WristBot Technology Proof-of-Concept

This is a gallant attempt at immortality by creating a drummer-bot with a wrist action, for use with a drum machine, to create more realistic sounds and feels than the drum machine's in-built samples. Essentially, using MIDI velocity data, mapped to Arduino PWM, applies a light voltage for soft hits and near full voltage for hard hits to pull an actuator to make the stick (or beater) hit the drum. On MIDI note-off or timeout, apply a light return/hold voltage to quickly restore the stick (or beater) to ready position for the next MIDI note. One control unit per drum or cymbal, up to 4 actuators per drum or cymbal, depending on that drum or cymbal's complexity.

For example, 2 sticks for snare, plus a mechanism to drop the right-stick height on MIDI "sidestick" note for rimshots requires 3 actuators. Hi-hat requires 2 stick actuators and 2 top cymbal actuators for half closed and fully closed. (PWM alone would not be effective enough.) Toms, percussion and straight cymbals would have a single actuator.

I'm using 2 digital outs on the Arduino to generate opposite hand logic at the inputs of the H-Bridge as my component count is already high for through hole construction on a small circuit board. I'm not set up for SMD in my home workshop. As the ide is to create an unobtrusive machine to clip to each drum, the circuit board needs keep the component count down. I'm trying to stay under a 90x60 millimetre footprint for the circuit board, LCD and buttons. Yeah, laugh now :-D

Each drum would have its own WristBot installed, each WristBot is daisy-chained via MIDI from drum machine to last in the chain and responds to its specific MIDI notes, setable via an LCD screen and a button pad.

This circuit and test code is shared under a Creative Commons 4.0 Share-Alike, With-Attribution, Non-Commercial licence. You may use this, and my blog which links to this, to build your own, or one for a friend, at cost, but you may not profit of this work in any way. Any software is under a BSD licence as Australia is still a bit iffy with CC4.0. No git repo for this yet. Will post that on my blog when I get to the "real coding" stage. This is just sim code to prove the H-Bridge and PWM.


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