Searching For Swerve / Holonomic Drive Idea

[CalTran]

Originally Posted by Michael Niemiec

Yes, this is what I had in mind.

Thank you very much!

Wait seriously? I just like bringing up that robot whenever I (remotely) can, but you're welcome.

[Michael Niemiec]

Yes, now that I see it, It is exactly what we were talking about. I would like to do something with it in the off season maybe. I would not use a kickball like that, but maybe a small steel ball of some sort. It seems easier and less expensive than a full blown swerve module.

[trumpthero786]

Originally Posted by Michael Niemiec

Yes, now that I see it, It is exactly what we were talking about. I would like to do something with it in the off season maybe. I would not use a kickball like that, but maybe a small steel ball of some sort. It seems easier and less expensive than a full blown swerve module.

I feel like steel would be very slippery on carpet. Traction would be difficult. I'm not sure I understand how something like this would function like a Swerve drive. If the balls are not powered, how is this any better than a rear wheel drive, omniwheel drivetrain? It does however look like something that would be a very fun project.

[Michael Niemiec]

Originally Posted by trumpthero786

I feel like steel would be very slippery on carpet. Traction would be difficult. I'm not sure I understand how something like this would function like a Swerve drive. If the balls are not powered, how is this any better than a rear wheel drive, omniwheel drivetrain? It does however look like something that would be a very fun project.

I wonder if a layer of Gaffers tape or similar would help with the traction, because I agree steel would slip. If the traction would work out, it would be like a cheaper swerve drive option. But if the traction problem couldn't be solved, a omniwheel drive would be better.

I think this would be cool to build, but hard to implement but holonomic/ swerve drives intrigue me and I am always trying to think of a new way to do them.

[CalTran]

Originally Posted by trumpthero786

I feel like steel would be very slippery on carpet. Traction would be difficult. I'm not sure I understand how something like this would function like a Swerve drive. If the balls are not powered, how is this any better than a rear wheel drive, omniwheel drivetrain? It does however look like something that would be a very fun project.

Releveant posts about mechanics, but largely it's "simpler" and far cheaper to build than a full swerve drive. Arguably, the effectiveness now a days is questionable, but certainly something worth looking back into since there's work around for it.

[Ether]

Originally Posted by trumpthero786

I feel like steel would be very slippery on carpet. Traction would be difficult.

True.

I'm not sure I understand how something like this would function like a Swerve drive. If the balls are not powered

They look like they are are powered.

But as shown it does not have the same mobility as a swerve*.


*"swerve" meaning independent steering and drive on all wheels.

[lethc]

Originally Posted by Ether

They look like they are are powered.

But as shown it does not have the same mobility as a swerve*.
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Just because there's only two balls, right? If there were four 'ball modules' then it should have the same mobility as a swerve drive from my understanding. Or are there issues with the ball modules that limit their mobility?

[Peyton Yeung]

Having revamped the 2003 ball drive while in high school, the trickiest part about getting it to drive in my opinion is balancing the normal force on the ball by the drive rollers. Too much force and the ball won't move while too little and it won't strafe.

[Alan Anderson]

Originally Posted by Ether

But as shown it does not have the same mobility as a swerve.

I'm trying to figure out what it's missing that makes it not as mobile as a swerve. It can rotate at any time by applying different speeds to the left and right sides, and it can move in any direction at any time by varying the forward/backward and left/right drive motors. Rotating while traveling in a straight line is difficult, but only because it takes a lot of coordination, not because physics keeps it from being possible.

[ctt956]

Originally Posted by Alan Anderson

Rotating while traveling in a straight line is difficult, but only because it takes a lot of coordination, not because physics keeps it from being possible.

I would think rotating while driving straight with any drivetrain would be fairly difficult...

[CalTran]

Originally Posted by ctt956

I would think rotating while driving straight with any drivetrain would be fairly difficult...

1717, 973, 16, and other swerve teams have done it before. It's possible, but as said, requires an absurd amount of coordination.

[Roboshant]

I believe this is a hemispherical omnidirectional gimbaled drive or a HOG drive.

[Ari423]

Originally Posted by Roboshant

I believe this is a hemispherical omnidirectional gimbaled drive or a HOG drive.

No, according to its name a HOG drive uses a tilting hemisphere that spins in one axis (parallel to the hemisphere's circle), whereas these use a full sphere that can spin in 2 axes.

Swerve (and mecanum) technology has progressed a lot since 2003, so today there are much simpler and better ways of making a true omnidirectional drive compared to this pseudo-omnidirectional drive.

[Alan Anderson]

Originally Posted by Ari423

Swerve (and mecanum) technology has progressed a lot since 2003, so today there are much simpler and better ways of making a true omnidirectional drive compared to this pseudo-omnidirectional drive.

I'm still trying to find out what makes people call the ball drive something other than a "true omnidirectional" fully holonomic system.

[Ari423]

Originally Posted by Alan Anderson

I'm still trying to find out what makes people call the ball drive something other than a "true omnidirectional" fully holonomic system.

Since only the front wheels can impart a sideways force on the robot, the robot will turn (w/ CoR between the back wheels). If all 4 wheels were balls, it would be a true-omnidirectional drive. As it is now, the robot drives more like a car, where the front of the robot can go sideways, while the back of the robot doesn't.