By Robert Armiger and Carol Reiley

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We created Air Guitar Hero as a fun rehabilitation exercise for people with amputations. Here we’ll show you how to make an inexpensive version so anyone can play Guitar Hero without pushing buttons. It uses an electrode cuff, a modified Wii guitar controller, and open source code.

Wii-Hab Lab: How the Air Guitar Hero system works. When a muscle contracts or flexes, it produces electrical activity. While faint (in the millivolt range), these signals can be detected by placing electrode sensors on the skin. The technology to measure, evaluate, and process muscular electricity is called electromyography (EMG).

Air Guitar Hero uses EMG to send signals to the Wii console to control the game. But since the electrical signal generated by twiddling your fingers is very weak, additional computation must be performed to generate reliably accurate commands. The system uses pattern recognition algorithms to identify patterns in the EMG signals and decide which colored button to activate.

The algorithms require training data to provide examples of what signal characteristics to look for. First, you must correctly play on-screen notes with the guitar while the electrodes record your EMG signals.

Next, the recorded data is used to train a model for recognition the next time you make those movement patterns.

Third, practice makes perfect! Playing this type of video game can be useful for building muscle tone and dexterity.