I quickly knocked together this Egg drawing robot after seeing the “EggBot” somewhere online. I’ve been experimenting with building a Lego motor/switch/servo Raspberry Pi controller and it seemed like something that might demonstrate some capabilities of the various parts needed.
There are three servos: Pen Lift, Rotate egg, Side-to-side for the pen.
The servos are controlled using ScratchGPIO and to make the range of the servo match my coordinates I needed to dust off my O-level maths for the straight-line formula: y = mx + c
Ultimately, the project was a minor success. I’ve learnt that the egg needs to have warmed to room temperature otherwise the condensation makes it too slippery to grip. I also needed a sharper pen – I seem to have picked a “bluntie”.