If you make anything that moves, like a robot, you quickly realize that turning can be a pain. That’s why there are a number of designs for wheels that can go in different directions. One of the most common is the mechanum wheel. [Jeremy] explains how they work by filming them from below on a transparent table. You can see the enlightening video below.

If you haven’t done anything with omni wheels before, it is disconcerting to see wheels rotating one way causing the vehicle to move at a right angle to the rotation. But this is very useful when you build robots or — as he shows at the start of the video — a forklift.

Mechanum wheels are similar to omni wheels, but with some differences. In particular, omni wheels have rollers at a 90-degree angle so they drag in the “wrong” direction. The mecanum rollers are at 45-degree angle. That might seem like a small difference, but it means that all rotation translates and requires some vector math, as the video points out.

Many years ago, we were surprised to learn you could build strange wheels from wood. We like using omni wheels in a three-wheel configuration often called a Kiwi drive.