Page 229 - Control Theory in Biomedical Engineering

210 Control theory in biomedical engineering

direct transfer of mechanical power and information signals (Kazerooni,
1989). The difference between master-slave and extenders is that the human
operator is either at a remote location or close to the slave manipulator, but is
not in direct physical contact with the slave in the sense of transfer of power
as in the case of extenders.

Orthotic robots
The term orthotic is commonly used to define a wearable structure assem-
bled on the human anatomy for restoring a human function previously lost
(Perry et al., 2007; Polygerinos et al., 2014; Merchant et al., 2018; Radder
et al., 2018; Shen and Rosen, 2020; Armeo Power, 2020; among others).
Although orthotics restore the capabilities to natural levels, exoskeletons
can even increase them. For instance, The Man Amplifier (Clark et al.,
1962), conceived by Cornell Aeronautical Laboratory, Inc. (CAL), is one
of the first developed exoskeletons. It was created by employing powered
joints that are worn by a man to augment or amplify his muscular strength
and increases his endurance by performing tasks requiring large amounts of
physical exertion.

Prosthetic robots
A modern definition of prosthetics includes the terms robotics, control, sig-
nal processing, and human–machine interfaces. A prosthesis is a wearable
structure that replaces one missing part of the human body (often as a part
of the upper or lower limb). For many years, prostheses were considered as
solely mechanical parts; however, nowadays it is possible to connect directly
a prosthesis through the human nervous system to achieve more natural
movements.
In this chapter, we survey prosthetic robot technologies for upper-limb
devices. However, the technical aspects presented in this chapter are also appli-
cable to lower-limb prosthetic technologies (Voloshina and Collins, 2020).

3.2 Features

One of the most important requirements of any device interacting with
humans is safety. As exoskeleton devices move under close contact condi-
tions with the wearer, any malfunction can be seriously harmful to the user.
Mechanical designs should therefore consider the possibilities of unpredicted
erroneous operation of the device controller when it is actively actuated.
Limits to the range of motion can be set using a mechanical stopper or
corresponding structural designs so that the exoskeleton cannot force the