298
Biologically Inspired Robotics
The basis for verbal communication has previously been implemented in
robotic systems. Speech recognition and synthesis are an accepted means of
human–machine interaction, used, for example, in call centers. For eye contact, however, there does not exist such a sophisticated infrastructure, yet.
In our work, we focus on the nonverbal part, in particular on eye and head
movements. Because a number of robotic vision systems already exist and
can be found in the literature, we will give a short overview of the state of
the art in this field.
16.1.1 State of the Art
The most obvious purpose a vision system fulfills is that of a sensor system for
visual perception. For this purpose, simple systems with fixed stereo cameras
can be used. Humanoid robots in this category include HRP-2 (Kaneko et al.
2004), Johnnie (Cupec, Schmidt, and Lorch 2005), and Justin (Ott et al. n.d.).
Robots can also use their eyes as a display for natural human–robot interaction. Eye movements are understood by any human and their meaning does
not have to be learned. The eyes must be moveable but do not have to provide
actual vision for the robot. Androids like ROMAN (Berns and Hirth 2006),
Geminoid HI-1 (Ishiguro and Nishio 2007), and Repliee R1/Q2 (Matsui et al.
2005; Minato et al. 2004) are included in this category. Ideally, the vision system
of the robot is used for both purposes. This is demanding, because the eyes
have to be fast and precise to minimize motion blur and their motions have
to be independent of each other to support vergence movements, even when
the head rotates around the line of sight (torsional movement). For human-like
foveated vision, often peripheral cameras are used, which are either moved
with the foveated cameras or are fixed. Cog (Brooks et al. 1999) and Kismet
(Breazeal 2003; Breazeal et al. 2000, 2001) from the Massachusetts Institute
of Technology (MIT) both support a moveable head with eyes that are able
to rotate around two independent vertical axes but with only one coupled
horizontal axis, which limits vergence movements (as long as the head is not
rolled). Whereas Cog has two cameras per eye for both foveal and peripheral
vision, Kismet has only moveable foveal vision, with two head-fixed peripheral
cameras. The SARCOS robots DB and CB at Advanced Telecommunications
Research Institute International (ATR) have biomimetic oculomotor control
(Shibata and Schaal 2001; Shibata et al. 2001; Ude, Gaskett, and Cheng 2006).
Domo (Edsinger-Gonzales and Weber 2004) uses only wide-angle cameras,
whereas ARMAR has foveal/peripheral vision. Other robots with active
vision are iCub (Beira et al. 2006) and WE-4RII (Miwa et al. 2004). Stand-alone
systems have been developed as well (Samson et al. 2006). There have also
been efforts to move from the foveal/peripheral camera pair to a more anthropomorphic eye (Samson et al. 2006). Apart from DB/CB none of the robots
implement two fully independent eyes, but they share at least one common
Biologically Inspired Robotics
The basis for verbal communication has previously been implemented in
robotic systems. Speech recognition and synthesis are an accepted means of
human–machine interaction, used, for example, in call centers. For eye contact, however, there does not exist such a sophisticated infrastructure, yet.
In our work, we focus on the nonverbal part, in particular on eye and head
movements. Because a number of robotic vision systems already exist and
can be found in the literature, we will give a short overview of the state of
the art in this field.
16.1.1 State of the Art
The most obvious purpose a vision system fulfills is that of a sensor system for
visual perception. For this purpose, simple systems with fixed stereo cameras
can be used. Humanoid robots in this category include HRP-2 (Kaneko et al.
2004), Johnnie (Cupec, Schmidt, and Lorch 2005), and Justin (Ott et al. n.d.).
Robots can also use their eyes as a display for natural human–robot interaction. Eye movements are understood by any human and their meaning does
not have to be learned. The eyes must be moveable but do not have to provide
actual vision for the robot. Androids like ROMAN (Berns and Hirth 2006),
Geminoid HI-1 (Ishiguro and Nishio 2007), and Repliee R1/Q2 (Matsui et al.
2005; Minato et al. 2004) are included in this category. Ideally, the vision system
of the robot is used for both purposes. This is demanding, because the eyes
have to be fast and precise to minimize motion blur and their motions have
to be independent of each other to support vergence movements, even when
the head rotates around the line of sight (torsional movement). For human-like
foveated vision, often peripheral cameras are used, which are either moved
with the foveated cameras or are fixed. Cog (Brooks et al. 1999) and Kismet
(Breazeal 2003; Breazeal et al. 2000, 2001) from the Massachusetts Institute
of Technology (MIT) both support a moveable head with eyes that are able
to rotate around two independent vertical axes but with only one coupled
horizontal axis, which limits vergence movements (as long as the head is not
rolled). Whereas Cog has two cameras per eye for both foveal and peripheral
vision, Kismet has only moveable foveal vision, with two head-fixed peripheral
cameras. The SARCOS robots DB and CB at Advanced Telecommunications
Research Institute International (ATR) have biomimetic oculomotor control
(Shibata and Schaal 2001; Shibata et al. 2001; Ude, Gaskett, and Cheng 2006).
Domo (Edsinger-Gonzales and Weber 2004) uses only wide-angle cameras,
whereas ARMAR has foveal/peripheral vision. Other robots with active
vision are iCub (Beira et al. 2006) and WE-4RII (Miwa et al. 2004). Stand-alone
systems have been developed as well (Samson et al. 2006). There have also
been efforts to move from the foveal/peripheral camera pair to a more anthropomorphic eye (Samson et al. 2006). Apart from DB/CB none of the robots
implement two fully independent eyes, but they share at least one common