Part of my PhD research at NYU-Poly involves predicting energy consumption in robotic systems, so I needed a robotic system to work with as a research platform to validate results. So I convinced my group mates in my Mechatronics class in the Fall of 2011 that we should build a robotic arm. I also wanted to use it as a project to learn motor control. I had some high torque servo motors
lying around from another project, but the control boards had been fried. Since a servo motor is just a DC motor, some gears, and an integrated potentiometer, I could still use those if just the control board was fried. So, I unscrewed the bottom cover, and used some desoldering braid to suck up the solder around the two motor terminals.
Then I was able to pull off the PCB. However, the 3 wires from the potentiometer were still attached, so I cut those and ended up with something that looked like this:
I had also seen this post on Instructables
by Chris Anderson on adding some potentiometers to a toy robotic arm to enable closed loop control. Since I decided to work with these hacked servos, my potentiometers were already integrated, so I was set. I want to share the process with you so you can start a little higher on the learning curve than I did.
By building a robotic arm, students will acquire assembly skills and be able to implement basic forward and inverse kinematics in simple Arduino code.