Biomedical Engineering Reference
In-Depth Information
information. Similarly, tactile feedback can be used to restore sensation in the
impaired limb; typically small vibrator motors can be taped on the subject's hand
or arm to stimulate the skin when a task is successfully performed.
Motivating rehabilitation exercises may be implemented as goal-oriented ther-
apeutic games with a score indicative of the performance, and the possibility
to choose between different levels of difficulty adapted to the impairment level.
Indeed, therapeutic programs that build on a base of successively more demand-
ing performance levels and that promote a sense of personal responsibility for
accomplishment is believed to be more successful and motivating (Lewthwaite
(1990), Johnson (2006)). It is debatable how sophisticated and complex these
virtual reality environments need to be as stroke patients are typically older and do
not have previous experience with video games, may suffer from cognitive deficits,
and fatigue easily.
Exercises implemented on the HapticKnob and the HandCARE follow this
concept, progressively requiring more accuracy or more force for successful com-
pletion. Simple and intuitive visual feedback is used, consisting of selected pic-
tures that are visually scaled or rotated as a function of the motor task performed
on the robot.
Figure 4.4
i
llustrates the display presented to the subject during an
exercise with the HapticKnob, where the objective is to perform pronation and
supination movements with the forearm. The orientation and brightness of the
picture are modulated as a function of the rotation angle of the robot, such that
when the target is reached the picture is oriented normally. In addition to being
intuitive, this approach offers subjects the possibility of training with personally
selected pictures to further increase motivation and engagement in the therapy,
i.e. photo of the family members or of places the patient would like to travel to
(Lambercy
et al.
(2007b)).
Figure 4.4
Angular position of the HapticKnob during an exercise training prona-
tion/supination movements. Visual feedback is given by means of a picture whose ori-
entation and brightness are modulated as a function of the angular position of the wrist.
