Omni-directional "Swerve" Drivetrain

As this was a season-independent robot, my role on this project was to do all the heavy lifting as I was paving a new path. However I also taught multiple others how to use a swerve drivetrain, and as of now still provide assistance if needed.

The robot was designed entirely in Onshape, an up and coming CAD platform that boasts great collaboration and awesome community made features. The CAD process took around 2 months to go from first concepts to final design, with many iterations that did not work out. In the end, our small team settled on the design shown in the below renderings.

Robot design CAD Document Here

To manufacture the robot, we had to use a combination of CNC machining and 3D printing. There were three main materials we chose, each with their own properties:

The first was PETG plastic. We chose this because it was strong and easy to 3D print. It was the obvious choice for things like pulleys, and the only option for the parts with the most complex geometries. In the end, the final robot required more than 40 hours of print time to make all the final parts, and around 80 hours including iterations and replacements.

The second was 6061 aluminum sheet metal. We needed something strong to hold the frame of the robot together, while also being light and machinable. The only aluminum plate on our robot took over two days to machine and countless hours to optimize for aesthetics, strength, and weight reduction.

The third, and final, raw material we used was 3mm thick carbon fiber (CF) sheet. We had originally planned to use 1/8 in aluminum, but the first plate proved too tedious to machine and required constant babysitting. CF on the other hand is very low maintenance when cutting, and can practically be left alone. The high cost of the material however led to use of CF only when absolutely necessary.

Some other raw materials were used as well, such as 1/8in polycarbonate, but this was purely for holding the electronics.

Once we had acquired all the parts to make the robot, it was time to put them together. Sadly, this was no easy task, taking 20 hours to get everything just right. Every part was designed with tight tolerances, so every mechanical connection had to be perfect. Once the sub-assemblies were dialed in, the whole thing was put together.