Persistent, dynamic information display

System design document

The project consists of two phases.

PHASE ONE:

• HARDWARE: Make a small prototype using an existing commercially-available plotter.
• oThis is working, however I will have to try other dry-erase boards to find one that erases better.
• SOFTWARE: Get scripted control of the plotter.
• oThis is working, however I will need to add additional functionality such as the ability to queue the commands sent to the plotter.

PHASE TWO:

• HARDWARE: Make a larger (few ft x few ft) prototype, this time building the 2-axis plotter from scratch, Arduino-controlled.
• SOFTWARE: Build a modular system that can accept any text or images as input, decides how to arrange the text or image on the screen, queues it until the plotter is ready, and plots it. This should accept any text or images from asynchronous sources such as text from webforms, html5 canvas drawings, harvested web data (such as twitter feeds via the twitter API), etc.

Preliminary components list:

Phase One is essentially complete, so I will list components for Phase Two.

• PLOTTER COMPONENTS: I have built a Reprap before, so will use some similar hardware since I’m familiar with it: For the scroller axis, NEMA 17 motors and a 608 bearing/shaft system. For the vertical (pen) axis, there are many varieties of homebrew plotters out there; here is one. I plan the vertical (pen) axis to be similar to one of those axes – belt-controlled, again with inexpensive 608 bearings and NEMA 17 motors. As a stretch goal I’d like a retractable dry-erase pen that doesn’t dry out, so may incorporate a retractable dry-erase marker with a linear actuator. Lastly, I have a good ol’ Arduino Megas lying around which can accept commands from the computer via USB, and I have a motor shield which can control the NEMA motors.
• SCROLL: As described in the Project page, for Phase Two I’ll have transparent plastic scroll, running on top of a plain-colored board. I’ve had more luck with really good dry-erase flexible materials among the transparent plastics rather than the white or other color dry-erase boards. Plus I can find it cheaper – flexible dry-erase board that is sold as such is expensive, while sheets of transparent plastic are cheap and many varieties exist.
• FRAME COMPONENTS: I plan a painted wooden frame made at Techshop where I have a membership. In particular, this time the frame will hide the mechanism so that from the front it just looks like a flat sheet. (Writer and eraser are not visible.)
• COMPUTER to issue commands. Right now I’m using my desktop but have a disused Chromebox that I can dedicate to this purpose.