Cookie Bot is about half way complete. Mounting the stepper motors was non-trivial. The motors are temporarily mounted into the chassis. We didn’t know stepper motors could get hot enough to melt Legos! Heat sinks had to be added as a precautionary measure.

We built a box around the main drive motor that may be insanely over engineered…

We made a new chassis for Cookie Bot Proto 2. Click on the image to check out the video!

We weren’t satisfied with the DC motors – there’s too much gear chatter, not enough torque, and no precision control. So, we upgraded to stepper motors. We built the stepper driver circuit with a current feedback loop, but the H-bridges were overheating. We finally decided to go with an off the shelf solution and bought some stepper driver boards. We will need to make a new prototype to fit the stepper motors on the chassis.

We have completed several stages of the Cookie Bot Proto 1. In the first iteration, Corinna built a car to ride along a pair of rails built by Melisa. Donald built a mini car to ride across a the car on a middle rail. The second iteration revised Corinna’s car. Gears and actuators were added to the car, and the mini car was built into the prototype. Sophie and Corinna worked on adding a differential gear system to drive the car. This requires the right and left sides of the car to be symmetric.