Robot: Redesigning the Wheel

In my second year at McMaster University Mechanical Engineering myself and three others designed and built a robot for the ME2C04 Mechanical Engineering Design Project course. I was responsible for the mechanical design of the robot. The task was to build a robot that could complete a simple course in the fastest time possible, with additional design criteria of minimizing mass and cost, as well as maximizing buid quality. The main challenge was to design a robot that could perform this task without driven wheels (legs must cover an arc less than or equal to 90 degrees). The grading of the robot was relative to the rest of the class.

Design Goals

Maximize Effectiveness of Legs: After clarifying the rules with the professor, I designed a spring loaded mechanism to self assemble four legs into a wheel as the robot drives. This resulted in a the function of a wheel, while meeting the constraints.

Maximize Speed: To increase the speed of the robot I implemented a 3:1 gear reduction. I also implemented PTFE washers, graphene, and oil to reduce friction on the axle.

Minimize Weight: After researching the allowed batteries (AA) I discovered that lithium ion batteries were significantly lighter than alkaline batteries. Implementing these allowed my team to reduce weight relaative to other teams who did not discover this.

Results

Our team came first overall in the challenge, achieving the fastest time on the course, as well as maximum scores for build quality, and high scores for lightweightness, and cost.

Lessons Learned

I learned a lot about mechanical design over the course of this project.

I found it very valuable to plan out the electrical components early on, to maximize serviceability and ease of wiring.

Pushing out a prototype early on, allowed improvements to the design to be made, such as increasing the gear ratio.