Robotic wheels within wheels

The Rotacaster wheel.

Lego Mindstorms is a fabulous tool. It’s a great way to teach kids about programming and robotics, and people have done some amazingly sophisticated things with it. But it does have some serious limitations. Some of those limitations can be overcome by clever building, some by buying cool add-on parts from the US. Our biggest problem has been how to create a simple robot that can turn consistently and until recently I couldn’t find a good solution for that one anywhere.

So I was thrilled the other day to find a solution to the wheel problem; but, better yet, one created by a local company.

You see Mindstorms comes with three motors. So if you’re building a vehicle you generally attach a wheel to each of two motors and use them to power and steer the vehicle. The third point of contact with the ground is generally a little trundle wheel, much like the wheel on a supermarket trolley. And much like the wheels on a supermarket trolley the little trundle wheel generally works really, really badly.

So imagine how happy I was to stumble upon the Rotacaster omni-directional wheel. This is a really simple but clever device – a wheel that can roll sideways as well as forward. The main wheel moves forward; the little orange bits in the picture are independent wheels which allow the main wheel to also roll sideways.

Rotacaster, which is based just North of Sydney in Newcastle,  makes these for use in forklifts and other industrial arenas, but also makes them as add-ons for Lego Mindstorms. So I ordered a couple and tried them out the other day on a simple build and they work perfectly. Because the wheel is fixed it doesn’t require a complex turning mechanism to attach it to the robot, just an axle. And because it does not have to twist around to face in the direction the robot is moving, the results of a turn or forward motion seem pretty consistent – which in turn makes programming so much easier. And as a final bonus it looks cool.

So an absolutely brilliant solution from a local company. Enough to bring a smile to the face of any robot.

3 thoughts on “Robotic wheels within wheels

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  • February 12, 2013 at 11:16 pm

    Around 7 years ago I seen the Rotacaster Rollers on the ABC T.V.’s ‘New Inventors’. The beautiful design and manufacturing process really had my little-grey-cells up and running. I could immediately see a number of applications for the Rotacaster Omni-directional rollers, including as an add-on for my LEGO Mindstorms Kits.

    I’m very proud of convincing Mr Peter McKinnon of Rotacaster Australia that the 48mm rollers used in their multi-directional conveyor systems would make excellent omni-wheels for use on Holonomic ( and other types of Robotic Platforms.

    I also enjoyed the development journey I was taken on while experimenting with different compounds for the rollers and their suitability to the LEGO Mindstorms and Technics platforms. I was also very surprise at the amount of money Rotacaster committed to make it all happen, including hiring of specialized staff.


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