The Light Painting Idea and how hack make it happen
hack into the z axis motor control on tiny g to use it as a button to toggle flash light on and off so that jogging tool path won't mess up the drawing. Reading the high current signal is very tricky.
Doge vs Corbu
using the machine to draw a perfect portrait for Corbu the corgi.
the light painting
We want to create a constantly changing painting. Photoluminescent canvas become a perfect canvas for it, for you don't need an eraser for the machine to redraw the painting.
Ideally the machine should look like a frame hanging on the wall.
the z axis has to be able to turn on and off to skip drawing the jogging tool path
the solution is directly reading from the motor control of z axis. Once a pulse is detected by a seperate microcontroller, it will be treated as a toggle to turn the uv flashlight on.
the tricky part is to read the high current input from the motor controller. One is dealing with the high current, the other is the bouncing. Bouncing is avoided by adding smoothing and delay. Resistors is added to the microcontroller input pin to reduce the current.
Another tricky thing I found out that you have to make sure that z axis is only turned on when it supposed to move. The default option is to turn all axis on while any of them is moving. That option will effect the readings and add potiential risk that light will turned on or off when x or y axis star to move.
It works out pretty fine after a long dreadful tuning. The microcontroller report the default state reading, last and current reading and its state everytime it get toggled.
not very robust yet though
end effector mounted on the machine.
let's do a test first.
unity collaborated and axis polarity is reversed if needed.
after drawing Neil's eyebrow, the microcontroller missed one toggle so it start to draw on the jogging tool path instead of the what is supposed to draw. The system is fragile in two aspect. One is if it is mismapped one time, the whole latter work flow is ruined. And another thing is that using resistor to deal with high current is very unstable. It will start to release a lot of heat after a while and effect the overall readings.
three of us stay to fine tune the machine and draw the portrait for corbu. The resistor problem is still unresolved.
corbu is very happy. And we also draw a flower for him.