PROSTHETIC ACTUATION: A CASE FOR PNEUMATICS.

Electrically actuated hand prostheses have the disadvantage of a high prosthetic mass, a slow cycle time, vulnerability, and an excessive volume. Pneumatical actuation can overcome these disadvantages. To demonstrate the feasibility of pneumatic actuation a pneumatically powered hand prosthesis has been developed. A careful assessment of the system choice, the friction losses, the dead spaces, and the supply pressure level resulted in a low gas consumption, enabling the use of small disposable gas containers. The mass of the hand mechanism is 60 grams, the operating cycle takes less than one second, the hand size is comparable to the hand of a 2.5 – 4 year old child, and the prototype functioned well in the laboratory for over 75000 cycles. These results show that pneumatic actuation of hand prostheses excels electrical actuation.