This year, [Blecky’s] Hackaday Prize Entry is an air guitar which uses multiple LiDAR sensors to create the virtual strings. What’s also neat is that he’s using his own LiDAR sensor, the MappyDot Plus, an enhanced version of his 2017 Prize Entry, the MappyDot.
He uses a very clever arrangement of six sensors to get four virtual strings. Each sensor scans a 25-degree field of view. Three adjacent sensors are used to define a string, with the string being in the overlap of the outer two of those sensors. The middle sensor is used for the distance data.
For the chords, he started out using some commercially made joysticks but ran into some ergonomic issues. Also, the manufacturer was discontinuing the product, a no-no for an open source project. So he abandoned that approach and designed his own buttons. He came up with a PCB with a linear hall effect sensor and some springs on it. The button has a magnet attached to its underside and sits on the springs. That way he gets the press and can do vibrato as well.
He plans to use Bluetooth MIDI so that you can play the sound on a phone or laptop but for now he lights up an LED beside each sensor as you press the strings.