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Applications and Implications

Goals

Final Project Proposal

I plan on making a low cost braille embosser. My machine will come with a simple GUI that will allow the user to translate any given text in Braille and emboss it on a continous feed roll of paper.

Who's done what beforehand?

Unsurprisingly I'm not the first one to attemp such an endeavour, the most prominent example being the Braigo Labs experience.
Googling around it is possible to find lots of previous tries on this same topic, even if on a smaller scale (they usually focus on the end effector).
These are some examples:

What materials and components will be required? Where will they come from? How much will it cost?

All the material are easily purchased locally or already in the fabinventory, bar the solenoid; making my own is for sure a viable idea, but I found that making an impromptu solenoid that can move a nail is one thing, but making a solenoid strong enough to serve my purpose is something else. Here follows a comprehensive bill of materials:

  • Solenoid - digikey - 13€
  • SMD components - fab inventory - less than 15€
  • 15mm OSB, 400mm x 900mm - any local wood workshop - less than 20€
  • Linear bearings x4, ball bearings x3, GT2 timing pulleys x2, belt < 2m - amazon - 20€
  • Tempered steel rods - just salvage them from your friends' machines (otherwise 20€)

What parts and systems will be made? What processes will be used?

I plan to use several processes to finish my project:

  • Computer-controlled machining:
    • The body of my machine will be made of 15mm thick OSB that I'll mill on the Shopbot
  • 3D printing:
    • Solenoid holder: the biggest discrete component, it will hold the solenoid in place and house the grinded nail that will do the actual embossing
    • Cable carrier: there will be a significant length of cable connecting the pcb to the solenoid block; to prevent this cable from interfering with the machine behaviour I plan to enclose it in a segmented cable carrier, similar to the ones used on the ShopBot
    • Misc: all the little connecting pieces (belt fasteners, linear bearings housing, rods supports) will be printed as required
  • Molding:
    • Paper feed rolls: in order to maximize the grip on the paper traction system I'll use 2 couples of ball bearings covered with a silicone ring
  • Electronics design:
    • ATMega328p based board: the machine will be driven by a custom made board based on the ATMega328p (in order to ensure max compatibility with Arduino libraries), housig 2 stepper drivers carriers, voltage regulation from 24V (external supply) to 5V, a MOSFET used as a switch for the solenoid
  • Interface programming:
    • Even if the actual translation work from normal text to Braille will be handled by Liblouis I plan to write a simple GUI in PyQT to make the process as easy and straightforward as possible
  • Embedded programming:
    • The GUI will send, via serial port, the unicode characters as bytes for the microcontroller to interpret, in order to move the end factor accordingly

What tasks need to be completed?

Future plans involve the implementation of extended 8-points Braille among the GUI options, designing a 6 solenoids version of the machine in order to greatly speed up the embossing times, rewriting the whole microcontroller code in pure C in order to definitely ditch the Arduino environment, switch from an ATmega micro to an Xmega microcontroller in order to take advantage of the USB connectivity, thus removing the serial cable (the end goal is to make the machine completely plug-and-play, as easy to use as possible for the end user).

What questions need to be answered?

With the project in its current form two main questions arises: how stable is the translation software and how reliable the paper feeding system is.
Concerning the first point Liblouis is a time tested braille translator, with an active community of developers; all the problems lie in my implementation of it, mainly on how it behaves with very long text (will it gobble all the available memory, bringing down the whole system? For the time being the longest text I tried to translate was the first 6 cantos of "The Divine Comedy").
The paper feeding system, while functional, can be vastly improved, decreasing the paper waste.

What is the schedule?

  • June, 21 - Project presentation
  • June, 28 - GUI completed
  • July, 12 - Machine rev. B assembled, "hello world" print
  • July, 20 (planned) - GUI rewriting (8 points braille)
  • July, 30 (planned) - end effector redesign (6 solenoids version)
  • Yet to be determined - switch from ATmega to Xmega, microcontrolle code rewriting

How will it be evaluated?

Ideally a full working system should be able to print any kind of text, of any length, without issues.
That being said, considering the aforementioned uncertainties that still lingers over my project I will consider myself satisfied with my machine printing a couple of lines of Braille text keeping the characters alignment and don't falling apart in the process. That would be a good starting point to start implementing all the features that would help my project evolve from a proof-of-concept, insiders-only fabbable machine to a real appliace that could find its place in small officies and households.