Crazy Drive Train Ideas

[Bjenks548]

A few members of our team are working on crazy drive train ideas. While we have plenty to work with currently, I hope to get through them and onto more. If you have any weird drive train ideas please post them here and do your best to describe them. I don’t want anything that’s already been seen around such as nona-drive and kiwi, I want brand new ideas. We plan to CAD and build all these drive trains using the kit of parts c-channel this summer. Please post any ideas, thanks.

[,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.

[Chris is me]

I have a really crazy drivetrain idea. Instead of 4 wheels, put 6 wheels on a robot, and make the center one lower! That way, robots will have a shorter wheelbase for turning but high traction all around! :rolleyes:

Of course I'm kidding, but I've always wondered why people take the "let's do something weird for the sake of it" approach to prototyping, rather than engineering a drivetrain that tackles a design aspect differently. I think you should totally build a crazy drivetran, don't get me wrong - but maybe it would be a better exercise to figure out what current drivetrains you use don't do very well, and then figuring out a new drivetrain optimized toward different design criteria than the bog standard.

The latest innovative drivetrain in FIRST (nonadrive) probably wasn't thought of by going "hey dude, what if we did THAT?". I imagine they specifically looked at a way to accomplish something not present in a 6wd (strafing) without some of the drawbacks of drivetrains designed for that (swerve, mecanum). Maybe you can do the same thing - and come up with something incredibly crazy, but useful too!

[BrendanB]

Well, since Winnovation stole an idea I had in 2007 of 6 wheel crab drive I guess 8 wheel crab drive is the next new thing of the future! :D

[ttldomination]

The latest innovative drivetrain in FIRST (nonadrive) probably wasn't thought of by going "hey dude, what if we did THAT?".!

I don't know, but that sounds perfectly plausible to me. Some of the best ideas on my team have come from people just talking about hypothetical ideas or things that would be cool, and then someone sees the implementation in their head, and it just takes off.

- Sunny

[dodar]

i think it would be cool to see a crab-drive tankdrive robot :ahh:

[Arefin Bari]

Here (http://www.chiefdelphi.com/media/photos/15197) is a link to the ball drive Team 45 came up with back in 2003. Also, search for ball drive under CD-Media to see more pictures.

Team 179 and 1345 collaborated in 2009 and built a crab drive. The crab drive also drove like a tank drive. Is this what you meant?

[BrendanB]

i think it would be cool to see a crab-drive tankdrive robot :ahh:

I believe team 2342 Team Pheonix from Nashua/Merrimack New Hampshire did a design in 2009. It was a standard crab drive robot but with added code allowing to act as a crab, tank, and ackerman steering and even some slight combined variations.

Is that sort of what you were thinking of?

[Chris is me]

I believe team 2342 Team Pheonix from Nashua/Merrimack New Hampshire did a design in 2009. It was a standard crab drive robot but with added code allowing to act as a crab, tank, and ackerman steering and even some slight combined variations.

Tons of crab drives do that. Not to take anything away from the 5 or 6 teams each year that tell me their drivetrain is a crab drive AND a tank drive, but that's pretty standard.

I think he meant swerving tank treads or something.

[BrendanB]

Tons of crab drives do that. Not to take anything away from the 5 or 6 teams each year that tell me their drivetrain is a crab drive AND a tank drive, but that's pretty standard.

I think he meant swerving tank treads or something.

Yah I was confused as well thinking of the same thing, "aren't all crabs tank drives?"

I think it is just one of many things that makes me crack up back on pit scouting or alliance strategy. "Our robot has a very low center of gravity!" That is great, but how does that large heavy steel arm play into that?

[mwtidd]

4 wheel crab with actuator legs (http://www.youtube.com/watch?v=IMmJtw0XYzk)

lets make the legs 3-position pneumatics.

and while we're at it, figure out some way to mount the bumper is its '10 legal.

or the beautiful rotating mecanums would be nice
i have a design that could be driven by one set of motors and still be holonomic

[Hawiian Cadder]

Hoover-craft....

i would actually like to see a robot with a bike drive train, even the most basic bicycles have at least a couple different gear ratios, and there are some bikes with upwards of 24.

[jamie_1930]

I think I have exactly what you are thinking of this was one of our programmer's, dana, idea in 2009. He called it serpentine drive and was designed to slide across the regolith, similarly to a snake. I hope I can explain this well enough for some people to get, and I'll try and follow it up with some of dana's prototyping of the drivetrain. You make multiple wheel assemblies that would include two wheels, parallel to one another and unpowered, with a center pivot in the middle of the two. Now you would have the center pivot offset from the center of a gear, then put a series of this in a line with eachother, connected with springs to the front and back of each and idler gears inbetween to maintain direction. Each of the assemblies would then be offset slightly so that when the whole thing was powered by a single motor the wheel assemblies would travel in a wave.

[Hawiian Cadder]

i just came up with another one, make a robot that is entirely encased in a hollow sphere with omni wheels on every corner facing outward, to drive the main part of the robot drives the inside of the sphere, if we ever get a water competition this would be highly helpful i think.

[Aren_Hill]

Well, since Winnovation stole an idea I had in 2007 of 6 wheel crab drive I guess 8 wheel crab drive is the next new thing of the future! :D

The Idea has been lurking around in my head for longer than that, Dillon just made it feasible by making tiny modules ;)

[Jared Russell]

You have to be careful that you think about this in the right way. There have been all sorts of crazy drive trains in FIRST. Ball drives. All sorts of swerves. Active and passive suspensions (especially this year). Walking file cards. Ball differentials. CVTs. 2 speed (AM-style), 3 speed (DeWalt + 222 ball lock shifter), 4 speed transmissions (33). Brakes. Triwheels. Traction wheels, inflatable wheels, omni wheels, mecanum wheels, treads. Nonadrive. The list grows every year.

Some of the above have been used to great effect on certain robots. Others tend not to do as well. What's the difference?

The teams that succeed on the field don't generally seek to innovate their drive systems for innovation's sake - they instead analyze the game and what they want their robot to do well and use that analysis to drive their choice of drive system. In other words, before trying to think of off the wall ideas, think of what possible situations would cause the "tried and true" FIRST drive trains to fall short.

Steps? Driving on sand? The return of regolith? What if you decide you need holonomic/swerve-like agility with extreme pushing power (especially if you decide that your team isn't a good fit for swerve, either financially or because of fabrication resources)? How can you ensure that nobody can cause your robot to turn if you don't want it to?

(I'm speaking about drive systems you would actually want to use on a competition robot here. In the offseason, or for demo purposes, sure, anything goes. But the teams that succeed on the field more often than not have competition on their minds before they go and prototype.)

[Bjenks548]

While I know that this is not the best idea as far as making a game applicable off season part, with summer coming and the GDC refusing to give me a game hint to work with, I am bored and need something to do. Please do not criticize what we are doing and keep the post to drive train ideas and discussion.

[JesseK]

To sum up the critics of this thread:
"An innovation needs to be set to a strategy, solve a specific problem and be practical before the design even starts."

Thank God DaVinci didn't think that way, nor did these guys (www.irisengine.com)
<Philosophy>
The methodology of complex innovation has been around since the Rennaisance Era, and didn't start with a specific problem to solve. The problems are abstract, even in the FRC Drive Train realm: design a drive train that is both agile and has high tractive power. The reality is that solving the problem is an excellent lesson in Innovation itself and the lessons learned will carry further than just the FRC season. The biggest lesson is that there is never a silver bullet to solve every problem in a mechanical system. Given that now is the Prototyping Season, this is a fun discussion with perfect timing.
</Philosophy>

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.

0.02

[Jared Russell]

While I know that this is not the best idea as far as making a game applicable off season part, with summer coming and the GDC refusing to give me a game hint to work with, I am bored and need something to do. Please do not criticize what we are doing and keep the post to drive train ideas and discussion.

I'm sorry if I came off as criticizing - I think that no matter what you decide to do, prototyping in the off season is very beneficial and a lot of fun! True innovation doesn't necessarily require a concrete problem first, but history shows that necessity is the mother of invention quite often.

I was just throwing out that if you want to prototype for fun and to for practice, why not also practice analyzing a FIRST-like game challenge. While the GDC hasn't given hints towards 2011 yet (and given past history, they are unlikely to do so until much closer to kickoff), history shows that elements of past games tend to be re-used in new and slightly different ways. Pick a game that you aren't familiar with, analyze some of the technical challenges, and think of ways to solve them.

Either way, you'll have fun and learn a lot.

[Andrew Schreiber]

To sum up the critics of this thread:
"An innovation needs to be set to a strategy, solve a specific problem and be practical before the design even starts."


An idea need not solve a specific problem but a design should. That problem can be completely off the wall or it can be realistic. A water game, not so realistic for FRC but figuring out how to navigate under water would be useful for NURC.

I suppose there are two ways of looking at this, either you can define a problem and develop a solution or you could define a solution and develop a problem. Personally, I prefer knowing my problem first as it means I can more easily break it down into sub problems to be solved.

As for crazy drive trains, why not do a definitive test 14 wheel drive (703) compared to 6wd or 8wd or 2wd? It might be that having more wheels has benefits that we can't see easily.

As far as problems you might want to look into solving I would suggest climbing stairs (6" or more) or navigating on a narrow area (see 2004 field centerpiece for example). These are challenges a lot of FRC teams have never faced and none of the students still on teams have faced.

[Bill Beatty]

Speaking about wild drives, does anyone remember and have any information on a wild drive I saw on a web cast a few years ago? It had three flats driven between two disks. I think the robot was decorated to look like a cow. I still haven't figured out just how that thing worked. A picture would be great.

Mr. Bill

[MrForbes]

Speaking of stairs, designing an FRC sized legged robot would be a great exercise, and if you can figure it out, might even work in a real game.

My son's friend Matt made a smaller one, and although the mechanics would probably have to be quite different (crankshafts/connecting rods for legs?) the programming could be similar. You never know where this kind of thing will lead.

http://www.technewsarizona.com/Article.aspx?d=20091220&t=0600

[Alex Cormier]

Speaking about wild drives, does anyone remember and have any information on a wild drive I saw on a web cast a few years ago? It had three flats driven between two disks. I think the robot was decorated to look like a cow. I still haven't figured out just how that thing worked. A picture would be great.

Mr. Bill

That would be team FRC 276. I had the pleasure of competing against them in 2003, 2004, and 2005 at Buckeye.

http://www.chiefdelphi.com/media/photos/15308

[Mr. Tech Vike]

i think it would be cool to see a crab-drive tankdrive robot :ahh:

my team did that this year we programed for a skid-steer and crab. all we had to do is make sure the wheels were lined up and in hae right direction (you can get turned around pretty easy) but all we had to do is hold down a button on our joy sticks.

[JamesCH95]

I've seen teams with two sets of tank drives oriented 90deg apart with the ability to switch between the two. That is an interesting problem to think through or build.

Can you make a robot that moved like an inch worm?

What about a tread design like The Pack Bot (http://www.youtube.com/watch?v=eaP0waiz43w)? Talk about being robust...

Have fun with your prototyping!

[Hawiian Cadder]

looking at the challenges up above i believe i have found a form of locomotion that would satisfy all of them.

a robot that uses Augers to contact the ground.


http://www.youtube.com/watch?v=1uynmApjhWI

better yet, a robot of this type would be somewhat holonomic if the augers were separately driven, it would also have incredible amounts of traction, even more than tank treads i believe. it could go up stairs if the auger diameter were large enough, and if the Augers were hollow or could float, it might contribute to a water game. i suspect that depending on the pitch of the augers, not much gear reduction would be needed for a working robot, a single AM stack-box would probably do the trick.

[EricH]

Build a drivetrain that can handle corn. You just might need it...

[jamie_1930]

i just came up with another one, make a robot that is entirely encased in a hollow sphere with omni wheels on every corner facing outward, to drive the main part of the robot drives the inside of the sphere, if we ever get a water competition this would be highly helpful i think.

This is a drive train I've been pondering for a while and I would love to make it.

[CENTURION]

This is basically what I've been doing for the past few weeks straight :P

Specifically, I've been attempting to find a way of making a demo/promotional robot that our team can show off to schools, potential sponsors, and the general public (especially when we do recruiting for our summer camp).

I personally have been wanting to tackle the problem of an off-road sort of drivetrain, so I've been experimenting.

For now my favorite solution is off-road swerve/crab drive, using two wheels on each pod (ok, I'll admit, the two-wheels part is mostly to make it look cooler, but it would have it's benefits: traction, weight distribution on soft material, etc)
Each pod would be individually rotated via an FP or Window motor, and would raise and lower via a pneumatic piston and some guide bars. (the pistons could be pressurized somewhat to create a passive suspension system).

I will upload some sketches and better explanations later...

[548swimmer]

This is a drive train I've been pondering for a while and I would love to make it.

http://xkcd.com/413/

'nuff said.

[Chris is me]

For now my favorite solution is off-road swerve/crab drive, using two wheels on each pod (ok, I'll admit, the two-wheels part is mostly to make it look cooler, but it would have it's benefits: traction, weight distribution on soft material, etc)
Each pod would be individually rotated via an FP or Window motor, and would raise and lower via a pneumatic piston and some guide bars. (the pistons could be pressurized somewhat to create a passive suspension system).


You may be interested in this whitepaper (http://www.chiefdelphi.com/media/papers/1552). 1114 made a swerve drive somewhat similar to this in 2004.

[jamie_1930]

http://xkcd.com/413/

'nuff said.

That is actually infuriating that is exactly how I wanted to go about it, minus the webcam although it is a nice addition.

[NickE]

i just came up with another one, make a robot that is entirely encased in a hollow sphere with omni wheels on every corner facing outward, to drive the main part of the robot drives the inside of the sphere, if we ever get a water competition this would be highly helpful i think.Have fun putting bumpers on that robot. ;)

[daltore]

http://xkcd.com/413/

'nuff said.

First let me say that I dearly love XKCD and Randal Munroe. But he got it wrong. Just take a good look at those "omni wheels". They're mecanum...

I've been looking into making a drive train I recently read about in Servo magazine: Melty Brain. Basically, it's an effectively holonomic robot (overall it is, but instantaneous moments it isn't) that can be driven with only one wheel and one motor, but you can technically use as many wheels and motors as you want if you've got a fast enough processor. This site has a good explanation:

http://www.spambutcher.com/meltyb.html

I want to preface this description with the note that this drive train is absolutely terrifying, but if it's crowds you want, then crowds you'll have. The robot spins up really fast in a circle (no gear reduction on the wheels, in fact depending on wheel diameter, the CIM's might be a little slow) using the motor[s], and very precise timing allows you to vary the motor speed at specific points in the circle to effect a net vector that allows the robot to move around. If you think of it in terms of a polar graph, to go forward, you'e have a base speed, at 0, the motor would be going faster than that base speed, at PI/2 and 3PI/2, the motor would be spinning at the base speed, and at PI, the motor would be slower than base speed.

This is a fairly easy drive train to build (although it's harder with the size of robot you're building, you have to make sure the center of mass is relatively stable and all of your frame connections are very solid, otherwise the robot might try to rip itself apart). The hard part of this type of drive train is the code. You have to have either one accelerometer and know its radius away from the center of mass (the axis of rotation), or two accelerometers inline and know the distance apart (I like that one because it means you can change batteries without necessarily recalibrating). You measure the centripetal acceleration with the accelerometers, and with the radius information, you can figure out angular velocity. You effectively integrate that (multiply the calculated angular velocity in one loop by the amount of time between loops, then do it again next time and keep a running sum), and you'll end up with your angle. The angle is used to calculate wheel speed. The motor control is very simple, and can in fact be done with a PWM-capable pin and a large Darlington transistor or power transistor and a gate driver (the Darlington transistor is usually used because you can pick one up at Fry's for under $5).

I'd suggest making a small one (at least at first, probably a good size to keep it though) out of a small piece of 1/4" Lexan or plywood and a Fisher-Price motor and a Lite-Flite or equivalent high-traction wheel, and seeing how it goes before you think about moving up to anything bigger and more dangerous. It's been done before, but all for antweight (and one beetleweight) combat robots, so it would be cool to see what you guys come up with to do with it. An idea I had was to use a line of LED's and write messages in the air while it's spinning, but there are probably lots of other things you could do with it.

[Chris is me]

That is actually infuriating that is exactly how I wanted to go about it, minus the webcam although it is a nice addition.

Why is it infuriating?

Anyway, if you want a crazy drivetrain idea... Figure out a 4wd drivetrain that is not vulnerable to pushing that goes over the bumps that can turn. I wish I figured that one out...

[JamesCH95]

Figure out a 4wd drivetrain that is not vulnerable to pushing that goes over the bumps that can turn. I wish I figured that one out...

One that uses ackerman steering with zero mechanical trail :)

[Chris is me]

One that uses ackerman steering with zero mechanical trail :)

It also has to zero point turn, sorry. :P

I saw one solution this year. Very forehead-slap moment for me. (Edit: I think with some adaptations, that same drivetrain could outperform a Nonadrive. Wait... I think I just inspired myself. CAD time!)

[JamesCH95]

Pictures of the solution? Or Nonadrive for us un-initiated?

[Chris is me]

Pictures of the solution? Or Nonadrive for us un-initiated?

*spoiler alert for teams that want to guess :)*

The pictures available don't show it, but 195 had a drivetrain with 4 high traction wheels. To turn, they had drop down omni wheels in line with the back wheel axles. It was an extremely clever solution that I feel stupid for not thinking of when I wanted a 4wd this year.

As for the adaptation, let me work on that one for a bit.

[Andrew Remmers]

I would like to make an adaptable drive train that is easily suited for most kinds of game play or game types

[JesseK]

What do you mean by "outperform" the nonadrive? Considering that the nonadrive effectively addresses a multitude of issues with both omni and 4wd while combining their strengths (and even manipulating a perceived weakness of 4wd), saying a drive train will outperform the nonadrive is a very broad, boastful statment...

Additionally, until you've driven a drive train with "modes" (linkage in 2008/09, nonadrive as implemented in '10), you really don't get a feel for the true power of a manipulatable center of rotation.

[Chris is me]

What do you mean by "outperform" the nonadrive? Considering that the nonadrive effectively addresses a multitude of issues with both omni and 4wd while combining their strengths (and even manipulating a perceived weakness of 4wd), saying a drive train will outperform the nonadrive is a very broad, boastful statment...

Additionally, until you've driven a drive train with "modes" (linkage in 2008/09, nonadrive as implemented in '10), you really don't get a feel for the true power of a manipulatable center of rotation.

The random idea I thought of when I made the post had the capability of doing particular features better than a Nonadrive base. It was rashly typed, yes, but also an example of the kind of thinking that could get you to think up your next "creative" drivetrain. Start looking at drives that arent 6-drop and what advantages they have, and how to work around their drawbacks. Evolution is innovation.

[CENTURION]

ok, here's a few sketches if you care to take a look:

This is 8-wheel swerve drive, with modules that can be raised and lowered (you can ignore pretty much all of the math and notes on there, that was me doing figuring on amounts of material for the whole bot)

(I will hopefully have Sketchup models done soon)

http://s226.photobucket.com/albums/dd230/evbunke/?action=view&current=001-3.jpg

This is a triangular(ish) robot, with a single swerve module in the middle, and basically a kiwi drive around it (three omni's, each powered by a FP/Window Motor). The only reason the omni's are powered is to keep the robot from spinning wildly when you try to rotate the swerve module.

http://s226.photobucket.com/albums/dd230/evbunke/?action=view&current=002-1.jpg

[548swimmer]

*spoiler alert for teams that want to guess :)*

The pictures available don't show it, but 195 had a drivetrain with 4 high traction wheels. To turn, they had drop down omni wheels in line with the back wheel axles. It was an extremely clever solution that I feel stupid for not thinking of when I wanted a 4wd this year.

As for the adaptation, let me work on that one for a bit.

We used that method as well, and it made so much sense once someone said it that everyone else was amazed they didn't figure it out themselves. Though, if you want to be picky, it is technically a 6 wheel drivetrain.

[Bjenks548]

So I have another drive train running through my head. I was wondering what gear ratio would be used to power an individual wheel using a ban bot moter and what it would be for a fisher price moter. Also I thought i remebered that we only get 2 bb and 2 fp moters, is that right?

[JamesCH95]

So I have another drive train running through my head. I was wondering what gear ratio would be used to power an individual wheel using a ban bot moter and what it would be for a fisher price moter. Also I thought i remebered that we only get 2 bb and 2 fp moters, is that right?

ban bot motor? err... :confused:

Yes, teams typically get 2 FP motors.

What sized wheel?
How fast do you want to go?

Divide the circumference of the wheel by 85% of the motors free speed (a rough approximation for full speed under load) then multiply by the gear ratio (1:15 reduction would mean multiplying by 1/15th) and there's your top speed.

Generally 5ft/s is a good pusher robot, 8ft/s is quick with good acceleration, and 11ft/s is FAST with moderate acceleration.

[Chris is me]

ban bot motor? err... :confused:

For example, this year's RS-555's that no one used.

Generally 5ft/s is a good pusher robot, 8ft/s is quick with good acceleration, and 11ft/s is FAST with moderate acceleration.

With 4 CIM motors. Your acceleration will take a hit as will your pushing ability *using other motors*

[Hawiian Cadder]

if anyone knows how a auger driven drive would be affected by the rules, my team is seriously considering it, it would be holonomic, with incredible traction, it could handle soft terrain as well as bumps. we are looking at ice fishing augers right now for cheapness and availability.

[Chris is me]

if anyone knows how a auger driven drive would be affected by the rules, my team is seriously considering it, it would be holonomic, with incredible traction, it could handle soft terrain as well as bumps. we are looking at ice fishing augers right now for cheapness and availability.

Unfortunately, the metal or plastic digging into the carpet would have been an illegal traction device this year, if I understand correctly.

[Alan Anderson]

if anyone knows how a auger driven drive would be affected by the rules, my team is seriously considering it, it would be holonomic, with incredible traction, it could handle soft terrain as well as bumps. we are looking at ice fishing augers right now for cheapness and availability.

Use mecanum wheels. They work based on almost exactly the same effect, and they have two major advantages. First, they are carpet-friendly. Second, they will actually work. :rolleyes:

[M.Wong]

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]

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]

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 (http://www.youtube.com/watch?v=MvRTALJp8DM)...

[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]

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/

[Jared Russell]

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.

[gblake]

/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

[JesseK]

If only a tether wouldn't prevent them from doing this (http://www.youtube.com/watch?v=MvRTALJp8DM)...

Make an offseason t-shirt bomber and it can do that ;). Make it a gimbaled tilt-quadrotor and then it can do spins while flying on it's side to wow the crowd in a match. Heh, make it a gimbaled quad-tiltrotor powered from a single motor and you can write your meal ticket for life almost. (It's theorectically mechanically feasible, but quite complex to do.)

Then there's the element of autonomous maneuvers that the driver could command the quadrotor to do during the match. It brings about a systems range of questions, ranging from how the user inputs the command at the driver's station to how the quadrotor interprets an executes the maneuver regardless of its current orientation or flight path.

[lim shi hao]

how about combining all the omni-directional drive together??

[Tom Ore]

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]

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]

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. (http://www.youtube.com/watch?v=QnJhzNqWiME) :)

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... :p

[Jared Russell]

This video seems to say it works just as well. (http://www.youtube.com/watch?v=QnJhzNqWiME) :)

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... :p

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]

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]

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

[Bjenks548]

This video seems to say it works just as well. (http://www.youtube.com/watch?v=QnJhzNqWiME) :)

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... :p

Any idea on how it would work on corn?

[JamesCH95]

How about this? (http://www.wimp.com/robotsnake/)

[DinerKid]

How about this? (http://www.wimp.com/robotsnake/)

This will be my favorite robot of the day. That is totally sick. My mom walked by while i was watching it and thought it was real. I want to know what snake makes that sound though.

~DK

[penguinfrk]

Cam drive. Worst mobility, best entertainment quality. You can only rotate the wheels in one direction, and if the wheels are placed on out of phase, you have this crazy tumbling thing. If put on in phase, you have a sort-of robot low rider that can pounce onto objects. If put on reflected, it's like a carousel.

How cool!

[Bjenks548]

Haha as cool as some of these ideas are, like the snake one :yikes: , i was more looking for odd wheel arrangements like the close center wheel 6 wheel that 548swimmer posted a few weeks ago. We were also planing on making a jump drive before it even came on chief delphi, stuff like that.

[gblake]

How about this? (http://www.wimp.com/robotsnake/)Why is the snake surrounded by a blurry aura in that video? It is using a prototype cloaking device or...

Is the video perhaps a fake?

[JamesCH95]

Why is the snake surrounded by a blurry aura in that video? It is using a prototype cloaking device or...

Is the video perhaps a fake?

I think that's an artifact of the video compression.

I highly doubt that the video is a fake, here (http://www.snakerobots.com/index.html) is the inventor's website, with all of the earlier and later versions.

[penguinfrk]

Gallop (Cam) Drive (http://www.facebook.com/photo.php?pid=4811446&l=cf64014d70&id=790168604)

(Change the phase difference for Low Rider drive!)

[Katie_UPS]

I always wanted to see a big-wheel robot. :P

[theprgramerdude]

With high gear reductions and large wheels instead of small wheels and low reductions?

Turbo-fan powered drive?

[Bjenks548]

I always wanted to see a big-wheel robot. :P

How big of wheels? we had 12" this year and i think 107(maybe a different team I'm going off memory) had the same ones too.

[theprgramerdude]

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

Pushed on a screw drive? Bahahahahahahahahahahaha

[davidthefat]

Legs with legs


Nuff said

Here is a picture of it:

http://img215.imageshack.us/img215/3008/92304822.gif (http://img215.imageshack.us/my.php?image=92304822.gif)

[Mageofdancingdr]

Train drive, with pneumatics.

hook up pneumatic pistons to crankshafts and as the pistons go in and out they create torque on the axel. most powerful drive system ever.

[DinerKid]

Train drive, with pneumatics.

hook up pneumatic pistons to crankshafts and as the pistons go in and out they create torque on the axel. most powerful drive system ever.

It has been done with Vex a few times. The issue is that the system eats air like crazy.

http://www.vexforum.com/showthread.php?t=22813&highlight=pneumatic+engine

~DK

[JamesCH95]

Train drive, with pneumatics.

hook up pneumatic pistons to crankshafts and as the pistons go in and out they create torque on the axel. most powerful drive system ever.

The compressor is just about the least powerful motor in the KOP, so that drivetrain will be about the least powerful. It could have high pushing force though.

[Jared Russell]

How big of wheels? we had 12" this year and i think 107(maybe a different team I'm going off memory) had the same ones too.

You should see 522 :)

[Aren_Hill]

http://lh4.ggpht.com/_VlbXtV3WR_Y/R8t_AGqQUQI/AAAAAAAACgk/Dnu78KOfcvU/s640/DSC_3522.JPG

One of Mr Pat Fairbanks pictures from 08

[Trent B]

The compressor is just about the least powerful motor in the KOP, so that drivetrain will be about the least powerful. It could have high pushing force though.

Gotta love semantics.

It would probably have the most pushing force, most powerful over the time period where there is enough air in tanks. Over the whole match probably the weakest.

[Jared Russell]

FRC rules have traditionally allowed energy to come from 4 sources:

-Battery
-Stored air
-Stored gravitational potential energy
-Deformation of robot parts

The fourth one could make for an interesting drive system (a "wind up toy"). Albeit one that would take a lot of engineering to make safe enough - yet powerful enough - to be useful.

[JamesCH95]

Gotta love semantics.

It would probably have the most pushing force, most powerful over the time period where there is enough air in tanks. Over the whole match probably the weakest.

Hehe, I suppose it is a little semantic, but there is a lot to be said for using precise and correct language, especially in the field of engineering.

[AdamHeard]

Gotta love semantics.

It would probably have the most pushing force, most powerful over the time period where there is enough air in tanks. Over the whole match probably the weakest.

I'd argue pushing force is completely independent and unrelated to the power source.

[EricH]

Possible pushing force might be unrelated, as there is only so much traction available from a given set of wheels.

Given a non-traction-limited drivetrain, however, where you get the power from can make a big difference. For a pneumatic drivetrain, if you can't keep the tanks full, you'll lose pressure quickly. The compressor would probably have a hard time keeping up with pressure loss in that case. But a motor-driven drivetrain does not have that problem, at least until the battery dies.

[JamesCH95]

^ exactly like that EricH said, the total integral work possible (not including mechanical inefficiencies) using the compressor for a whole match is 10.1kJ, whereas running 1 cim motor at full power for the whole match is 47.3kJ. So one CIM motor is nearly 5 times as powerful, and with proper gearing can deliver the same pushing force as pneumatics would.

What this says is that you need a compressor powered by several CIM motors :p

[kgzak]

Mecanum swerve :yikes:

[buildmaster5000]

Mecanum swerve :yikes:

That would defeat the purpose of swerve: low traction omni drive is simply mecanum. The whole point of swerve is to have high traction omni drive

[kgzak]

That would defeat the purpose of swerve: low traction omni drive is simply mecanum. The whole point of swerve is to have high traction omni drive

we were talking about it for a test platform. that way programers have a robot that you can run a few different drivetrains without having to change anything. It kinda became a joke throughout the season because we didn't know whether we wanted swerve or mecanum. I realize that it is on of the most pointless designs.

[Mountain Man]

See below.

http://www.chiefdelphi.com/forums/showthread.php?threadid=86862

[Mageofdancingdr]

^ exactly like that EricH said, the total integral work possible (not including mechanical inefficiencies) using the compressor for a whole match is 10.1kJ, whereas running 1 cim motor at full power for the whole match is 47.3kJ. So one CIM motor is nearly 5 times as powerful, and with proper gearing can deliver the same pushing force as pneumatics would.

What this says is that you need a compressor powered by several CIM motors :p

what if you create a shifting mechanism between pneumatics and CINs, so you can push with pneumatics engaged and drive with the CIM motors?

also, when I was thinking of power, I was thinking of the power during the time before the tanks ran out, which I think would be more powerful than the CIMs during the same time period (how would I do the math to find out though, where is the power rating for a cylinder?)

[Ether]

I was thinking of the power during the time before the tanks ran out, which I think would be more powerful than the CIMs during the same time period (how would I do the math to find out though, where is the power rating for a cylinder?)

The power you can get from pneumatics on FRC is limited not by the cylinder, but by the solenoid ⅛” NPT port diameter and maximum Cv of 0.32

You can use solenoids in parallel to mitigate this somewhat, but other fittings and line losses limit what you can achieve.

A CIM has a maximum power of 337 watts, but this can be sustained only briefly, not the entire match.

[JamesCH95]

what if you create a shifting mechanism between pneumatics and CINs, so you can push with pneumatics engaged and drive with the CIM motors?

also, when I was thinking of power, I was thinking of the power during the time before the tanks ran out, which I think would be more powerful than the CIMs during the same time period (how would I do the math to find out though, where is the power rating for a cylinder?)

It is possible to do what you've described, but it is probably more cost and weight effective to use a shifter transmission because you will be traction limited.

And... what is this? A student who wants to know how to the math?! I'm confused and terrified right now :D more on this later...

The power you can get from pneumatics on FRC is limited not by the cylinder, but by the solenoid ⅛” NPT port diameter and maximum Cv of 0.32

You can use solenoids in parallel to mitigate this somewhat, but other fittings and line losses limit what you can achieve.

A CIM has a maximum power of 337 watts, but this can be sustained only briefly, not the entire match.




What Ether said, though IIRC it's the internal valve diameter that severely limits flow through a solenoid, and I can't remember the dimensions off-hand. And yes, a CIM cannot be run full-power for an entire match (probably not more than once, anyway), though 4 Cims could likely be run at an average of 1/4 power (maybe more?) for a whole match. This would be an interesting experiment.

Back to the math...

I assume you are referring to using pneumatics in a reciprocating-piston setup, in which case you can calculate a theoretical power output using ideal Otto cycle calculations, where your volume values are computed by geometry, and your pressure values are determined from approximate flow rates through the supplying solenoid(s).

Edit: it won't be exactly like an Otto-cycle calculation, but it will be close, you'll be integrating work done in a PV chart.

[JesseK]

The pneumatic cyllinder feasibility problem appeared simpler to me when I thought about it a few months ago. Simply add it in as a "turbo boost" to an existing drive train via a 1-way clutch or paulet system. Linking the two rear drive train axles together with 1 shaft (or 2 shafts + differential) would easily allow for this functionality.

Once implemented, we can analyze the weight: it's about ~15lbs extra, just for a brief turbo boost once or twice in a match. YMMV, but it wasn't worth it for me to investigate further.

[Jared Russell]

If you're hung up on the idea of a pneumatic drive (store energy, then expel it all in one forceful lunge forward), you could accomplish the same thing by using a far more efficient motor, like a CIM, to compress a spring or gas spring (like many kickers did this year).

[Trent B]

Hehe, I suppose it is a little semantic, but there is a lot to be said for using precise and correct language, especially in the field of engineering.

I know the correct usage of power, the problem is so many people don't so for the average person it seems to have a tendency to have qualities of semantics. Gotta love common english language and its distortion of terms to mean other things.

[JamesCH95]

I know the correct usage of power, the problem is so many people don't so for the average person it seems to have a tendency to have qualities of semantics. Gotta love common english language and its distortion of terms to mean other things.

If you know how to use it properly then do not perpetuate its misuse! That is how common English screws things up.

[Trent B]

I use it correctly, 2 years of physics does that to someone :D

There are also always the crazy drivetrains where CIMs and Fisher Price motors are all connected together through a gearbox using planetary gearboxes or some other method to constrain the FP output to the same as a CIMs output RPM. As far as I can tell that would probably be the most powerful setup you could get. Though you would have to rely on Densos, Pneumatics and Globes (if they brought them back) for other components of your drive train.

[Mageofdancingdr]

The pneumatic cyllinder feasibility problem appeared simpler to me when I thought about it a few months ago. Simply add it in as a "turbo boost" to an existing drive train via a 1-way clutch or paulet system. Linking the two rear drive train axles together with 1 shaft (or 2 shafts + differential) would easily allow for this functionality.

Once implemented, we can analyze the weight: it's about ~15lbs extra, just for a brief turbo boost once or twice in a match. YMMV, but it wasn't worth it for me to investigate further.

well, this is what preliminary discussions (me and my friends talking at lunch) usually boiled down to, so if it doesn't seem feasible it's okay being dropped. Plus, I'm the programmer, so I'll just make up the innovative edge on our robot with sensors and functions.

[Ether]

3.1415926535897932384626433832

3.1415926535897932384626433833 :)

[JesseK]

Understanding it's still a whacky thought for potentially great innovation (weight aside), the process of implementing it is invaluable. It's probably best done in the offseason though so your competitions have less chance for failure.

Another idea to link a 'turbo boost' to an existing drive train would be feasible if the drive train implemented a car-style setup with a differential that is driven by a hybrid planetary gearbox. By 'hybrid' I mean that there is 1 output and 2 inputs to the planetary gearbox, much like what is seen in hybrid cars (http://auto.howstuffworks.com/hybrid-car7.htm).

This would eliminate the need for a shifting transmission since the 'turbo' gives the extra power. It may also free up CIMs for use in other systems because an alternative power source is available for the drive train. Depending on the team, that may be worth it even during competition season.

[gblake]

How about if pneumatics are used to drive a large plate full of small spikes into the carpet under/beside the robot and consequently either keep the robot from being pushed out of position, or "inexorably" move it forward by out-pushing another robot. The large plate(s) plus the many, many small spikes are a way to get more "friction" than is available from gravity pulling wheels into the carpet.

The plate has to be large enough to spread the force over enough carpet to avoid damaging a FIRST FRC field. The spikes have to be numerous enough and small enough to avoid damaging an FRC field.

The lateral/pushing force generated/resisted has to be high enough to be useful (at the moment IDK what that value would be).

Instead of trying to use pneumatics to set the plate(s) and move the bot, the mechanism could perhaps rely on a high-torque motor (the pneumatics set/lift the plate. The motor moves the robot relative to the plate.).

Two plates could be alternated to move any given distance (at some slow-ish speed) by putting one down, then moving the max distance possible using one plate, then putting the second plate down and transferring the forces onto it, then picking the first plate up.... Lather, rinse, repeat.

Of course if the FRC game in question (Overdrive, for example) doesn't encourage pushing contests - Never mind. :)

Blake

[AdamHeard]

Understanding it's still a whacky thought for potentially great innovation (weight aside), the process of implementing it is invaluable. It's probably best done in the offseason though so your competitions have less chance for failure.

Another idea to link a 'turbo boost' to an existing drive train would be feasible if the drive train implemented a car-style setup with a differential that is driven by a hybrid planetary gearbox. By 'hybrid' I mean that there is 1 output and 2 inputs to the planetary gearbox, much like what is seen in hybrid cars (http://auto.howstuffworks.com/hybrid-car7.htm).

This would eliminate the need for a shifting transmission since the 'turbo' gives the extra power. It may also free up CIMs for use in other systems because an alternative power source is available for the drive train. Depending on the team, that may be worth it even during competition season.


Another possibly simpler mechanism is the clutch used on nitro and gas Rc cars.

A hollow round (called hte clutch bell) has a gear that drives the gearbox, inside the hollow round is a device driven by the motor with clutch pads sprung loaded in. As the rotational speed of the motor increases, centripidal force causes the clutch pads to move outward and engage the clutch bell. Solves the direction issue, and could be done with COTS components, many larger cars certainly put out more power and torque than a CIM.

This would be better suitted for adding in hte 5th CIM to the drive.

With all that said, I believe a boost is a poor choice to just adding more motors to drive. And with that said, I believe adding more motors in drive is a poor choice compared to adding shifters ;).

[Joe Ross]

Two plates could be alternated to move any given distance (at some slow-ish speed) by putting one down, then moving the max distance possible using one plate, then putting the second plate down and transferring the forces onto it, then picking the first plate up.... Lather, rinse, repeat.

Such a robot is the reason for most of the current traction rules. Team 71 in 2002 (http://www.youtube.com/watch?v=lAmAnkYDUQM). Another video with a few shots of the walking (http://www.youtube.com/watch?v=h4slvnvPHW8&feature=related). Picture (http://www.firstrobotics.uwaterloo.ca/resources/galleries/drivetrains/drivetrains007.jpg)

<R08> ROBOT wheels, tracks, and other parts intended to provide traction on the carpet may be purchased or fabricated (“traction devices” include all parts of the ROBOT that are designed to transmit any propulsive and/or braking forces between the ROBOT and the FIELD). In no case will traction devices that damage the carpet or other playing surfaces be permitted. Traction devices shall not have surface features such as metal, sandpaper, hard plastic studs, cleats, or other attachments. Anchors (i.e. devices that are deployed/used to keep one’s ROBOT in one place and prevent if from being moved by another ROBOT) shall not use metal in contact with the carpet to “stay put.” Gaining traction by using adhesives or Velcro-like fastener material is not allowed.

[gblake]

Such a robot is the reason for most of the current traction rules. Team 71 in 2002 (http://www.youtube.com/watch?v=lAmAnkYDUQM). Another video with a few shots of the walking (http://www.youtube.com/watch?v=h4slvnvPHW8&feature=related). Picture (http://www.firstrobotics.uwaterloo.ca/resources/galleries/drivetrains/drivetrains007.jpg)Thanks - Apparently it's been too long since I last read the FRC rules end to end.

[Katie_UPS]

How big of wheels? we had 12" this year and i think 107(maybe a different team I'm going off memory) had the same ones too.

Remember the Big wheel trikes that were cool in the 90s? Something like that. :D