Theremin-Style MIDI Controller Does It With Lasers

Strictly speaking, a Theremin uses a pair of antennae that act as capacitors in a specific R/C circuit. Looking at [aritrakdebnath2003]’s MIDI THEREMIN, we see it works differently, but it does play in the manner of the exotic radio instrument, so we suppose it can use the name.

The MIDI THEREMIN is purely a MIDI controller. It sends note data to a computer or synthesizer, and from there, you can get whatever sound at whatever volume you desire. The device’s brain is an Arduino Uno, and MIDI-out for the Arduino has been a solved problem for a long while now.

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Playing Rock, Paper Scissors With A Time Of Flight Sensor

You can do all kinds of wonderful things with cameras and image recognition. However, sometimes spatial data is useful, too. As [madmcu] demonstrates, you can use depth data from a time-of-flight sensor for gesture recognition, as seen in this rock-paper-scissors demo.

If you’re unfamiliar with time-of-flight sensors, they’re easy enough to understand. They measure distance by determining the time it takes photons to travel from one place to another. For example, by shooting out light from the sensor and measuring how long it takes to bounce back, the sensor can determine how far away an object is. Take an array of time-of-flight measurements, and you can get simple spatial data for further analysis.

The build uses an Arduino Uno R4 Minima, paired with a demo board for the VL53L5CX time-of-flight sensor. The software is developed using NanoEdge AI Studio. In a basic sense, the system uses a machine learning model to classify data captured by the time-of-flight sensor into gestures matching rock, paper, or scissors—or nothing, if no hand is present. If you don’t find [madmcu]’s tutorial enough, you can take a look at the original version from STMicroelectronics, too.

It takes some training, and it only works in the right lighting conditions, but this is a functional system that can determine real hand sign and play the game. We’ve seen similar techniques help more advanced robots cheat at this game before, too! What a time to be alive.