Re: Best Drivetrain
 

Team 45 prototyped such a design a few years ago. I'll see if I can find it.

[edit] Tom beat me to it.

Re: Best Drivetrain
 

Team 45's ball drive
http://www.chiefdelphi.com/media/photos/15197

Re: Best Drivetrain
 

That's a really neat drivetrain. It's interesting because this is much different from all of my ideas I've had so far. I turned my thoughts away from doing it like this because I always imagined the ball would slip around or would be too smooth to control. It's nice to see an effective way to use balls instead of wheels.

But are there any designs which are effective using only balls and no wheels? That's what I'm going for.

Re: Best Drivetrain
 

Not that I know of, however, it could be done given enough motors. I think the reason is, not enough decent motors. You need 2 per wheel, and that means 8 motors. Yeah, we have that many. No, they aren't all what we'd want for that. We'd need 4 CIMs, 2 FPs, and 2 globes. Not enough decent motors left to put much on top of the drive, unless pneumatics are used for an arm. (Banebots, window, and maybe van door are left.)

Re: Best Drivetrain
 

Actually pretty much all of my designs require 5 or less motors. One for each ball and one to change the direction all of the balls spin.

My newest design requires as few as 2 motors, but it would be extremely impractical with only 2. It would require 3 or 5 to work well. I'm sorry I can't really describe it, but I'm only willing to explain once I get the design done in solidworks.

Another thing I need to work out is how I can hold the balls in place so they're held loose enough to rotate freely, but it would be impossible for them to come out of it's casing without taking it apart.

Re: Best Drivetrain
 

I think that's what we call a crab drive.:p

I think the main reason that ball drives aren't more popular is that there are swerve, crab, omni, and mecanum drives to choose from, some of which are simpler and some of which are more complex to plan and easier to build.

Re: Best Drivetrain
 

Actually, yea, it is pretty much crab drive... but it still would like pretty:cool:

But my latest design is far different from what I originally intended to do. My first designs involved using a sort of gear like wheel above the ball which would be attached to the motor. The gear would run along the top of the ball and on the poles there would be a turning mechanism where you could stop moving the ball and turn in another direction. The wheel above would rest on a turning device which would be controlled by controlled by the 5th motor.

Now I received criticism from my mentors that it would be too difficult to land on the exact tooth to have it turn. It would also be a slow job if it were possible since you would need to slow the motor down so it COULD stop when it needs to.

So instead of teeth the wheel on top of the ball would have bumps on it and on the sphere it would have sorts of crators. The bumbs would fit into it and because it would fit loosely inside you can stop at anytime and turn when you need to.

But yet again I'm rethinking the design. The whole point of what I'm designing is to make a drive train that is extremely menuverable and controllable which at the same time obtain a fast speed. Rolling it from the top like a normal gear doesn't sound like it could reach the highest speeds and having to stop the robot to move again everytime would make it even slower.

That's what I'm trying to solve and I think my latest idea might be an improvement compared to my original ones.

Re: Best Drivetrain
 

This comment got me thinking...
There's already been an idea posted to implement a ball drive in a similar fashion to a crab, but there are boundless other motor possibilities.
Once I have some free time I might try and run some vector calculations and see what I can come up with. Even toying around with the idea in my head I can think of a couple relatively simple ways to control the drive with 4 (or fewer) motors, in a very similar fashion to a holonomic system. The question then becomes to you gain any advantages over a holonomic system, and that's where I'd need to run a few calculations to see if this configuration could allow for any new types of movement (my suspicion is no), or more efficient movements in any direction.

Re: Best Drivetrain
 

I doubt you will find any advantage, besides the cool factor!

I think it would be neat to make a holo-ball drive!

(Thats also what I was thinking reading the other posts before you Larvey)

Re: Best Drivetrain
 

Great... I guess I now know how to find engineers/engineers-in-training. As in, give them a challenge.

I've done a little thinking and it could be pretty fun to try a coaxial crab on top of the balls. Then again, why not just put it on the floor?

Re: Best Drivetrain
 

I think 45 beat you to the punch on that.

Re: Best Drivetrain
 

That's the drive type we've been discussing today...

Re: Best Drivetrain
 

Well, with a ball drive system it would be kind of like having crab drive. I imagine it to be slightly better than crab drive. I know this can't be proven until an effective ball drive robot is made (only balls are used to drive the robot), but I suspect that since rolling a ball in any direction seems kind of more "natural" for a ball to do while rotating wheels around to drive in another direction doesn't seem so much so it sounds to me it's possible ball drive could potential perform better than crab drive. Like I said I can't prove this, but it's worth putting it to the test in my opinion. You can't stop trying to look for other ways to do things, or that really defeats the whole purpose of inovation.

Re: Best Drivetrain
 

you might have a little more manuverability with balls but I can see less pushing power as a sarcafice. I still think it would be mega cool to do. You would have to think of the balls material very careful and find the best balance of grip and slip lol.

Re: Best Drivetrain
 

Has anyone here taken apart a Dyson ball vacuum cleaner? I wonder if the innards of that ball drive could be retrofitted with an FRC kit motor?