An Introduction to Biomechatronics - Biomechatronics in Medicine and Healthcare - page 4

assisted mode and continuous passive movement (CPM) mode, it was reported
that the motor improvements by the active-assisted robot treatments were better
than those with CPM by retraining and posttraining evaluations (Volpe et al.
(2000)).
Therefore, the robots providing active-assisted treatments will usually follow a
user's intention to complete a desired task. In robot-assisted physical training with
active-assisted movements, voluntary efforts from a patient are involved, which
could result in more significant motor improvements in stroke rehabilitation when
compared with a continuous passive movement.
1.2.3 What would be a Biomechatronic System Look Like?
Biomechatronics can be analyzed by analogy to biological systems integrating a
musculoskeletal apparatus with a nervous system (Bar-Cohen, (2006)). Biomecha-
tronic systems integrate mechanics, embedded control and human-machine inter-
action (HMI), sensor, actuators and energy supply in such a way that each of these
components, and the whole biomechatronic system, is interacted with the user
( Fig. 1.2 ). Van der Helm (1994) reported that a model structure of a robotic system
could be divided into four blocks:
(1) The linkage system is the mechanical structure of the robot like the human
bones, intermediate joints and ligaments.
(2) The actuator system by the electrical motor is used to generate forces and
power the same as the function of muscles.
(3) The sensory system adopts the transducer such as potentiometer and force
sensor to measure the position, velocity and force. It is similar to the function
of muscle spindles and Golgi tendon organ.
(4) The control system is applied to the motor controller such as PID control and
Fuzzy logic to control the movement of the robot like the function of central
nervous system.
Biofeedback involves translating the physiologic activity of a patient's muscu-
lar response into a visual or auditory signal which allows him/her to be aware
of the volitional changes in motor unit activity. The subject can facilitate or
inhibit the muscular activity depending on the guide. The mechanism by which
biofeedback can help to improve the outcome in the rehabilitation may be the
reasons that the subjects can gain conscious control over undamaged upper neuron
pathways which are in turn able to promote the restoration of missing functions.
In practice, biofeedback is often combined with traditional physiotherapy as a
useful complementary unit. EMG biofeedback has been applied on the recovery
of upper limb (Basmajian et al . (1982)) and lower limb (Bradley et al . (1998)). Stein,
(2004) expected that robotic and sophisticated biofeedback technologies for motor
relearning after stroke might converge into combined training systems (Stein,
(2004)).