omniwheel?

has them.

Mitch

I thought the omniwheel was clever but overrated; the ones I've tried didn't travel smoothly in any direction. You may be interested in something like a "ball transfer"; search for that term on google or

to see what I'm referring to; flange mounts are on pages 1118 and 1119. These are somewhat noisy due to the ball bearings that hold the main ball, but they slide quite smoothly in any direction.

Daniel

Most robotics researchers gave up on those things back in the 1990s. They work fine on hard, flat lab floors, but little else. They don't work well on carpet, or dirt, or irregular surfaces. There's a big set of those wheels on a robot in a glass case in the lobby of the Stanford computer science department, but that robot was, actually, a dud.

People used omnidirectional drivewheels before control for nonholonomic robots was figured out. Now that control systems can put something with a more reasonable drivetrain where you want it, the omnidrive wheels aren't used much.

A simpler omnidirectional drive train is the arrangement where you have three ordinary wheels, all of which are pointed in the same direction but can be pointed in any direction. This takes one drive motor and one steering motor, plus some belts.

John Nagle Animats

Interesting, but how is that holonomic? You can travel in any direction, but how do you turn to face any direction?

Usually, you have a turret on top, so the useful parts face in the direction of travel.

Several companies, including Cybermotion, used to make such machines, but that approach seems to be obsolete.

John Nagle

So does Kornylak:

Mike Ross

There has long been a debate whether a synchro drive is truly holonomic. I'm not sure that it is, in the strictest sense, but to the observer watching it move, it appears to exhibit the qualities of a holonomic system. The technical literature seems about evenly divided these days.

-- Gordon

Really? Their current products still appear to use synchro drive (six wheels instead of three, but the same general idea -- each of two wheels are mounted as pairs, I guess to facilitate traction).

-- Gordon