An affordable open-source robotic prosthetic arm 

For missing limbs, a robotic prosthesis represents a real and useful way to recover capacity. But such prostheses are traditionally very expensive and are inaccessible for a large percentage of people who would benefit from them. In an effort to improve the situation, Pavel Kochetkov by Weird Motions Lab designed this affordable open source robotic arm.

When it comes to a prosthesis like this, there are two great challenges. The first is the mechanical design, since it needs to reflect the user’s physiology, while it is powerful enough to be useful and comfortable enough to be practical. The second is control, because the prosthesis must be intuitive and perfect in daily use. Kochetkov exceeded both challenges with a budget.

This “bionic arm” strains the upper part of the arm with synthetic foam pads for comfort. The frame is a relatively light combination of 3D printed plastic and plastic. It is intended to replicate the functionality of the lower arm and hand. He does it with two joints: an elbow and a clamp. Those are acted by the servomotores of SERVO DS51150 DS51150 that operate under the power of an Arduino Leonardo Board.

The Arduino controls those engines according to the entrance of two sensors: a gyroscope and a myoelectric sensor. The gyroscope simply tells the Arduino the current orientation (in relation to the severity of the earth) of the upper arm. The myoelectric sensor is more interesting. Detects the muscle activity of biceps, so flexion is a control command. In theory, the user will develop muscle memory to control the arm and that will become without problems.

Kochetkov’s demonstration of the bionic arm is convincing. It is able to perform tasks that require a good amount of skill, which is impressive given the low cost of the prostheses.