DotMatic: The Braille Printing Robot

DotMatic is a compact and user-friendly braille printer designed to improve access to braille to teach children. With its affordable, portable design, DotMatic provides a practical solution for creating braille documents and enhancing accessibility in everyday life.

dotmatic.clips.mov

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Project Overview

DotMatic translates text into braille alphabet patterns and prints them onto paper using a precise, motor-driven system. The design prioritizes simplicity, portability, and cost-effectiveness, making it ideal for classrooms and homes.

videobraille.mp4

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Materials Used

Hardware

• LEGO EV3 Brick: The core computing unit.
• LEGO Servo Motors (x3): Provides controlled movement for precise braille printing.
• Touch Sensor: Used for user interaction and operational control.
• Laser-Cut Wooden Gear Racks (x2): Custom-made for smooth and accurate linear motion.
• Foam Paper: Acts as the base below paper.

Software

• Programming Language: RobotC was used to develop the control logic and manage motor/sensor interactions.

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Key Features

• Child-Friendly Design: Portable, small, and intuitive, tailored for kindergarten-aged students.
• Affordable: Built with widely available LEGO components.
• Modular Construction: Easy to assemble and modify, encouraging experimentation and learning.

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How It Works

Understanding Braille Printing

Braille is composed of characters with up to 3 rows and 2 columns of raised dots per letter. DotMatic translates text into this tactile system and prints it on paper using precise motor control and a custom-designed mechanism.

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Before Printing

1. Text File Formatting:

   • Separate each word with a /.
   • End each sentence with a !.

   Example: hello/world!

2. Setting Up:

   • Place paper into the printer and secure it under the frame.

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Printing Process

1. Starting the Program:

   • The LEGO EV3 brick displays the message asking the user to press the Enter button to start
   • Once the user presses the "Enter" button, the program begins reading the formatted text file.

2. Printing the First Braille Row:

   • For each word in the sentence:
     • The crank moves down to punch the first dot.
     • The crank moves back up.
     • The cart shifts horizontally by 2.5 mm (the distance between Braille dots).
     • This process repeats for all dots in the first row.
   • When a / (word separator) is encountered, the cart creates a space by moving the distance of one letter.
   • After completing a word, the cart moves back to its starting position.

3. Transition to the Next Row:

   • The paper rolls forward 2.5 mm to position for the second row.
   • The second row of the sentence is printed using the same process as above.
   • After completing the second row, the cart resets, and the third row is printed.

4. Efficiency Consideration:

   • The robot prints each braille row for the entire sentence before moving to the next row. This minimizes unnecessary movement and improves stability.

5. Completion:

   • Once printing is finished, the LEGO EV3 brick displays "System Complete."
   • The user must press the "Down" button to stop the system.
   • The paper can then be removed and flipped to read the printed braille.
   • 

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Emergency Stop

• The touch sensor constantly monitors for an emergency stop signal.
• If pressed:
  • All motors immediately stop.
  • The EV3 brick displays an "Emergency Stop" message.
  • After 5 seconds, the program rolls the paper out for easy removal.

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Challenges & Solutions​

1. ​Cart Movement​:

   • 
   • Initial design took up too much space
   • Optimize the use of one motor and conserve space with a gear assembly on the side of the cart
   • As the motor rotated, the gears turned, moving along the wooden rack
   • Allowed for precise movement along the rack, using motor encoder counts for each degree of rotation

2. ​Vibrations When Punching​:

   • 
   • With every punch, the cart used to rise off the wooden rack
   • Negatively impacted printing by making spacing/punching inconsistent and less accurate
   • I secured the cart onto the rack at the bottom with LEGO pieces
   • Prevented it from going off the rack while still allowing it to move appropriately
   • Created a margin for printing braille since the bottom connectors hitting the frame prevented it from going all the way right ​

3. ​Crank​:

• https://github.com/user-attachments/assets/90ecc609-a5c9-40f2-b07d-f480e8e6cf2c
• Crank was not punching perpendicular to the foam paper, making printing less accurate
• I realized the stylus height kept adjusting and it vibrated with every punch because it dragged onto the paper
• I modified the crank and secured the stylus inside a U-shaped connector
• Through trial and error, I found the optimal stylus height and secured it

4. ​Stylus Tip​:
   • 
   • The tip needed to be fine enough to create raised dots in the paper without piercing through
   • Decided on using a push pin as the tip through trial and error

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DotMatic demonstrates the potential of using robotics to make education more accessible and inclusive, paving the way for innovative solutions in assistive technology.