Andrew Burks

HarmonicaBot

HarmonicaBot Begins

by on Oct.11, 2010, under HarmonicaBot, RobOrchestra, Robotics Club

The Carnegie Mellon Robotics Club has announced $500 in funding for HarmonicaBot!  This is good news, because there was no where else for funding to come from.  The one caveat is that I need to have a proof of concept in order to unlock the final $300 of funding.

During the presentation, some other interesting means of funding were mentioned.  It was recommended that I speak to Clippard directly to try and obtain my 12 solenoid valves for free or at a reduced price.  Also, an engineering professor at CMU who is very involved with harmonicas might be interested in doing something with this project.

Plug

In the hour before the funding presentation, I modeled and rendered a crude first iteration of the plug.  This version routes a 1×10 array of square holes on the harmonica to a 2×5 array of 1/8” NPT fittings on the back.  The harmonica sticks inside a bit, where two pieces of foam or rubber apply pressure to keep the harmonica up against the plug.

Harmonica in Plug

The next image is a cross-section of the plug.  The curved parts of the channel may seem to end before reaching the harmonica on the left, but they don’t.  Instead, one of them crosses out of plane towards you, and the other crosses out of plane into the screen.  This complex geometry is why the part needs to be 3D-printed or cast.

Plug Cross Section

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HarmonicaBot

by on Oct.08, 2010, under HarmonicaBot, RobOrchestra, Robotics Club

Autonomous Harmonica-Playing Robot

I have wanted to add a diatonic harmonica to the RobOrchestra since I joined the group in my freshmen year.  The Carnegie Mellon Robotics Club recently acquired a MakerBot 3D printer, so my dream has become a lot more feasible than before.

Harmonica - Hohner Special 20

Harmonica Interface and Control

The concept for the robot is simple: A 3D printed plug (with complex inner geometry) routes the 10 square holes of a diatonic harmonica to 10 NPT fittings.  The NPT fittings connect to 10 different solenoid valves, each corresponding to one hole on the harmonica.  This allows for individual control of the air going through each hole.

Achieving both “Blow” and “Draw” Notes

The solenoid valves all connect to a single manifold, which is connected to two other solenoid valves.  One of the two valves is connected to positive pressure, and the other is connected to negative pressure (vacuum).  Activating one of the two solenoid valves at a time can simulate a blowing or drawing, while the other 10 valves select any number of holes on the harmonica to play.  Unfortunately, like humans, this robot will not be able to blow in some holes while drawing from others.

Manifold - Iso

Harmonicas of Different Keys

The best part about having one generic plug to route the 10 holes to 10 NPT fittings is the modularity it provides.  Diatonic harmonicas come in all sorts of keys, but they all have the same shape.  Because of this property, harmonicas of different keys can be easily switched in and out of the mechanism.

Funding

The estimated cost of this robot is at $500.  This project is applying for RoboClub project funding, but will not be applying for a SURG.  The largest cost is the 12 solenoid valves at $20 each.  More updates and design will follow if the project gets funding from somewhere.

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