RAT-A2E: Hair Controlled Robot

I got stuck on the idea years ago of a Ratatouille themed Virtual Reality game where you are a rat controlling a chef by pulling his hair. After learning for a while, I realized I just didn't enjoy game development as much as I did robotics. So in 2026, when I wanted to apply for Open Sauce as an exhibitor, I was brainstorming when I realized I could revisit this idea in a way that I had more fun with, so I applied for the convention with a mockup of my idea for a robot chef that could be controlled by pulling his hair. After getting accepted, I dove in and started building and testing and am really proud of how it all came together.

Challenges Faced:

• A lot of the 3D printed parts here could have been repurposed from existing models online, but I wanted to exercise some CAD skills I haven't had a chance to use so I modeled all of the parts from scratch. This includes all parts that went into the arms and controllers. This involved considering the weight of the parts and how the length of the arms would affect the amount of torque on the motors, as well as playing with the placement of the motors on the arms. On the second note, I initially placed a motor at each joint, but the weight of having a motor at the elbow caused some serious torque issues. This led to me moving the elbow motor to the shoulder and using a belt-drive system to move the elbow. This moved all motors to the pivot point and balanced as the elbow and shoulder motor were opposite each other, leading the rotational motor that raises and lowers the arms to have a small enough force acting on it to be able to effectively turn without slipping. 

• Designing a 3DoF control system for the hair came with a few failed attempts as I had never done anything like it before. Designing a control rig to use pulling hair to manipulate a robotic arm with full range of motion was complex, but working with so many moving parts was a lot of fun. I ended up using a joystick at the base for X and Y movement, and a linear potentiometer attached to an inner cylinder that can move freely while still affecting the joystick. This was a novel mechanical project for me as I haven't done much design work for moving electrical parts like this before and