Robo-Drummer: Hi-Hat - Early Explorations

No, they really do! As a weird example, I've been "researching" Arduino-based, robotic drum machines - Heath-Robinson affairs that allow a drum machine to play a real drum kit, instead of stored sounds. How do bicycles make this better? Bowden tubes. "Bowden tube" is the engineering name for the outer sheath of a bicycle's mechanical brake cable. You might call it "the hose" or just the "outer."

The whole mechanical brake cable has not been used on one, single robotic drum system I've seen, yet, for the hi-hat, the upper and lower cymbals that a drummer operates with a pedal, as well as hitting with sticks, all have these complex linkages and gadgets and firmware code that gives the effect of half-pedal, rather than an actual half pedal. They're using car door lock actuators (solenoids) to do this, these things are on or off, they don't have a half position. Or do they?

Spoiler alert, they do, but the solution is mechanical. The fully closing solenoid gets attached to the pedal closer to the drummer's heal position, the half closed solenoid attaches closer to the toe position. This way the same amount of movement in each solenoid results in a smaller movement for the toe end of the pedal or, a larger amount of movement for the solenoid operating the heal end. As I want to only minimally modify my drum kit, I want it to stay human playable, the only way to do this is with bicycle brake cables, slipped into keyholes drilled into the pedal, and pulled by the solenoids monted on the cymbal stand riser, like this.

See? Bicycles make everything better!

So, by using 2 car-door lock solenoids and, a bicycle brake cable for each, one can mount the solenoids away from the hi-hat pedal, but have the closed signal fully close the cymbals for that "tick, tick, tick" sound, and the half-pedal signal half close the pedal for that "hiss, hiss, hiss" sound, or even work them alternately for a good, clean, offbeat "tissup, tissup, tissup..." from sould and disco. The solenoids mount on the cymbal stand riser, the cables pull the pedal from underneath and, if the closed cable pulls, the half cable is free of the pedal, so just sticks up, above the pedal, and vice-versa. Elegant. It's like my version of the Industry Super Fund ads in my country - compare the pair, same pull, longer travel. Just by pulling on a different position for each cymbal postion.

Author's note, republished from my cycling blog, where it was more intended as a brag about how cycling isn't only a solution to traffic congestion, it makes all aspects of life better. As an aside, the bicycle almost in a generation causes an end to in-breeding, too. Look it up.


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