I was pleased to be selected to be a part of the Intel Edison IoT invitational here on Instructables (please consider voting if you like it!).The project that I proposed was an automated "light painter" which would use stepper motors to move an RGB LED around in space by winding the strings it was suspended from up and down.
The Edison made things interesting, since it allowed me to handle things at a higher level (I was able to do most of the project's code in Python) as well as providing useful features like WiFi.
The repeatability of an automated light painter allows for some interesting options, such as animation:
The RGB led is suspended from two strings, the other end of each is wrapped around a pulley on a stepper motor. By Shortening or Lengthening the strings, the LED can be positioned at any X,Y coordinate between the two motors.
The stepper motors themselves are each driven by a Grove I2C motor driver. The motor drivers receive commands from the Edison via the I2C protocol.
The colour of the RGB LED is controlled by an ESP8266 WiFi module, which receives commands from the Edison (or can be controlled manually by a laptop of cellphone). The LED and ESP8266 are powered by a battery, so they have the associated voltage regulation circuitry as well.
The software that handles the coordinate geometry as well as the stepper control, LED control and SVG importing is all written in the Python programming language and runs on the Edison itself.
Here you can see the "light pen" hanging in place, suspended from the two pulleys
And here is the result of moving it around while the camera takes a long exposure photo.
String plotters are by no means a new idea, but this one is the first I have seen with wireless control of an RGB LED over WiFi and driven by Python.
And this chap has done one with string like me, but only in one colour,
Why you should read
Learn how to
Even if you have no desire to build a string plotter, I hope that you will find something useful in here. I have tried to describe each module in a useful way, so that the concepts can be applied to other things too. One last thing. if you like my project, please consider voting for me in the contest, thanks!
Here is a list of all the parts that I used.
For the Mechanics
For the Controller
For the Wirelessly Controlled Light
For the Camera