Picture of Robotic Arm with Servo Motors
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.
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marshallv14 days ago

Hey dustynrobots, I was curious of what material you used for the arms? It looks like thin aluminum pipe? I have to complete a similar project for school. Let me know. Thanks! :) Btw great video, I found the link below.

Cool instructable
I was working through this and got a bit confused with the definitions of the variables since I took kinematics a while ago. This is a diagram for the forward kinematics part attached.

Cool instructable, I was a disaster in my Control Systems class (20+years ago) so this is particularly interesting as a practical teaching tool.
AJMansfield2 years ago
This needs a video. I was so looking forward to the video that I thought would be on the last page, and I was sorely disappointed.
dustynrobots (author)  AJMansfield2 years ago
Here you go! I'll embed this in the 'ible too