Mass-Efficient Robot
Robot that delivers a 10kg payload up a 15 degree incline. Designed and manufactured all critical parts including a mass-efficient chassis, supports, gears, and wheels.
Key Features
Optimizing power to weight ratio with a mass-efficient chassis
Powered by 2HP Tamiya Gearbox
Sandpaper surface to increase friction on wheels
Taped the wheels to increase the friction on drive axle
Summary
The team and I designed a robot to climb a slope and deliver a significant payload of 10kg. Focusing on mass-efficient design, I used mechanics formulas and finite element analysis (FEA) tools on CAD to optimize the performance of our parts.
Time Frame
10 weeks (March 2023)
Team
Courtney Anderson, Anna Griffith, Ryan Oosting
My Role
Component Design; Finite Element Analysis (FEA); Testing
Methodologies
3D-printing; Resin Printing; Laser Cutting; CAD; Python
Brainstorming
We needed to have our robot do 100J of work, so our 3-person group converged on having it climb an incline. Using the coefficient of static friction, we were able to determine a relationship with the ramp angle. Also considering friction, we opted to drive the rear axle as it would have the most friction when climbing.
Calculations
To do 100J of work on a 15 degree slope, we needed a significant payload of 10kg/22lbs. We conducted back-of-the-envelope and FEA analyses to identify points of high stress, informing our design.
Prototyping
The initial prototype with built with laser-cut particle board. We soon discovered our top piece was structurally unnecessary, so we removed it to cut weight. A Python script helped determine the optimal relationship between gear ratio and wheel radii.
Iterating
As we began testing with greater payloads, the forces around the motor and on the gears increased and caused some components to fail. Namely, the motor housing was rotating and the gears were deflecting. Using force analyses, I was able to balance the motor housing and my teammate worked on the gears. Sandpaper was added to our incline to maximize friction.
Updated Chassis
The updated chassis was a one-piece, mass-efficient chassis printed out of resin. The updated gears had larger, deeper teeth and complete infill, increasing their strength.
Successful Run at 10kg on a 15 degree incline
Final Product
Ultimately, the robot climbed 0.6m up a 15 degree slope carrying a payload of 10kg/22lbs. New challenges arose at each turn as payload increased. It was a rigorous yet rewarding experience and definitely one of my favorite projects I did at Stanford.