If you’ve dealt with robots or other wheeled projects, you’ve probably heard of mecanum wheels. These seemingly magic wheels have the ability to move in any direction. If you’ve ever seen one, it is pretty obvious how it works. They look more or less like ordinary wheels, but they also have rollers that rotate off-axis by 45 degrees from the normal movement axis. This causes the wheel’s driving force to move at a 45 degree angle. However, there are a lot of details that aren’t apparent from a quick glance. Why are the rollers tapered? How do you control a vehicle using these wheels? [Lesics] has a good explanation of how the wheels work in a recent video that you can see below.
With four wheels, you can have a pair of wheels — one at the front right and one at the back left — that have a net force vector of +45 degrees. Then the other pair of wheels can be built differently to have a net force vector of -45 degrees. The video shows how moving some or all wheels in different directions can move the vehicle in many different directions.
Continue reading “All About Mecanum”
Mechanum wheels are great, but you have to have them perfectly alined or they come across a little clunky, giving your robot a herky-jerky movement. Robotics educator and supreme LEGO builder [Yoshihito Isogawa] built a mechanum-wheeled rover that has the angles right: each wheel consists of 12 smaller rubber tires angled at 45 degrees. The key to the project is Part Number 85940, accurately if unsexily named “double Ø4.85 hole w/ Ø3.2 shaft”. It consists of a double technic hole with a shaft projecting in a 45-degree angle.
Unlike his omni-roller project with 3 large wheels and the mechanum tank treads he built for another project, this one features the gold standard of mechanum movement: creepy agility. He also did a version with 9 side rollers per wheel, and it was nearly as stable.
Hackaday loves [Yoshihito]’s great creations, which are as beautiful and elegant as they are functional. His all-LEGO centrifugal pump and his spirograph machine make expert use of parts to make the builds as simple as possible.
Continue reading “Freakishly Agile Crawler Rocks All-LEGO Mechanum Wheels”