Page 326 - Handbook of Electronic Assistive Technology

Chapter 11 • Robotics 315

• The type of applied actuators.
• The power transmission methods (gear drive, cable drive, linkage mechanism, etc.).
• The function/application (assistive, rehabilitation, performance augmentation).
• Their mechanical characteristics (end-effector or exoskeleton).

Upper Limb Robotic Rehabilitation Systems
In terms of their mechanical structures, upper limb robotic systems can be broadly clas-
sified into two types: end-effector-based systems and exoskeleton-based systems (Lo and
Xie, 2012).
Earlier systems that were developed were end-effector-based devices, which contact
the user’s limb at its most distal end. The joints of end-effector-based systems do not
match that of the human limb. These systems have simple mechanical structures and can
easily be adjusted to fit users with different limb lengths.
More recently, exoskeleton systems or devices mimicking the skeletal structure of the
limb have been developed, where the joints and links of the robot directly correspond with
human joints and limbs, and the robot axes align with the anatomical axis of the upper
limb (Gopura et al., 2016). Exoskeleton systems provide more independent and precise
control of the impaired limb.
Four main strategies have been employed when using robotic devices to support upper
limb rehabilitation (Huang and Krakauer, 2009). These are:

1� Passive: The movement is initiated and imposed by the robot.
2� Active assisted: The user initiates the movement but the robot assists the movement
along a predefined path.
3� Active resisted: The user initiates and moves against a resistance generated by the
robot.
4� Bimanual exercise: Active movement of the unaffected arm is mirrored by
simultaneous active/passive/assistive movement of the affected arm using the robotic
device.

Many of the robotic systems developed incorporate multiple operating strategies in a
single device.
Several reviews have been published exploring the effectiveness of robot-assisted ther-
apy for upper limb rehabilitation following stroke (Veerbeek et al., 2017; Norouzi-Gheidari
et al., 2012; Mehrholz et al., 2012). However, these studies have presented a mixed picture.
Norouzi-Gheidari et al. concluded that robotic therapy does not provide any benefit over
conventional therapy in terms of motor recovery, ADL, strength and motor control, but
additional sessions of robotic therapy in addition to conventional therapy promoted bet-
ter recovery of the hemiparetic elbow and shoulder (Norouzi-Gheidari et al., 2012). More
recently, a review conducted by Veerbeek et al. through meta analysis of 38 trials found
that robot assisted therapy in stroke rehabilitation for the upper limb led to small improve-
ments in motor control and muscle strength of the paretic arm and a negative effect on
muscle tone (Veerbeek et al., 2017). They did not find any effect of robot-assisted therapy