Hi, i'm still developing my robotic arm but instead of wooden arm now made from alu. You can see it under this link:https://www.youtube.com/watch?v=nW0IslMvxqQ
. I use RPi as a main controller and it has some additional functions like HMI, sensor collector. RPi is connected via i2c interface with few Uno which are responsible for generating squared wave and collecting encoders impulses.