Page 313 - Handbook of Biomechatronics

Upper and Lower Extremity Exoskeletons 305

duty is to control the position or force of the exoskeleton joints. This con-
troller interacts directly with the exoskeleton (Anam and Al-Jumaily, 2012).
In the usage-based control systems, the exoskeleton control system can
also be categorized according to the sort of applications such as the VR con-
troller, the tele-operation controller, and the gait controller (Anam and
Al-Jumaily, 2012). This controller has been applied in the most upper-limb
exoskeletons for use on VR controllers; for example: in performing therapy
exercises, it guides and helps the patient to carry on the tasks such as a virtual
object reaching, an object moving by virtual hand, a ball game, a labyrinth
game, a virtual wall painting, and a reaching and motion constrain task
(Anam and Al-Jumaily, 2012). In those applications, the exoskeletons are
considered as haptic devices.

4 EXOSKELETONS: CHALLENGES AND TRENDS

4.1 Applications
Trends of exoskeletons can be split up into two different applications: med-
ical and nonmedical. Medical applications focus on enhancing or recovering
human motor function for a wide range of patients several neuromotor dis-
abilities. On the other hand, nonmedical applications focus on the industrial,
military, and entertainment fields.

4.1.1 Medical Applications
Rehabilitation applications are one of most dynamic fields for exoskeletons,
which are designed to assist paralyzed patients, and they should be able to
respond to any command control made by the patient. This must be based
on a precise control of the mechanical interaction with the patient’s limb
(Ruiz et al., 2008). Furthermore, with other applications, more than
assisting the movement, the goal is to help the patient recover his/her sen-
sorimotor capability. Brain computer interface systems promise to enhance
application for sensorimotor and neuromotor rehabilitation of patients
integrating user commands directly from brain. Recently, a study of a
mind-control exoskeleton that permits to a patients group regain sensation
and move previously paralyzed muscles was done by Donati et al. (2016).
The biological actuators of human body muscles can be used instead of
external actuators. For this purpose, a controlled electrical stimulation of the
muscles leading to their contraction can be applied (Doucet et al., 2012).
The electrical stimulation can be used to generate muscle contraction in
otherwise paralyzed limbs to produce functions such as grasping, walking,