Page 335 - Handbook of Electronic Assistive Technology

324 HANDBOOK OF ELECTRONIC ASSISTIVE TECHNOLOGY

ReWalk requires the wearer to use crutches to maintain balance. Some contraindica-
tions to using the ReWalk include:
• History of severe neurological injuries other than SCI (multiple sclerosis, cerebral
palsy, motor neuron disease, traumatic brain injury, etc.).
• Severe concurrent medical diseases: infections, circulatory, heart or lung, pressure
sores.
• Severe spasticity.
• Significant contractures.
• Psychiatric or cognitive situations that may interfere with proper operation of the
device.

8
7
REX (REX BIONICS, NEW ZEALAND) REX (Fig. 11-7) is an exoskeleton with actuators
at the knee, hip and ankle joints. It enables the user to walk and climb stairs. The
device is suitable for manual wheelchair users who can self-transfer and operate hand
controls. It is suitable for use with patients who have SCIs at levels up to C4/C5 and is
also being explored in clinical trials for users with stroke and multiple sclerosis. REX
is self-balancing and does not require any additional supportive aids or crutches
for balance. The legs of the device cover the user’s leg significantly more than other
devices, thereby increasing the bulk of the device. The system is operated using joystick
control with a user-friendly interface. There are two versions of REX – REX P (i.e., for
personal use and customised to the individual’s size) and an alternative REX, which is
designed for use in rehabilitation clinics and is adjustable to fit different users. REX
is CE marked in Europe as a Class 1 medical device under the European Medical
Device Directive.
9
HYBRID ASSISTIVE LIMB The Hybrid Assistive Limb (HAL) is a bilateral lower
limb exoskeleton that has been developed for both performance augmentation and
rehabilitation purposes. HAL has 3 DOFs for actuating the hip, knee and ankle joints. It is
a hybrid system, which allows a voluntary and autonomous mode of operation to support
gait training, depending on the treatment purpose and user’s capabilities. Its ‘cybernic
voluntary strategy’ is based on estimating the voluntary muscle activity from surface
electromyography signals and adjusting joint torques depending on the measured muscle
activity (Tsukahara et al., 2010). The second strategy, ‘cybernic autonomous control’,
is based on the user’s weight shifting and input from in-shoe force pressure sensors or
ground contact forces with the exoskeleton (Bortole et al., 2015). This mode is used in the
case of complete loss of voluntary activation of gait muscles.
The device is used with a cane for stability during walking. HAL for medical use is CE
marked as a medical device.

7 https://www.rexbionics.com/.
8 https://www.rexbionics.com/rex-for-home-use/.
9 Cyberdyne Inc., Tsukuba, Japan: http://cyberdyne.jp/english/.