Overview

Over the course of four years, I served as lead CAD engineer for FTC team #8397. I was also a member of the mechanical engineering and programming teams.

In 2021, our team won the Vermont state championship and qualified for the world championship in 2019 and 2020.

Now, I serve as a mentor for the team and assist with CAD and mechanical design.

Drivetrain

Much of the CAD work I did over the summer of 2020 was focused on creating a customizable and reusable wheelbase that we could use from year to year.

When I joined the team, the drivetrain that was being used involved driving the wheels using motors mounted above the wheels. The motors were linked to the wheels using chain and sprockets.

This design was unreliable because the chains often slipped on the sprockets when they were driven at high power.

I also worked on improving our drivetrain that coupled the motors to the wheels using gears rather than the previous system which used chains.

This design had the advantage of eliminating slippage and disconnection issues. It also allowed us to move the motors from on top of the wheels, where they used space in the center of the robot, to the bottom of the robot, under all the other components.

However, since the motors were very close to the outside of the robot, they limited our options when it came to intaking devices that required ramps very close to the floor.

For the 2021 competition season, we decided to move to a larger size wheel than in previous years. We did this because there were elements on the playing field that we had to drive over quickly.

We also wanted to leave ourselves more room for an intake in the front.

To do this, we moved the motors for the rear wheels to be direct driven off of the motor shaft. Then we repositioned the front wheel motor above the wheel.

We decided to drive the front wheel and two other pliable wheels off of one motor so that we would have extra traction while surmounting the obstacles on the field.

We used chain and chain tensioners to couple the motor to the front wheel and the pliable wheels.

Over the season, our team was one of the most reliable at crossing the obstacles, which cut our times by a few seconds per cycle.

Tape Measure Arm

We used a stiff tape measure driven by three servo motors, which acted as an additional arm.

We used geared servos, which provided us with pitch and yaw control over the tape measure.

Two pliable wheels were used for the extension and retraction of the tape measure back into its housing. These wheels were machined to fit the contour of the tape measure precisely.

Baseplates

Our baseplates were designed for versatility and rapid prototyping during the season. We used a series of standardized holes to facilitate mounting directly to the baseplates.

These baseplates were fabricated out of 1/8” aluminum. I did the CAM and machining work for these pieces on the team's CNC machine.

Since we were concerned that the numerous holes in the baseplates would lead to decreased rigidity and possibly failure during periods of high stress, we preformed finite element analysis (FEA) with a sideload on the plate.

Our results showed that the added holes did not detract from the structural integrity of the baseplate enough to worry about its strength during competition.

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