Page 184 - Handbook of Biomechatronics

182 Georgios A. Bertos and Evangelos G. Papadopoulos

1.4 Types
1.4.1 Mechanical—Body Powered
The key characteristic of body-powered prostheses is that the amputee senses
muscular effort to operate the prosthesis. The development of body-powered
prostheses was influenced by development of the aircraft flight technology in
the early 19th century and especially of use of the Bowden cable. A Bowden
cable consists of an inner core cable that is free to move within a sleeve cable
that is fixed in place at either end. Bowden cables are used to mechanically
connect the control sticks of the airplane with the airplane’s flight surfaces.
In that way the pilot feels connected with the control surfaces of the plane,
and thus has better control. Bowden cables have also been used in bicycle
brakes. Body-powered prostheses have not changed much after their intro-
duction in 1950s. Most of the time they were worn with a harness around
the shoulders where one or more Bowden cables are attached. The traditional
below-elbow, body-powered prosthesis has a single Bowden cable which runs
from the harness to the terminal device (Fig. 1). Opening of the terminal
device is achieved by glenohumeral flexion.

Fig. 1 Schematic diagram of a traditional below-elbow body-powered prosthesis with
harness. (From Northwestern University Prosthetics Research Laboratory (NUPRL).)