Robot Slide Whistle Orchestrion

I apologize for my crimes against all things Musical [Music] [Music] [Applause] [Music] d [Music] this was my installation at EMF 2022 I'd already built one robot slide whistle ages ago so I figured it would be easy to build three more and put them in a box and maybe it would have been if everything had gone to plan I started building this barely 2 weeks before the event and it's a miracle I got anything working at all it had been years since I built the first one and in that time almost every component had been a victim of shrink flation I bought four of what I thought was the same fan motor only to find that they were like miniature versions 40 W instead of 55 wat I bought several from different suppliers and none of them were any good all of them were smaller and noisier very irritating even the slide whistles had been shrunk I imagine that on a production run of a billion slide whistles shaving off a tiny bit of plastic saves a huge amount of money but for me the slide whistles being a slightly different size means I can't reuse the design files and everything takes longer mercifully I was able to get hold of the servo Motors although there is a newer version available there was still old stock of the ax12 a I could have solved my air pump problems by building Bellows and given enough time I would have but remember that each whistle needs a separately regulated flow of air the pitch depends on the flow rate so that would mean either four sets of bellows or some kind of regulating apparatus I didn't feel comfortable experimenting with in the time [Music] remaining [Music] [Music] [Music] oh the plywood enclosure is custom built though I didn't get a chance to finish the exterior in the back here we've got the fan motors the control board and power supply the gray fur is my attempt at soundproofing which is surprisingly effective this bicycle inner tube and elastic does a very good job of decoupling fan noise from the wooden box the circuit board is stm32 f401 black pill surrounded by some increasingly desperate transistor Arrangements see the way I wired up the very first slide whistle generated quite a lot of heat so I figured this time I'd do it properly and use mosfets but I made a small mistake with the level shifting that means that when the processor is in reset the motors all go to full power I added a hard cutout switch to the motor power but if you forget to hit that switch before reprogramming the chip you're faced with unbelievably loud screams as all the whistles jump up S octaves like ah ah we're programming ah after the third time this happened I added a whole load more transistors to reverse the logic level and stop it for good the googly eyes were a later [Music] Edition [Music] [Music] oh [Music] [Music] [Music] d [Music] oh [Music] [Music] oh [Music] [Music] d [Music] the original slide whistle did not need feedback you'd do a single calibration and it would then be reasonably in tune these slide whistles are not in tune even if I do a full calibration on each whistle individually it's not even close to being in tune the problem that I eventually discovered is that these fan motors are unpredictable I think it's the grease warms up if they've been on for a while and merely setting the power level is not enough to get a consistent flow rate I managed to partly alleviate this problem by drilling holes in the pumps to create an intentional leak which means we can run the motors a bit closer to full power the theory being if we can run them at a higher power level then the effects of friction will be less significant although this helped a little bit the results are far from adequate it's not like I haven't considered adding feedback I played a bit with adding contact mics onto each whistle but I concluded that it it would be very hard to isolate the pitch of just one whistle when all four are playing in instead what I'd like to do next is fit encoders to each of the fan motors and control them with a PID Loop if we can get predictable air flow I think most of our problems will go away at the event nobody seemed to care that it was Out Of Tune if anything that just made it funnier people really enjoyed the realtime playability I added a polyphonic algorithm that chooses the nearest whistle as you play each note that at least is one bit of the project that worked really well [Music] d [Music] I saw the comment requesting Beethoven's 9th Symphony on slide whistles and I concur that it would be Magnificent the problem is arranging music for robot slide whistles isn't easy the range is just one and a half octaves and the portamento is mandatory but we can partially solve our problems using software a few years ago I made a robot slide whistle emulator and using this we can get a very basic idea of what MIDI files will sound like when sent to the machine it runs in a web browser of course using web midi and if you'd like to have a go with it you can head to this address I don't expect anyone to do all of Beethoven's 9th but if you do come up with something nice then feel free to send it to me and maybe I can record it playing on the real thing as always there's more information on MIT cell.com and if you enjoy this nonsense and you want to send me money consider joining the [Music] patreon [Music] [Music] d [Music] [Music] oh [Music] oh [Music] [Music] d [Music] [Music] oh I

Channel: mitxela

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Id: 6JeV53LZ8ag

Length: 14min 20sec (860 seconds)

Published: Mon Apr 01 2024