So what do you do when you have a week of free time? Built a robotic arm of course! I had a few smaller servos laying around and a pan and tilt servo kit I bought years before for a camera. It was all the pieces I needed to make a 6 dof robot with a gripper. Luckily, I work at a company with a 3D printer, and there was a night of free time on the machine coming up. So I did some research and spent a few nights drawing the pieces for the arm in Google Sketchup.
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</div><div class="separator" style="clear: both; text-align: left;">Here’s a picture of the pieces being fabricated. It was a 9 hour print and used about 3 cubic inches of ABC plastic for the whole thing. I printed at the maximum resolution since there was a lot of spare time. Pretty amazing that we can just print objects these days. </div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: left;">
</div><div class="separator" style="clear: both; text-align: left;">The parts are printed with two materials, the main plastic and a support material. To get the parts after printing, we soak the whole thing, tray and all, in a bath to dissolve the support material, but it leaves the plastic parts untouched. After a night in the solvent bath, the parts were ready to be put together. </div><div class="separator" style="clear: both; text-align: left;">
</div><div class="" style="clear: both; text-align: left;">Another night of assembly, wiring, and testing, the robot was ready to run. The servos I have aren’t very strong so it needed a little help. One joint is counter balanced with 4 oz of lead weight to support the gripper, and the shoulder joint is supported by a few rubber bands. This allows the robot to extend fully without putting too much strain on the servos. Plus I can lift a little more weight, although its still very limited. Initial tests show it can support the weight of two pens fully extended. </div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><div style="clear: right; display: inline !important; margin-bottom: 1em; margin-left: 1em; text-align: right;"></div>
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<div class="" style="clear: both; text-align: left;">Now it comes down to the hard part, writing the control software for the robot. While the forward kinematics equations are easy and I can move the robots servos individually, I would like to specify better movements such as movement along lines or planes. I also want to control it by joystick, and possibly have control over the internet, but that will have to wait for another day. </div>