Ethel the Penguin

Mechanical design

Snowball

I designed a simple 2 axis gimbal as an ergonomic and playful controller. Wire placement was taken into consideration, with appropriate yet subtle slots modeled into the form. 

Ethel 

Position actuation was achieved by implementing two, 2:1 gear transmissions to gracefully and realistically rotate the head and body. Each transmission couples the corresponding potentiometer and motor to mirror the snowball potentiometer positions. A challenge in the mechanical design was ensuring the proper alignment of the gears in the penguin’s head. To achieve this, I designed a 3D printed mount that constrained the potentiometer and gear while allowing enough clearance for the head to rotate. 

Modeling & Fabrication

I surface modeled the controller and penguin shells in rhinoceros for 3D printing on a Fortus 450mc and Makerbot. They were then post-processed with a coat of XTC-3D to smooth the surface before spray painting. Although this was my first major spray paint endeavor, I wanted to achieve a high level of accuracy in the appearance of the penguin. To manage the gradient on the head and body, I layered subsequently heavier coats of spray paint over the course of 6 hours. The white portions of the penguin were kept clean with precisely-cut painter’s tape. Ethel’s red hand-knit (from makeshift needles) scarf appeared during times when debugging got to be too much.

prototyping

To gain understanding of hardware components I iterated on several prototypes. The mechanical, electrical, and industrial design were iterated upon simultaneously to inform one another. As I was refining the model, I first set up the motors and H bridge circuit, ramping them up and down. The 1 DOF mechanical and electrical subsystems could then be integrated, and after refining the gear fabrication method, system timer, and proportion values, I tested the system with the form. This process was repeated to achieve the final 2 DOF design.