Mecanum wheels: so cool…

… and that added wow factor when they start rolling sideways!

Mecanum wheel

This could be the perfect solution to simplify parking maneuvers. Just pull up next to that tight spot where no one else can fit, engage your Mecanum wheels and let the car slide sideways into the parking lane. The best part? All the wows you hear around you.

True, Mecanum wheels might not be the most fuel-efficient thing out there, but they sure bring a massive added value when working in cramped spaces where regular vehicles have a hard time navigating. A typical example is a factory environment, where narrow lanes and tight turns are the norm. That is where industrial AGVs (automatic guided vehicles) are mounted with special wheels that let them move in all directions: forwards/backwards and… sideways! They can even rotate on the spot, and follow all sorts of crazy paths you can think of.

After seeing one for the first time, the engineer in me immediately said: “I have to build one myself!”

LEGO AGV with Mecanum wheels

The first step involved learning about the mathematical model and the control strategy for those wheels. I quickly put together some simple code, packed it in a c library and tested on a computer-simulated model. I posted code and documentation on GitHub for those interested in the details.

It was then time to build the actual car. I decided to use LEGO for the body, since it provides a very flexible platform, and also because I have plenty of spare parts at home. I also picked stepper motors as actuators, a B&R PLC as the controller, and shopped online for four Mecanum wheels. Those things are cool, but they do not come cheap…

Stepper motors to direct drive the wheels

I made the chassis large enough to fit a battery and a Raspberry PI in the future, but for now I kept the costs down and left controller and power source outside the box. The main goal was to test the kinematic model and make sure that the calculations were correct. A future upgrade could see the little AGV turn into a self-driving car and maybe chase the cat around the house.

Here’s a video of all the cool movements the car can do. I already counted so many wows (including my own) when it starts driving sideways…

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