Page 246 - Designing Sociable Robots

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Social Constraints on Animate Vision 227

closer. The believability of the robot’s behavior is closely tied to how well it can maintain
mutual regard with that person. This requires that the robot be more robust in detecting
people and their faces at a distance. The difference between having Kismet issue the calling
display while looking at a person’s face versus looking away from the person is enormous.
I find that a person will not interpret the calling display as a request for engagement unless
the robot is looking at their face when performing the display. It appears that the robot’s
gaze direction functions as a sort of social pointer—it says, “I’m directing this request and
sending this message to you.” For compelling social behavior, it’s very important to get
gaze direction right.
The perceptual performance can be improved by employing multi-resolution sampling on
the camera images. Regions of the wide field of view that indicate the presence of skin-tone
could be sampled at a higher resolution to see if that patch corresponds to a person. This
requires another stage of processing that is not in the current implementation. If promising,
the foveal camera could then be directed to look at that region to see if it can detect a face.
Currently the foveal camera only searches for eyes, but at these distances the person’s face
is too small to reliably detect eyes. A face detector would have to be written for the foveal
camera. If the presence of a face has been confirmed, then this target should be passed to the
attention system to maintain this region as the target for the duration of the calling behavior.
Other improvements to the visual system were discussed in chapter 6. These would also
benefit interaction with humans.

12.9 Summary

Motor control for a social robot poses challenges beyond issues of stability and accuracy.
Motor actions will be perceived by human observers as semantically rich, regardless of
whether the imputed meaning is intended or not. This can be a powerful resource for facil-
itating natural interactions between robot and human, and places constraints on the robot’s
physical appearance and movement. It allows the robot to be readable—to make its behav-
ioral intent and motivational state transparent at an intuitive level to those it interacts with.
It allows the robot to regulate its interactions to suit its perceptual and motor capabilities,
again in an intuitive way with which humans naturally co-operate. And it gives the robot
leverage over the world that extends far beyond its physical competence, through social
amplification of its perceived intent. If properly designed, the robot’s visual behaviors can
be matched to human expectations and allow both robot and human to participate in natural
and intuitive social interactions.
I have found that different subjects have different personalities and different interaction
styles. Some people read Kismet’s cues more readily than others. Some people take longer