Page 74 - Designing Sociable Robots

breazeal-79017 book March 18, 2002 14:1

The Physical Robot 55

Kismet’s vision system is implemented on a network of nine 400 MHz commercial PCs
running the QNX real-time operating system. The PCs are connected together via 100 MB
Ethernet. There are frame grabbers and video distribution amplifiers to distribute multiple
copies of a given image with minimal latencies. The cameras that are used to compute stereo
measures are externally synchronized.
The Auditory System
The caregiver can influence the robot’s behavior through speech by wearing a small un-
obtrusive wireless microphone. This auditory signal is fed into a 500 MHz PC running
Linux. The real-time, low-level speech processing and recognition software was developed
at MIT by the Spoken Language Systems Group. These auditory features are sent to a dual
450 mHz PC running Windows NT. The NT machine processes these features in real-time
to recognize the spoken affective intent of the caregiver. The Linux and NT machines are
connected via 100 MB Ethernet to a shared hub and use CORBA for communication.

The Expressive Motor System
Kismet is able to display a wide assortment of facial expressions that mirror its affec-
tive state, as well as produce numerous facial displays for other communicative purposes
(Breazeal & Scassellati, 1999b). Figure 5.4 illustrates a few examples. All eight expres-
sions, and their accompanying vocalizations, are shown in the second demonstration on the
included CD-ROM. Fourteen of the face actuators are Futaba micro servos, which come in
a lightweight and compact package. Each ear has two degrees of freedom that enable each
to elevate and rotate. This allows the robot to perk its ears in an interested fashion, or fold
them back in a manner reminiscent of an angry animal. Each eyebrow has two degrees of
freedom that enable each to elevate and to arc toward and away from the centerline. This
allows the brows to furrow in frustration, or to jolt upward in surprise. Each eyelid can open
and close independently, allowing the robot to wink an eye or blink both. The robot has four

Figure 5.4
Some example facial expressions that illustrate the movement of Kismet’s facial features. From left to right they
correspond to expressions for sadness, disapproval, happiness, and surprise.