This is a video of a low-cost prosthetic hand I made for my final year project at the University of Plymouth. It is controlled by myoelectric sensors attached to the users wrist. These are then amplified and filtered by analog electronics, before being sent to a microcontroller for analysis. The microcontroller I used was the Arduino Mega, this then sends signals to motor controllers, which control the individually powered digits. The hand also has force feedback, which is done by measuring the current across the motors which is high when they are being stopped by an object. The motors stop when an object is gripped and will increase the strength of the grip if more signals are received, when the grip is increased feedback is given to the user by way of a vibration motor. The resolution of movements is currently limited to just open and close, I did write software to recognise several grip patterns, but it was too unreliable to use permanently. This project was made for about £260 and all designed by myself from scratch.
Mechanically, brushed DC motors are used to actuate the fingers, with a servo controlling the opposable movement of the thumb, giving the hand 6 degrees of freedom. The motors connect to the fingers via steel tendons. The exoskeletal structure is made from aluminium which was designed in Solidworks and water-jet cut in 2D, the parts were then folded into the correct shapes by hand. The black coating is simply a cut up household rubber glove. It is powered by two 14.8V 1000mAh batteries, which give it a battery life of up to 12 hours.
It is my hope that systems like this could be developed at similar costs, meaning amputees will be able to afford advanced robotic prosthetics which are currently out of the price range for the average person.
http://www.openhandproject.org/
