The price of a new prosthetic arm could range from a few thousand dollars to the tens of thousands, which puts the cost out of reach for most people. Ahmad Ikram recognized this need and decided to develop and create a much less expensive open-source version with myoelectric features.
In the beginning of this project Ikram opted to go with the 3D-printed design of the InMoov arm by French artist Gael Langevin because of it being easy to make. The hand is made up of one wire that is connected to each finger, and the other ends are wrapped around a motor Horn so that the finger will bend when the servo moves. A Myoware sensor for muscles is responsible for analyzing the electrical signals produced through muscle contractions and converts them into a usable analog voltage, which can be taken into account by an Arduino Nano’s analog port.
The program Ikram designed to run on the Arduino simply reads the continuously readings from the myoelectric sensor, and then checks to see whether it is above a specific threshold. When this is the case, the servos will be placed in a way that allows the finger to contract or release tension on the wire and causes finger muscles return the original position.
For more information about this project, check out Ikram’s Instructables article here and view the demonstration video below.