Sprint 1 in Review

Hi all!
​
I’m Sawyer Vaughan, writing on behalf of our POE project team. I’m working with Mackenzie Frackleton, Scott Mackinlay, Frances Devanbu, and Kai Levy to create a polar printing press. The idea is a rotating assembly that actuates a pen or marker up and down. The assembly will be controlled by a Raspberry Pi, which will process an image and control the system to draw the image.

We’ve just completed our first sprint. This sprint’s goal was to create a functional sketch model of our mechanism. We began by discussing many potential ideas. Our ideas include rotating wheels with cars extending outwards, three rotating arms which have rotating arms attached, and one large rotating wheel with threaded rods.

We sketch modeled the first idea, in which three arms extend from the central hub with wheels on the end that roll. The arms rotate with the rotation of the central hub. The arms are threaded, so as they rotate, they drive the marker cars farther from the central hub. Thus, the extension of the marker cars is directly and linearly related to the amount that the central hub has rotated. We discovered a few problems with this design. First, it would be difficult to design a mechanism to keep the arms attached to the central hub but allow them to rotate. Second, because the distance that the cars travel is directly related to the threading, we can’t adjust it in software. This prevents us from adjusting the precision and speed of the printing press easily.

Then we sketch modeled one large rotating wheel. In this design, the marker is moved by an assembly that travels along a rail and threaded rod. The turning of the threaded rod is controlled by a separate motor than the central rotating motor. Thus, we can control the movement of the marker independently of the rotation of the wheel.

We’ve also begun working on the software on the other end. We’ve produced code using OpenCV and Python to decompose an image into gray and black shades. The Python code will save this in a representation that the Pi can understand.

Our code at this point in time can be found on GitHub here.

Until next time,
POE Polar Printing Press Project Team

---

Sketch Model

first iteration prototype with functioning dc motor

Sprint 1 Reflection