Page 231 - Control Theory in Biomedical Engineering

212 Control theory in biomedical engineering

today’s body-powered prostheses are essentially adaptations of the Bowden
design (Zuo and Olson, 2014). Durable, portable, and relatively affordable,
body-poweredprostheses allow the user an impressive range of motion,
speed, and force in operating a terminal device by changing the tension
in a cable via preserved shoulder and body movements. Although prolonged
wearing can be uncomfortable, dexterous motor tasks are limited, and
appearance is not human-like, body-powered prostheses are widely used
(Ostlie et al., 2012).
With the design and development of mechanisms and technologies,
more sophisticated and active upper-limb prostheses appeared in which
moving parts were key elements. In this sense, body-powered prostheses
received an upgrade and thus gave more capabilities to amputees. For auto-
mation and better control of tasks, electrical-powered prostheses were pro-
posed. This technology adds electrical power sources to utilize electric
motors with batteries and some variations with different mechanisms
(e.g., gears and pulleys). In the late 1950s, the use of external power was
introduced in the United States to help high-level bilateral arm amputees
who were victims of war or accidents (Muilenburg and LeBlanc, 1989).
Another kind of active mechanism is related to fluid systems (pneumatic
and hydraulic), where the working principle is based on pressurized fluids
to move upper-limb prosthetic elements (Marquardt, 1965). The first myo-
electric prosthesis with clinical trials was reported by Alexander Kobrinski in
1960. It used transistors (Scott, 1992) such that identification, acquisition,
and interpretation of myoelectric signals of the patient could be better
controlled.
Another interesting concept is the use of “underactuated mechanisms.”
These systems have an input vector of a smaller dimension than that of the
output vector (Birglen et al., 2008). In this sense, underactuated mechanisms
for prosthetic devices are used to increase energy efficiency and optimize its
kinematics mimicking biomechanics (Massa et al., 2002; Cipriani et al., 2006).
At present, the main drawback of using a prosthesis is user rejection. Sur-
veys on use and satisfaction in using prosthetic hands showed that 30% to 50%
of upper-limb amputees do not use their prosthesis for activities of daily living
(Atkins et al., 1996; Schulz et al., 2001). Rejection is mainly caused by non-
intuitive control, lack of sufficient feedback, and insufficient functionality.

4.2 Body-powered prosthesis
Body-powered prostheses were the initial design of prostheses. The first his-
torical reference for these devices came in 500BCE when Hegesistratus,