By using strings, pulleys, weights, ultrasonic distance sensing, a radio transmitter, geometry, and some advanced filtering algorithms, we have developed an efficient, non-intrusive and versatile method for encoding a blackboard at a high resolution; all for less than 40 dollars. See it here.
Step 1: What You Need
- pulley x2
- pvc pipe
- duct tape
- ultrasonic distance sensor x2
- microcontroller (arduino preferred)
- circular disk weights that fit in pvc pipe
- radio transmitter
- code found at https://github.com/harrisonzhao/string2string
Step 2: Building It
1. Add the pulleys to the top of the pvc pipe.
2. Cut the string and attach weights to ends of the string.
3. Run the string through the pulleys and into the pvc pipes.
4. Attach distance sensors to the bottom of the pvc pipes.
5. Secure chalkholder with chalk in the center of the string.
6. Connect the distance sensors to the arduino.
7. Wire up the radio transmitter to the arduino.
8. Wire the distance sensors to the arduino.
9. connect the arduino the the computer.
10. Follow the instructions for installing the software on the github page and reference video for calibration.