Re: Truly omnidirectional omniwheels?
 

Not likely gonna need a patent for those hemispherical wheels we were working on them this summer: http://www.chiefdelphi.com/forums/sh...ad.php?t=40770 but take a look at what we came up with its a cool design

Re: Truly omnidirectional omniwheels?
 

I don't think you guys are understanding my point... I know about the other omnidirectional drives(thanks for the links, however, I like information). My point is a way to make other omnidirectional drive trains by using another design of omniwheel. That... was my intended purpose for the topic, to ask whether another kind of omniwheel could be made that was more... well, omni. I know that all the other drives are successful, but those innovation awards are really appealing, and I think that another omnidirectional drive train could be made with my idea. I've already said it a few times- rotating rollers instead of just the wheels. Basically lets you have the miniwheels have their x axis rotate, with a little modification so that it can't rotate into the same direction as the wheel itself. This would allow there to be traction for the wheel going forward, and allow it to go any other direction without traction. That would allow wheels to face 45 degrees away from each other, , or any other degree, but not oppose each other. That would let there be more drive trains with opposing wheels. Which means more creativity.

Re: Truly omnidirectional omniwheels?
 

What about an omni wheel but instead of having a bunch of wheels around the main one, you just have a bunch of ball bearings stuck into it.

I'm not sure if something like this exists yet, I don't see why it shouldn't.

I see a problem with this though. If you were able to push an omni wheel in any direction, then it wouldn't be able to provide any traction when you rotated it with a motor. It would just spin in place.

Now, someone mentioned something about "the wheels on the bottom of teacher's desks."
I assume that you meant something like these:
http://www.photoflex.com/photoflex/p...300/caster.jpg
Those are called "casters", just for future reference.


EDIT: I just saw something about limiting the casters' rotation as so that they don't allow the wheel to spin in place. Ignore the second paragraph in this post.

Re: Truly omnidirectional omniwheels?
 

Hey, i remember seeing your team at FLR. Where did you get the inspiration for your omni wheels?

I <3 OMNI wheels!

Re: Truly omnidirectional omniwheels?
 

Yeah, casters are what I've been talking about. Although with further thought, I've realized that if you have the rotation limited and the caster needs to move that way because the robot is moving in such a way that it wouldn't spin the other way... might have to do something with springs so that the wheels move to default when off the ground. Of course, ball bearings were my first idea, but then I realized the whole 'robot not moving' thing, so I switched my idea into the (heavily modified)casters plan. Probably not traditional casters, though... might want the axis in the center.

And FLR was awesome. Team 229... can't say as I can recall that one, and you have the 1126 site in your profile. Link me to a pic so I can remember. 1126 was awesome, of course. I remember- you guys CRUSHED the opposition. It was so fun to watch! Your shooter was pretty danged great. We(the Duct Tape Bandits) couldn't say we were spiffed to lose, but we had the six hour bus ride home on the AWESOMEST BUS EVER to make us feel better. Seriously, we had a 42 inch widescreen HDTV, strobe lights, lasers, a fog machine, ceiling mirrors, fiber optics, subwoofers, hardwood flooring, sideways leather seating(with tables and cupholders), those things with the electricity where you touch them and all the electricity is attracted to your hand... it was the greatest bus ever. Most definitely my most fun experience in a while.

Also, the inspiration for the omniwheels came when I was bored enough to try to think of an innovative drivetrain, so I was thinking up a hexagon design, until I realized it wouldn't work with omniwheels because the little wheels wouldn't be facing the proper way, and if you moved them so they faced the right way, they wouldn't be facing the right way for moving other directions. So I decided I'd think of a way to make a better omniwheel that would ACTUALLY be omni, instead of just forward and sideways. This was all at one in the morning, of course... took a nap soon as I got home, woke up at 11, didn't feel like doing homework... all that great stuff. You can think up crazy stuff at one in the morning. Best time for innovation.

...yeah. So, with modded casters(methinks they'd need some reinforcements to hold a hundred pounds of metal moving at high speed- I'm thinking some sort of box protection design with stronger sides for holding the wheel so the axel doesn't break under stress), omniwheels can be made to be MUCH more omnidirectional for weird drive trains like the hex drive train I want to do.

...I need some sort of CAD program for my computer so I can draw this. Or I can use one of my dad's programs. He has Python. Would that work for CAD drawings?

(I'm just posting all this stuff here instead of talking with my team because my team probably wouldn't listen to me-not very popular with people because I have problems censoring myself in conversation and am hyperactive)

All right. More opinions on my(hopefully now clarified) idea?

Re: Truly omnidirectional omniwheels?
 

well, i am no longer on 1126. i stepped up to college this year and am on 229. Clarkson University robotics. The reason why i asked where ya got the inspiration for those wheels, i that i made ones in 04' that looked similar. heres a picture.

also here is a close up of the wheels.


There is more info on www.gosparx.org too

Re: Truly omnidirectional omniwheels?
 

Erm... I'm afraid I can't see the resemblance between those omniwheels and my idea. They look like regular(multicolored) omniwheels to me... what's making them different from the normal kind?

Re: Truly omnidirectional omniwheels?
 

i was stating to the ones made on this years robot of yours.

http://robotphotos.org/v/first/finge..._7564.JPG.html

Re: Truly omnidirectional omniwheels?
 

No, it is not true.

Omniwheels move diagonally just as easily as they move forward. Perhaps more easily, since the motor doesn't need to be turning as quickly. They are called omniwheels because they indeed move omnidirectionally.

Re: Truly omnidirectional omniwheels?
 

Ah, yes. Very similar to our design. Great minds think alike. Unfortunately, I didn't know what an omniwheel was before this year. So I wasn't involved in that aspect... which means I don't get to qualify as a great mind. Curses.

And there are pictures of our robot online? Kickin! Those are some danged good pictures too... although it does give the inherent stalker-ish aspect, considering there's a picture of me in there... ah well.

Re: Truly omnidirectional omniwheels?
 

...I can't visualize omniwheels working perfectly at a 60 degree angle from the direction they're suppose to roll...

Re: Truly omnidirectional omniwheels?
 

When the robot is moving in the direction of rotation, the wheel rotates and the rollers are stationary on their axes. When the robot is moving perpendicular to the direction of rotation, the rollers rotate and the wheel is stationary on its axis. Any vector in between these produces rotation on both the rollers' axes and the wheel's axis.

Re: Truly omnidirectional omniwheels?
 

I don't know about your team, but our motors use an autolocking system so that it's harder for us to be pushed. Thus, whenever a motor isn't receiving instructions, it locks itself up, so if certain motors are moving(say, two matching sides in a hex drivetrain design) while others aren't, the wheels wouldn't be rolling to go along with the miniwheels. Omniwheels wouldn't be very omni in that situation. And that's the point of my idea.

Re: Truly omnidirectional omniwheels?
 

I've messed around with this idea in order to replicate something I saw in a music video.

A company called Animusic ( www.animusic.com ) makes this sweet midi driven animations... I've always wanted to re-create a scene out of one of the animations... so I'm going for the 3 slightly humanoid looking robots on the "Starship Groove" animation... anyhow back to the story...

The spherical track motor works exactly like a linear track motor except for the fact that the micro-electromagnets are arranged within a sphere made of a non-ferrous material. For my design, this sphere would fit into a matching hemisphere, very slightly larger than the sphere. This, in effect creates a fully functional low-load-bearing ball and socket joint.

OK thats the overview, now heres the problems with it:

There would have to be a processor dedicated to each joint. The design requires at least 3 (4 if it is going to be stable) pulse width modulation channels. It would never be FIRST legal since the victor's update rates are over 26 times too slow for updates. The PWM period would most likely be something like 500ns or so, because of the high instability of intersecting lines of magnetic flux. :ahh:

The joint itself would have to be encoded for position somehow, perhaps with a hall cell array or something like that. The updates for the servoed position would have to be done every 500ns to keep up with the pulse train, the high update rate is needed to overcome the problems with the intersecting flux lines.

So in a nutshell, here's how it is:
1. Would have to be based on a DSP running around 100MHz for a clock

2. It will eat TONS of current

3. Has to be run at a very very high voltage if you want to get much speed
or load capacity out of it.

4. Will require one UART for positional data input will need 4 channels
of simultaneous high speed PWM, run through a mux chip of some kind
in order to drive the hundreds of micro-electromagnets inside of the
sphere.

5. Will need a super high speed latch chip in order to retrieve data from all
those hall cells.

6. Driver board will have to have a power transistor or mosfet for every
single electromagnet.

7. All parts within about 6 inches of the thing will have to be non ferrous.

8. And oh yeah, the programming will be extremely hard (servoing in 2
dimensions)

:yikes: Did I lose anyone?

Granted, this is a design which would work for a positional as well as a speed based spherical track motor. But, like I said, my application required positional. It would work for motion purposes as well, though. I'm putting this on my "Things to do before I die" list.

-Q

Re: Truly omnidirectional omniwheels?
 

I originally thought the same thing but I think he means that they wouldn't move if the driveshaft isn't rotating.