Robot Drawing Arm

Robot Drawing Arm

Robot Drawing Arm

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I started playing with Arduino programming recently. My first project — a robot drawing arm.

The lines are a bit shaky. I think this has something to do with the Lego support arm rubbing against the table. My older son, Ben, suggested I try putting a piece of felt under it. Hopefully that will help. We tried an omnidirectional wheel from an Ikea filing cabinet, but it was too smooth, and the shoulder servo kept jittering back and forth. I think the weight of the arm caused it to overshoot its position so it was constantly trying to readjust.

I should also tweak some of the inverse kinematic math. The pen mount is about 1cm to the right and 2cm in front of the wrist servo axle. The current algorithm calculates the shoulder and elbow servo angles based on the wrist servo position. The offset makes the pen position somewhat unpredictable.

Here is Alex trying it out…

The next step is connecting the arm to this Processing sketch here. The program runs an edge detection filter, then finds pathways along the edges and computes servo angles to control the arm. It’s not especially fast, but it should work once I solve the alignment and jitter issues described above.



Thanks to Nick Stedman at the InterAcess Electronics Media Arts Center for the great Arduino workshop series.

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