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Independent project · FIRST Tech Challenge

Custom Billet Swerve Drivetrain

Swerve drive was and still is very rare in FIRST Tech Challenge due to its complexity and lack of documentation. This project was the culmination of months of research, designing, manufacturing, and assembly.

Built
Summer 2024
Material
Billet aluminum & carbon fiber
CAD
Onshape

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Why swerve

A swerve drive includes an extra degree of motion compared to standard holonomic drivetrains. This extra rotation allows each module to steer independently, letting the robot move in any direction while holding its heading. In FIRST Tech Challenge, it is very uncommon because a mecanum wheel can do many of the same tasks without the extra complexity. However, because a mecanum wheel relies on rollers to generate force vectors in the lateral direction, it experiences more slippage and provides less traction than a fully optimized swerve drive.

The design

Each module includes a fully custom 5-axis CNC aluminum core pressed into an X-contact bearing to support smooth rotation. The gear ratio is highly tuned to minimize the coaxial effect (a force applied on the servo that is caused by the slight rotation of the wheel as it changes direction), as well as to move the robot at up to 6 feet per second.

What I shared

Working openly with another FTC team in Arizona and sharing the CAD process with the community, this project worked not only to conquer an extremely difficult challenge but also to spread an iterative and innovative design approach to even the most core and standard component of an FTC robot: the drivetrain.