Page 23 - Human Inspired Dexterity in Robotic Manipulation

Digital Hand: Interface Between the Robot Hand and Human Hand 19

and hand thickness. A boundary family is used to represent a possible range
of inter-individual variation in a population under the multi-dimensional
situation.
The boundary family of hand dimensions is calculated using an anthro-
pometric database of the target population. The information carried by hand
dimensions correlated with each other is compressed using a principal com-
ponent analysis (PCA). The first two principal components carrying the
largest percentage of the total variance are used to draw a scatter diagram
of subjects and a probability ellipse that contains 95% or 99% of the subjects.
The boundary family consists of nine members located on this ellipse [16].
One member is located at the center of the ellipse and eight members are
located on the boundary of the ellipse; at the crossing points of the ellipse
and the x-axis (PC 1) or y-axis (PC 2), or the crossing points of the ellipse
and lines with the slope of SD_PC2/SD_PC1, where SD_PC1 and
SD_PC2 are standard deviations of PC1 and PC2 scores, respectively.
Fig. 2.3 shows the probability ellipse for Japanese adults including males
and females. In this figure, five representative models are also shown.
Hand dimensions of the nine members of the boundary family are cal-
culated from their PC scores and eigenvectors. Representative hand models
are synthesized by deforming the generic model using these calculated hand
dimensions [15]. Locations of joint centers of the representative hand models

Fig. 2.3 Probability ellipse of hand dimensions for Japanese adults, males, and females,
and five representative digital hand models from the boundary family.