Figure 1.
Static pointing task performed with a hand-held tool.
The tool is grasped at a fixed position , at distance
from the tool tip
. The pose
of the hand-held tool, with respect to a fixed frame
, can be specified as the position
and orientation
of a moving frame
attached to the tool at the gripping point.
Figure 2.
Example of configuration manifold.
Figure 3.
Components of the 3D position, in spatial frame coordinates, of the stylus tip () for one representative trial.
The ‘ * ’ marking the minima correspond to the positions furthest away from the target. The thick solid lines are the data of interest, within 5 seconds before and after the midpoint between two minima.
Figure 4.
Variance per dof in the nullspace () and its orthogonal complement (
) for all 20 trials of a representative subject.
Figure 5.
Power spectral density for each velocity component of a representative subject.
Figure 6.
Average UCM components for each subject in Exp I (left, supported arm) and Exp II (right, unsupported arm).
For both experimental conditions, each subject shows a statistically significant difference () between the UCM components. Vertical lines represent the standard errors.
Figure 7.
UCM ratio for seven subjects for the two experimental conditions, Exp I and Exp II (top).
Bottom figures show the ratio between Exp II and Exp I (left) and similarly for
(right). The horizontal line marks the unitary ratio (i.e. no difference in the variance in position between Exp II and Exp I). Vertical lines represent the standard errors. Statistically significant differences are highlighted for
(*), for
(**), and for
(***).
Figure 8.
Variance at and
in Exp I (left) and Exp II (right).
Vertical lines represent the standard errors. Statistically significant differences are highlighted for (*), for
(**), and for
(***).
Figure 9.
Ratio of position variance ratio () for each subject in both experimental conditions (Exp I and Exp II) (top).
Bottom figures show the ratio between Exp II and Exp I (left) and similarly for
(right). The horizontal line marks the unitary ratio (i.e. no difference in the variance in position between Exp II and Exp I). Vertical lines represent the standard errors. Statistically significant differences are highighted for
(*), for
(**), and for
(***).