3D Printed Robotic Arm

For my mechatronics project in my last quarter at UC Davis, all we had to do was control a DC motor using an Arduino. However, I was bored in the midst of the pandemic and wanted to go beyond this simple assignment and decided to make a robotic arm from scratch.

I knew nothing about robotics at this point, but did realize the motors would be too weak to lift anything on their own. Thus, I decided to use planetary gearboxes to amplify the torque output by the cheap Amazon DC motors. Since I had virtually no budget and only access to my 3D printer for this project, I designed 3D printed gears and lubricated them using my trumpet lubricants. Despite how horrific the idea of 3D printed gears might sound, this worked surprisingly well and yielded relatively smooth and quiet operation. Both joints utilized a 6:1 gear ratio. With filtering and implementation of the gearbox, the encoder was capable of reading 2465 PPR (pulses per revolution).

A basic proportional controller was implemented for this robotic arm. The value of the proportional constant K_p was kept at 0.12, where lowering it slowed the overall system response and raising it lead to erratic motor behavior.