Digitally Encoding by Writing on a chalkboard - String2String

String2String is a new generation chalk-board that digitally encode writing on a chalk-board using strings.
Earlier, students and teachers use chalked-board which is not so expensive but it can't store the information written on the chalkboard. But now new era String2String chalk-board is very convenient to stores the information which are written on the String2String funboard.

The developers have used strings, pulleys, ultrasonic distance sensing, a radio transmitter, and some filtering algorithms to pull this off. Here is how String2String works:

The algorithm works by computing the difference between the position of each weight in the current and calibration position, effectively allowing us to accurately measure the distance of the chalk-holder from each pulley. This gives us an approximation of each of the three sides of the string, string, top of board triangle. From there, by applying the law of cosines, we can convert the position of the chalk-holder to x,y coordinates.

Using a wireless radio transmitter attached to a button, writing is only digitized when the button is pressed. A second button exists to erase the current state of the board.

The project is certainly intriguing and not too expensive to pull off. You can find out all about it on GitHub.

src: http://www.gadgetify.com/string2string/