A ground-up redesign of the original Ball Drive by FTC team 4042. Features spherical wheels to allow for holonomic motion. Designed for use in the FIRST Tech Challenge.
Most components can be 3D printed on any FDM printer to reduce costs
Weighs in at under 8 lbs by minimizing use of metal components
Custom gearboxes off of standardized DC motors for maximum compactness
I started this project back in 2021, wanting to create a more practical, useful revised version of my robotics team's prototype ball drive (seen below) While it functioned as a concept, that drivetrain had many issues that I set out to resolve, including the following:
High cost of production: Most of the components were custom machined, requiring specialized machinery inaccessible to most FTC teams.
Weight: The original ball drive weighed about 20 lbs (including electronics), which is already half the FTC weight limit.
Speed: In addition to its weight, it was geared for high torque, rather than maximum power output, reducing speed
Mounting options: Not only did the prototype lack dedicated mounting options, it was poorly optimized in compactness, leaving little room for mechanisms like intakes and lifts.
The steps I took to mitigate these issues were the following:
The frame is constructed from standardized carbon fiber tubing and 3D printed components, reducing the total weight by a factor of 3. This also eliminates the need for specialized manufacturing capabilities by taking advantage of the strengths of FDM printing.
The drive system uses bare NeveRest motors, meaning teams can reuse motors with broken gearboxes, while also saving on space within the chassis itself. The gear ratios are set to maximize motor power under expected FTC loads, meaning better acceleration and top speed.
The driving colsons are reduced in diameter, meaning they take up less space, while also reducing the gear ratio needed in the motor gearbox - further reducing weight and space
The secondary drive wheels have also been moved to be horizontal with the sphere centers, reducing the overall height of the robot and eliminating the need for expensive omniwheels.