Mecanum wheels are a nifty invention that lets a vehicle drive sideways by attaching small rollers to the outside of the wheel, angled 45 degrees off the main axis of rotation. I’ve always wanted to play with them, but could never justify the cost of buying them pre-made. Each wheel alternates the angle of the rollers, so when they counter-rotate, the vehicle can drive sideways. Forward, backward, and diagonal translation are also possible, as well as skid-steering-style rotation.
Though fun and entertaining, they’re also confusing to contemplate and a little unnerving to watch in action!
Here’s a sample video of the rover driving around! (This particular rover is nicknamed the “MecaMuskox” because it usually has a musk ox and a bear driving around on it.)
Thankfully, a Robotics and 3D Printing class project gave me a perfect excuse to try to make some. The idea was to challenge myself to do the entire design 100% from scratch, including figuring out how to determine the shape of the rollers around the edge of the wheel, which seemed like a particularly complicated part of the design.
The original idea was to explore ways to generate mecanum wheel shapes that permitted tinkering with the driving parameters in order to create a variety of shapes. The first version of that is published on Thingiverse: Parametric Mecanum Wheel Generator Tool. It requires OpenSCAD, a free tool for creating 3D objects using programmatic syntax.
Assembly of the wheels is pretty simple. The bearings should fit snugly in the angled spokes from the hub, and the roller halves screw together with a screw serving as the roller axle and the lock nut held by the matching hole cut into the opposite roller half.
Just having wheels wasn’t much fun, so I put together a fairly simple robot using some motor controllers, a bluetooth serial modem, and a LPCXpresso 1769 board. The rover also needed a frame to hold some small gearmotors and a battery. It also includes a scaffold structure to hold the electronics and a cover that I tried printing in clear PET plastic, with mixed results.
Here’s all the objects on Thingiverse: All-3d-Printed Mecanum Wheel Rover using Parametric Wheels