Mecanum drive question (Square configuraton?)

[Kevin Sevcik]

You DON'T want an O pattern when looking down at the top of your robot unless you want to lose the ability to spin in place. Only X pattern (top down) configurations will have turn in place ability, unless you significantly tighten your rollers.

The reason is fairly simple. Wheels can only exert force in a direction they don't slip in. If you think about a standard omni-wheel, you'll realize this. It can only push front to back, not side to side. Which makes it easy to turn and easy to push sideways.

Mecanum wheels have axles that are angled 45 deg from the direction of the wheel. This means they slip in one diagonal direction, and push in the direction of the axle that's touching the ground.

So you have a choice, all the axles pointing at the center of your robot, pushing into/out from the center of your robot (O-style), or all the axles pointing perpendicular to the center of your robot, pushing at right angles to your robot (X-style).

So, grab 4 students, put each on a corner of your robot and ask them to push on their corner to turn the robot in place. They're going to push their corner sideways, at right angles to the center, like the X-style. If you ask them to turn the robot by all of them pushing towards the center of the robot (O-style) they're probably going to give you funny looks and go find some screws to sort.

[Ram Raman]

where is the cheapes place to buy mecanum wheels from?

[James Tonthat]

Originally Posted by Ram Raman

where is the cheapes place to buy mecanum wheels from?

Here.