augers would work, two augers with oposite direction helixes, the spin the opposite direction of each other to go forward or backward, altering the speed that each one drives would achieve holonomicacy. to go sideways, both spin in the same direction, due to the way the screws are set up it will not be vulnerable to pushing from one side while traveling at 90 degrees like mechanum is to some degree, i think ill ask on Q&A next year if that would be legal.

Think of the interactions between the "ribs" of the auger and the ground. In order to move, there will necessarily be slip. Slip means that you have (sometimes significantly) less available tractive force - remember the differences between static and dynamic friction. So you will accelerate more slowly - and push with less force - than with a mecanum wheel.

Additionally, it is hard to find a material that can slip against the carpet, yet still have traction, yet won't destroy either the carpet or itself very quickly. The analogy would be if you made a "kiwi" drive (wheels at 45 degree angles to the body) with regular wheels - everything would scrub the ground all the time. It kills your wheels, it kills the carpet, and it kills your efficiency.

All of this goes out the window (somewhat) if you are driving in sand, but otherwise I would think long and hard before implementing this.

[Tom Ore]

Originally Posted by Hawiian Cadder

augers would work, two augers with oposite direction helixes, the spin the opposite direction of each other to go forward or backward, altering the speed that each one drives would achieve holonomicacy. to go sideways, both spin in the same direction, due to the way the screws are set up it will not be vulnerable to pushing from one side while traveling at 90 degrees like mechanum is to some degree, i think ill ask on Q&A next year if that would be legal.

Not sure if this link has been posted earlier in the thread but here it is:

http://www.youtube.com/watch?v=L3NGCL-efRM

[Chris is me]

Originally Posted by Tom Ore

Not sure if this link has been posted earlier in the thread but here it is:

http://www.youtube.com/watch?v=L3NGCL-efRM

You'll note the machine in the video is running on a surface that deforms under the auger-wheels. How do kinematics when the surface fails work differently than on a stable carpeted surface?

[Ian Curtis]

Originally Posted by Chris is me

You'll note the machine in the video is running on a surface that deforms under the auger-wheels. How do kinematics when the surface fails work differently than on a stable carpeted surface?

This video seems to say it works just as well.

If any team wants to mold some enormous Archimedes screws like those, I'd bet you win some kind of technical award. Making weight would be fun though...

[Jared Russell]

Originally Posted by iCurtis

This video seems to say it works just as well.

If any team wants to mold some enormous Archimedes screws like those, I'd bet you win some kind of technical award. Making weight would be fun though...

Nobody is saying you can't get a screw drive to move - just that it will be much, much more inefficient than just about anything else on terrain that isn't sand or snow.

[JamesCH95]

With 130+lbs on the screws good luck not damaging the carpet from driving or getting pushed around.

[Tom Ore]

Originally Posted by JamesCH95

With 130+lbs on the screws good luck not damaging the carpet from driving or getting pushed around.

From the video, it looks like a rather high lead thread is required to get the speed ratios correct (fore/aft versus sideways). Maybe a multi start thread could be used to keep the lead high but provide more surface area in contact with the ground.

[gblake]

Originally Posted by JamesCH95

With 130+lbs on the screws good luck not damaging the carpet from driving or getting pushed around.

Maybe someone can have fun making an omni/mechanum auger. Get a big hollow drum and mount (or cut slots to hold) a ribbon of ball bearings, or of rollers, in a barber-pole spiral around the drum's outer surface.

I'm not saying it would be ideally suited for any games other than those containing the fabled FRC water hazards; but it could be fun to make. If you chose the materials carefully, you might be able to create a fun off-road machine that isn't stymied by swampy terrain, and that is also at home on FRC carpets.

Blake

[theprgramerdude]

Originally Posted by JamesCH95

With 130+lbs on the screws good luck not damaging the carpet from driving or getting pushed around.

Pushed on a screw drive? Bahahahahahahahahahahaha