A mentor was describing a drive module that uses a ball instead of a wheel that is controlled and rotated to move the robot around. The module would be similar to a Holonomic / Swerve module. Both the mentor and I are unable to find the thread/ post where this idea was discussed. If someone recognizes this idea please link the post/thread where I can find out more.
Thanks in Advance.
I’m guessing it’s something very different from TechnoKat Ball Drive but similar in concept.
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.
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.
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.
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.
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.
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?
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.
What kickball are you referring to? The TechnoKats Ball Drive robot does use hollow steel balls, coated with a thin layer of polyurethane rubber to provide traction. You definitely don’t want to kick one.
Bed Bath & Beyond | The Best Deals Online: Furniture, Bedding, Rugs, Kitchen Essentials & Moree is similar to what was used.
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.
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.
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.
I’ve also done it numerous times with omni wheel based drives[1]. With a gyro it’s fairly simple actually. Ether has posted enough of the math at this point that it’s not bad at all. If you prefer to derive it yourself it’s some basic trig.
[1] https://www.youtube.com/watch?v=TW6fR-bQFgI In this video the driver is simply commanding the direction to go (field centric) and a rotation rate. The robot figures out everything else. No coordination needed, this was, I think, Brando trying it out for the first time.
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.