A new drivetrain Idea?
 

OK here it is: it is a regular four or six wheel drive, except that each side of the drive train (the blue parts) would splay out to allow driving in arcs. Depending on what angle you expanded them to, you would drive in a larger or smaller arc; If you expanded them to 45*angle, you would travel in a mid-sized arc, and if you expanded them to an 87* angle, you would travel in a very large arc.
There would be a platform suspended on casters between the sets of wheels (the red part) for mounting any mechanisms that you needed to.
The top "diagram" would be fully closed, which would allow you to drive normally; and the bottom one would be fully open, which would allow you to drive sideways.

Am I missing anything that would make this not work?

P.S. I apologize for using paint, It's all I have at the moment. :)

Re: A new drivetrain Idea?
 

Wouldn't the casters drag on the floor/carpet while you are moving sideways?

Oh yea and how are you going to program that thing to go sideways? when hinges are closed it can go forward and backward but when you open the hinges and wheels are 180 degrees, wouldn't each side try to fight against each other?

Re: A new drivetrain Idea?
 

Hmm very interesting. very cool idea. i am inspired yet faced with a complex and perhaps frivolous challenge without much rewards as far as a competitive drive train None the less. as such i post the question in what situation fanciful, practical or otherwise do you see this machine being an advantage? once you have come up with an answer that satisfies your curiosity and overcomes any laziness you may or may not have incurred through your youth to design such things. bring your design to life through a drawing, a model, an animation , a cad drawing, whatever and then use that to assess and further your creativity. I relay like this idea and i think its relay cool. i have some ideas of variations that could be made to make it simpler and more controllable but and I'm shure you will come up with some too. Please let me see this as a beginning of a new robot designer. they're aren't many people that can come up with and fabricate unique ideas and innovations like that.

Re: A new drivetrain Idea?
 

One thing that I thought it would be useful for was driving around a centralized location.

Take the 2006 game for example. If you had a robot that could drive in arcs and keep itself aimed at the goal based on how large the arcs were, that would be quite an advantage.

Re: A new drivetrain Idea?
 

I'm having trouble convincing myself this would work. Specifically, the omnis are blowing my mind at this point. I know the theory behind them is always that they sideslip to make turning super easy, but they also end up getting pushed side to side. The one arrangement I can sort of envision is when your hinges are at 45 deg and the sides are now perpendicular to each other. If just one side moves, the opposite side will side-slip and it'd end up going that direction. So I'm skeptical it'd do exactly what you think it will in that arrangement, and thus I'm not entirely certain about any other arrangement.

It's still an interesting design, though.

Re: A new drivetrain Idea?
 

I don't believe that the casters would cause a noticeable amount of friction.

Now, for programming it to go sideways, you could just program it with tank drive and make the x-axis on the joysticks move the robot side to side when it is open.

Re: A new drivetrain Idea?
 

Hmm...The omnis were originally just so that you could open and close the sides without an extremely strong motor. If you replaced them with grippy wheels, it would just take a lot more power to pull the wheels sideways when opening or closing the wheel-base.

Re: A new drivetrain Idea?
 

Very interesting idea. Keep going. There are many problems you will face while designing this but everything has a solution.

Re: A new drivetrain Idea?
 

I was thinking grippies just at the middle or closest to the hinge. It would certainly do exactly what you want with a single grippy on each side.

Re: A new drivetrain Idea?
 

I think this is a great idea for any time it is my opponent. I think it will get pushed all over the place by the other robots with tank style drivetrains. But an innovative idea nonetheless. :)

Re: A new drivetrain Idea?
 

Just an idea, if you replaiced the omni wheels with mecanums, wouldn't you be able to move back and forth as well as side to side?


Edit-Took the idea and ran with it. I love Rhino 3d

Re: A new drivetrain Idea?
 

Mechanums would theoretically give you full range of manueverabilty even with the wings fully swung out, albeit with reduced speed in most directions. I must admit that the code for mixing a joystick signal to appropriate motor signals at any amount of swing out would be a headache I wouldn't look forward to, but you would have just about the coolest drivetrain around if you pulled it off well.

Re: A new drivetrain Idea?
 

OKay, I see one glaring problem. What's stopping another robot from planting itself next to you and stopping you from opening up your "wings?" I mean, that would be a good defensive strategy against a robot of that nature.

There was a robot, I think it was 930 in 2005 that opened up like this but I'm pretty sure it was for a different reason.

Also, how much do you think this set-up, as you have it now, base only, would weigh? Looks pretty heavy.

But nonetheless it's a very interesting idea. I'd like to see it a bit more.

/Edit: If you used a two-wheel crab drive, wouldn't you just be able to turn the crab and that would open itself up? Turn the wheels to X degree and drive the wheels. This would cut down on some weight I think and just hinge the wings. And then you should be able to move side to side, in an arc, and forward/backward with less weight than the mecanum.

Re: A new drivetrain Idea?
 

Based on the drawings I've seen in this thread, isn't this type of design going to violate rule <R08>

"...In other words, after the start of the match the robot may expand up to a maximum volume of 60 inches by 60 inches by 60 inches."

Granted, this was a specific rule for 2006, but you have to keep such rules in mind for future designs. And now to comment on the design, I'm not quite sure how this is an advantage or improvement over a crab or mechanum design. It seems much more complex to make a completely hinged system.

BEN

Re: A new drivetrain Idea?
 

Only if they used the largest possible starting dimensions. If they chose to start as a 28X28 square they should have enough slop to make this work w/in the 2006 rules.

Re: A new drivetrain Idea?
 

I was thinking the same thing. However, What if the "hinges" were in opposite corners, the center of each side, or even if there were more than two hinges? While I, too, would wonder if the complexity gives you a distinct advantage over other designs, this is certainly inventive and interesting.

Re: A new drivetrain Idea?
 

It would be interesting to see a robot with two sets of these, effectiving spreading your drive wheels to a wider and longer wheel base when open

and changing the 'front' of the robot by 90º

Re: A new drivetrain Idea?
 

In 2005, 648's robot could extend to give it more stability. I don't remember the exact stats but it almost doubled it's short side. How we got it to do this was just lock the back wheel and power the front two wheels and then it would lock into place with servo actuated hooks. When we when back to get into the box all we would have to do was lift the hooks with the servos and squish back together.

This concept made me immediately think of that robot.

Re: A new drivetrain Idea?
 

I personally think that it is a very innovative idea which can amaze some people if properly designed and built. This design doesn't have to be used particularly for a FIRST robot, but can be used for demos and offseason projects.

As far as the rule <R08> goes (after the start of the match the robot may expand up to a maximum volume of 60 inches by 60 inches by 60 inches)... there have been teams who have made their base shorter than 38x28 (bot had riggers and so forth but after full extension they were in the size limit). The problem Ben pointed out earlier is one of the very important component of this design (if you are building this chassis for a FIRST robot according to last year's rule) but there are ways to avoid the chassis extending more than 60". I do agree with you Ben where you said it's a very complex design, but how cool would it be to see something like this on a FIRST field.

... keep going Cody, show us your next step to this design.

p.s. - I am still waiting to hear from Baker, Neun, and Copioli about what they think about this design.

Re: A new drivetrain Idea?
 

I'm not trying to crash your idea but I think that it would have to be thought out just a little bit better. I am a fan of creating new drive systems. It would be hard to convince me that this would work, and what are the advamtages to having this over a typical swerve drive? :)

Re: A new drivetrain Idea?
 

Well that's interesting!

If you had a particular design problem you were trying to solve, I'd say you might want to open it up to other possible solutions. But it SEEMS like you are floating an idea to see what other people thing - which is great! Being creative for creative's sake is great - you don't always need to be engineering a solution to a problem.

Let's say this never becomes a FIRST robot drivetrain - I bet it still gives you ideas on some other FIRST mechanism. Or - it made me think of this... an unpowered cart to carry stuff (maybe a FIRST robot) that folds up for easy shipment and storage in the pit. BAMN - already a use for FIRST.

Thanks for sharing!

Re: A new drivetrain Idea?
 

While Creating concepts for the unknown Rules of the FUTURE. One can not limit themselves to the rules of the PAST.

Clearly Cody thought of this as a pure elemental idea not tied to any competition robot team competition or set of rules. it is simply an idea. I say go for it Cody. don't worry about any rules, you don't have any. just make it up as you go along and just Tailor your ideas to your needs when you chose to pull it out of your arsenal and use it

Re: A new drivetrain Idea?
 

one possible applicaiton of this winged-drive train idea

in several seasons we had to pick up objects/balls from the floor. Making a robot that is open on one side leves it vulnerable (you cant have an opening and a bumper at the same location) and you have a tradeoff between the footprint of the robot, and the max possible size of the opening

but if your drive train swung out into a wider footprint (on all four sides) you could have a significant advantage

plus, after you collect objects from the floor, you could close up again, to make the robot more robust, and compact, if there was an advantage to that configuration.

Re: A new drivetrain Idea?
 

hey, fin
What about a ball caster? They reduce the movement that a normal caster has. Page 1224 of Mcmaster Carr is a threaded stem ball caster.

Re: A new drivetrain Idea?
 

Team 108 used them back in 2005, I didn't like them too much because that robot was used on the field as well as outside to do programming. All the sand and stuff from the carpet got stuck with the ball and later on the ball started to get jammed. Mike, I thought you knew me better, I don't like to use casters.

Re: A new drivetrain Idea?
 

I love that Idea with mecacums.


Imagine this scenario. There is a similar style goal with a light that you use the camera to track. You open up to the right angle based on the distance you calculate from the camera, and the robot squares of for you. All you do is hit left and right on the joystick to move in an arc around the goal. If you move forward or back the robot will adjust the angle and square off again, pretty much guarunteeing a perfect arc around the goal. Also, you would have the ability to drive in all directions normally.

I wish I could convince my team to try this :/. But I can barely get anyone to listen to my idea of doing team 25's wheels.

Keep it up, I'm really interested now.

Re: A new drivetrain Idea?
 

all castors can pivot or roll in any direction. Thats what a castor is.

If it cant go sideways, its called a wheel! [ºiº]

Re: A new drivetrain Idea?
 

This may be true, but a ball caster doesn't have to pivot before it can roll (something we found out the hard way when our autonomous kept just missing the mark in 2004). It's just one less thing to have to worry about in programming; we've had enough to worry about this year!

Re: A new drivetrain Idea?
 

There is really no need to create such a complex drive system. It would create so many more problems in the weight catagory as well as for your team programer. Another problem is during a match your robot will be extremely voulnerable to be redirected and trapped. If anpohert teams robot is next to yours while you are switching modes your robot will be spun around using its own power from the motors opening then closing the hindge. If your in the open possition and something gets into your robot while your closing it will jam up your robot and make you waste preciouse time to fix the problem. If you are looking for high manuverabiliy then i suggest using mechanum wheels.

Re: A new drivetrain Idea?
 

Are you talking about the design that uses omni wheels, or the 4 wheel mecacum design? The 4 wheel mecacum design seems better because it will always be omnidirectional and still be able to travel in an arc.

Imagine: Locking onto a goal, facing it, adjusting to the right arc angle. Then hit left/right on the stick to travel on the arc. Hit forward or back to move closer (mecacums remember) or farther, the angle readjust automatically. You can juke forward, back, left and right instantly without looking away from the goal. I doubt next years game will have the same situation though :/

Re: A new drivetrain Idea?
 

How about instead of using casters, which can be a little problematic as people have mentioned above, use plastic nubs. We used them on our robot, as you can see in this
photo. They slide really easily and you don't have to worry about them ever getting stuck.

Re: A new drivetrain Idea?
 

The more I think about this idea, the more I wish I had more Vex omnis. It would be easy to prototype on Vex. Anyone got 6 omnis?

Re: A new drivetrain Idea?
 

(I'm quoting Kevin as a starting point, not because he's wrong. He's not.)

The idea is that the chassis will rotate about the point where lines, drawn perpendicular to and from the center wheel on each side, intersect. This is true of how traditional tank-steer robots operate as well, except that they typically lack the ability to move that point as this design allows.

Typical drives can spin in place because, by moving each side opposite the other, the translation vector of each -- that is, the force that would move it forward or backward -- is cancelled by the other. When each side is no longer parallel with the other, some of that translation escapes, as it were, and the chassis starts to behave as an inefficient holonomic platform. Thus, running each side in the 'opposite' direction will result in sideways translation. Driving them in the same direction will result in forward or backward movement. The only exception would be when they sides are again parallel, but collinear, as would occur when opened 90*. In this instance, driving them in opposite directions would do nothing at all (except break your robot, perhaps), while driving them together would result in the most efficient sideways translation possible because you've effectively changed which direction represents 'forward'.

Without a fixed point about which to rotate, all this design seemingly allows is a way to vary the efficiency at which a holonomic platform operates. That's not without merit, necessarily, but it doesn't seem to me that it would work as advertised. All of this assumes, of course, that it uses omniwheels. Other wheels would effectively function the same, but it would be even less efficient.

Re: A new drivetrain Idea?
 

Here is a thought starter;

Imagine a traditional mechanum drive arrangement. Now imagine it translating sideways, except that the rotational velocity of the front 2 wheels is less than the rotational velocity of the rear 2 wheels. Wouldn't it have exactly the same motion that your trying to get?

Re: A new drivetrain Idea?
 

I see one big flaw in it... when the bot is extended out for side-to-side motion (Crabbing) it is totally vulnerable to being pushed back and forth because of the omni-directional wheels. I think the drive train design, while pretty cool and original, would be so poor defensively that it would be almost useless in a FIRST game.

Maybe another application could be in order? It would be cool if you could use it in an off-road vehicle so it could snake through obstacles. Modification would be needed, but it has potential.

Re: A new drivetrain Idea?
 

Plastic Nubs are simple and pretty slick, but they make driving the bot a little harder and there is the small chance that you'll tear something on the field or snap one off.

I like doing teflon "scrub" wheels. They are mounted inline with tank-style wheels and give it good stability driving in a stright line, but slip when you're turning.

Re: A new drivetrain Idea?
 

I agree with James. While the drivetrain has potential for outside uses, if you look at the way defense has been coming back to FIRST, it would be pretty much useless, due to easily being pushed, and the great possibility of jamming the system.

Re: A new drivetrain Idea?
 

But if you use mecanums in a 4 wheel drive like above, that is greatly diminished.

Re: A new drivetrain Idea?
 

I agree with what has been said a few times, that an idea along these lines might be cool for non-FIRST purposes. But for FIRST, I think it invests too much weight, spaces, motors, and compelxity (especially for either the driver and/or programming). Secondly, it would do as Madison suggested, and perform similar to a holonomic system (which could be beneficial in other ways).
There are other ways that your desired arc could be achived. The mecanum suggestion earlier is one.
Another could be a standard holonomic drive.

By moving the wheels as such (with the "NW" and "SE" wheels driving at different rates) you can acheived the desired arc motion.

Re: A new drivetrain Idea?
 

There are few posts in this thread that just explains how this idea would never work and how other kind of drive trains will work better (basically asking him to give up on this). I think that is pretty obvious that this design is in the very early stage, and it definitely has some potentials. Has any of you seen a drive train like this before? Team 47, Chiefdelphi designed the first swerve drive and over the years teams have come up with stronger swerve drive. I bet one of the robots could have pushed around chiefdelphi's first swerve drive easily at that point but it has been developed and modified by many teams over the years. Rather than telling Cody that this idea would never work, why not help him and give him ideas about how to make this new idea a reality?

Are there people here who wants to think outside the box and come up with new designs that has never been done in FIRST?

Keep in mind the first transmission I ever designed weighed 13 pounds, the second one I designed weight weighed 5 pounds. Designs can be reviewed and modified for the better. I am going to propose to all the chiefdelphi designers to come out here and post how can this design become a product. Thank you.

Re: A new drivetrain Idea?
 

cromat44 is exactly right about the kind of advantage I was originally looking for, although some people have mentioned a couple of others that are now seeming VERY interesting to me. Please don't take the drawing with the omni-wheels as set in stone... because as Arefin or Tytus have said, It is more a way to get my Idea across than an actual design. I'm taking into consideration everything that everyone is saying, and I just don't get how this wouldn't work. When coming up with this Idea, I was mainly thinking of roller blades or Ice skates, and how the athletes that wear them turn in arcs; it seems to work for them... I will try and build a prototype tomorrow or the next day. Until I can do that, please continue as you are.... I find this VERY helpful :D


P.S. Sorry if I don't have the Prototype tomorrow, I have to go to a wedding.
P.P.S. Thanks Arefin and Tytus:D

Re: A new drivetrain Idea?
 

This is fascinating. Any idea on how you would wire it?

Re: A new drivetrain Idea?
 

Oh! I see what you are saying.

That would be a very fun demo bot based on what you have designed so far.

But do the wings need to be so massive?

Imagine a robot with 4 wheels. Rear wheels remain parallel to the sides of the chassis, and the front two are independantly rotated, and all four are independantly driven. You could achieve the same effect without dealing with bumper zones and appendages and all that stuff. Also, you wouldn't be pushed forward and backward so easily.

Also, looking at what cromat44 said. This would be incredible, however I remember watching a video team 88 made with a holonomic robot that did the same thing using a gyro and a holonomic drive. I'm not a programmer so I have no idea how it worked, but that's how they described it.

I forget where I saw the video though...

Re: A new drivetrain Idea?
 

I was planning on making a prototype of this as well. It will be posted in a month or so because I need to get some stuff from vexlabs and make some mecanums (I made ona while back similar to the "vexanum" wheel posted a while ago). Hopefully I can help you prove this design useful for this kind of game.

Re: A new drivetrain Idea?
 

I remember that video.

This could be done on the software side of things, BUT it would give your programmer a headache, and you would have to do some R&D before and during the season. Basically, it'll take a while to troubleshoot all of the kinks out of the system.

Re: A new drivetrain Idea?
 

That would be cool. Whith programming any holomonic or mecanum drive could drive the way i was saying and stay locked on. That's a good point. the question is wether or not the wings would improve that feature. Time will tell with prototypes :rolleyes:.

Re: A new drivetrain Idea?
 

While the wings might improve that feature, you would have to weigh that improvement against the fact that with more moving parts and openings, the mechanical solution might be more prone to failure, as opposed to a software solution.

Re: A new drivetrain Idea?
 

The reason I don't beleive the design, as you have presented it so far, would not achieve the desired result is that it doesn't work like the skates you envisioned. In the example below, if you drive each "wing" at equal value, the resultant vector would be 45º between the two.

I think a design like yours could be acheived, and do some exciting things, but the way you have it currently wouln't work sucessfully.

Re: A new drivetrain Idea?
 

If either(but not both) of the pods had the drive direction reversed, it would turn in an arc.

Re: A new drivetrain Idea?
 

No, it wouldn't. The resultant vector would be pointing 45* into a different quadrant is all. Reverse one of the arrows Sean drew and do the vector addition again and you'll see that, without a fixed point about which to rotate, this is nothing more than one half of a typical holonomic platform. If y'all were to build this and it did travel in some sort of arc, the only likely reason for that to happen is because of inequalities in the operation of each side of the drive. The efficiences losses won't be exactly equal, so there's some chance that, given equal power, the component vector of each drive side would be slightly different.

Re: A new drivetrain Idea?
 

What if you didn't use omniwheels?

Re: A new drivetrain Idea?
 

I've decided I don't buy this. If figuring this out were as simple as adding the force vectors like you and Sean do, then I'm forced to conclude that a standard 4WD omniwheel setup can't turn. If I do your style of vector math when I drive one side forward and the other side back, I get zero and the thing doesn't move. This is patently false.

"Where's the problem, then?" you ask. Well, the forces aren't being applied through the center of mass of the robot. As this is the case, you should end up with a residual torque that will turn the robot as it translates to the side. Viola! You get an arc. However, the centerpoint won't be wherever some perpindiculars from the sides intersect. It'd depend on the center of mass of the robot, and probably a host of other factors. So, even more confusingly, it would change slightly if the CoM of your robot changed from, say, emptying a hopper full of balls.

There, I went and thought about the physics of this. On a weekend no less. I hope y'all are proud of yourselves.

Re: A new drivetrain Idea?
 

That's right. The center of gravity would represent the fixed point of rotation. Holonomic platforms have two more drive sections and those cancel the torque applied to the robot's center of mass when driving in a straight line. Because this design is asymmetric with respect to that center of mass, it will apply some torque and travel in an arc. Opening or closing the wings, however, will not vary the radius of that arc any more than it moves the center of mass along a line that bisects the angle between the wings. The drivetrain ought not represent more than, say, 15% of the robot's weight as far as I'm concerned, so you wouldn't likely see a notable shift in the center of mass.

While I certainly don't want to rain on anyone's parade and I think it's valuable for students to be entertaining and developing interesting ideas, it's also as important for them to understand what's happening to make them work and to understand the similarities between their ideas and existing technologies. It's not always fun to use what's already available (and I often don't), but sometimes doing an effective cost-benefit analysis is as valuable as implementing a new spin on an old idea.

It seems to me like Cody's been trying to examine the function of technologies like holonomic, mecanum and swerve platforms and distill from those the bare necessities that make them work. That's an awesome goal and, while there certainly are some really bloated examples of these designs, there are equally as many with important, functional features that aren't apparently obvious at first examination. Starting a design with the minimum functionality desired and working through its problems is a fantastic way of seeing how and why others have added in certain features.

Re: A new drivetrain Idea?
 

I'm slightly disturbed about the amount of half-truths being purveyed in this thread. I suggest that before making assumptions about the type of motion that a given drivetrain can achieve, you should follow Kevin's lead and review the basic kinematics and vector mathematics that goes into the actual calculations. As aspiring engineers, you should be moving past the "I think this will work this way because I think it will" and moving on to "I know this will work this way, because I've done the calculations to back it up".

For those of you who have yet to learn about these types of calculations, here are some great resources:

http://en.wikipedia.org/wiki/Vector_%28spatial%29
http://en.wikipedia.org/wiki/Kinematics

Once you've gotten a handle on those, take a look at Ian's whitepaper which discusses the calculations behind omni-directional drive systems:

http://www.chiefdelphi.com/media/papers/download/1855

With a firm background in linear algebra and kinematics, you'll find that questions like one's being posed about the arc like path, become simple and intuitive. Now, by no means is anyone expected to learn this over night, but I see a lot of energy and enthusiasm in this thread, and I have a feeling that a lot of you can digest this stuff on your own.

Remember, being an engineer isn't just about messing around in CAD.

Re: A new drivetrain Idea?
 

I probably wasn't clear enough, as I was in a rush at the time I posted.

At 90 degrees it would turn in an arc, but a very tight one, centered around roughly the same point(the pods not being at the same distance from the effective corner will cause it to not be quite perfect, I think)

The wider the angle between the pods, the larger the arc would be.

One thing that may aid in controlling the arc is a 3rd/5th motor(depending on the design) in the front as the other point of contact. Controlling the speed and direction of the extra wheel should give you precise control of the length and shape of the arc.

Re: A new drivetrain Idea?
 

I've been reading this thread lately, and it's made me quite happy. I personally believe that drive trains are often overlooked when it comes to innovation and creativity, even though they have the ability to make or break a robot. I've been spending a lot of time this off season on designing different DTs (although I'm one of the end-effector/manipulator/shooter guys), so you can understand why I'm excited to see a completely unique idea come around. A new drive train like this, whether or not it has a useful application or if it's ever used, can be used to inspire fellow DT engineers/designers to be a little more creative, possibly resulting in more efficient, exciting drive trains. So basically, I'm congratulating you for thinking outside the box and bringing innovation about for the sake of innovating. I really look forward to seeing how your prototypes work. Good luck and try to get some video! Haha.