Biomedical Engineering Reference
In-Depth Information
Figure 2.6
Endpoint trajectories of voluntary reaching movements to target R2. The figure
shows the endpoint trajectories early (red trace) and late (blue trace) in therapy. For color
reference, see page 211.
to their level of difficulty. Subsequently, this order of targets is used as the order
in which the subjects will practice robot-assisted movements in the co-operative
mode.
2.7.1 Preliminary Results
At the moment, three of the six stroke subjects in the experimental group have
completed the study. This section presents some of the preliminary results from
the analysis of the data collected during therapy from one of the subjects. The
results presented here are only preliminary results, as we are yet to perform any
analysis on the data collected from the study. The kinematic data collected from
the voluntary movements performed during therapy was used to calculate two
performance measures related to movement performance.
•
Accuracy
is the measure of how close the subject can get to a target while
reaching to this target. This is measured as the minimum distance between the
endpoint of the arm and the target location during the reaching movement. In
addition to the magnitude of the distance we also calculate the direction of this
error in term of the direction cosine.
•
Smoothness
is a measure of temporal coordination in a movement. Many
different techniques for quantifying movement smoothness can be found in the
current rehabilitation robotics literature. In our analysis we used five different
metrics to calculate the smoothness of a movement -
(1) Mean Jerk Metric (Rohrer
et al.
(2002))
