306
Biologically Inspired Robotics
This setup is well suited for static experiments, but if the robot is mobile, a
wireless link is needed. Therefore, we added the option to transmit the scene
view video as well as the motor commands over a WiFi connection at the cost
of a higher overall latency.
In the Results section we will report on the measured latencies for each method.
A short total delay, preferably at only a fraction of the time of human reactions, is
of particular importance for future experiments, because we intend to manipulate the teleoperation channel by introducing, for example, additional systematic
delays (see flash in Figure 16.1) and test their effects on interaction performance.
Therefore, the baseline delay needs to be as close to zero as possible.
16.3 Discussion and Results
We have developed a novel experimental platform for Wizard-of-Oz evaluations of biomimetic properties of active vision systems for robots. The main
question was how well this platform is suited for the envisioned types of
experiments. Evidently, human eye movements have to be replicated with
sufficient fidelity, and the combination of an eye tracker with camera motion
devices has to fulfill rigid real-time requirements. In this section we quantify
how well the overall design meets these requirements.
16.3.1 Handling of Eye Vergence
One fundamental challenge was the question of how to handle vergence eye
movements, which occur when points at different depths are fixated on. Given
the geometry of the robot, in particular the eye positions and the kinematics
of the head, it is possible to direct both lines of sight at one specific point in
three-dimensional space. This poses a problem in the Wizard-of-Oz scenario,
where the wizard is only able to look at a flat surface (i.e., his screen). If the
distance to the fixated object is sufficiently large (>6 m), the eyes are nearly
parallel, but the nearer the fixation is, the more eye vergence becomes noticeable. For now, we have resolved this problem by preselecting the distance at
which the wizard fixates. This is an adequate solution for dialog scenarios,
where the robot interacts with one or a few persons at roughly the same distance. If the scene is static and more control is needed, regions of interest on
the wizard’s monitor could be mapped to distinct distances. To reproduce
eye vergence in its entirety, though, a binocular eye tracker combined with a
stereoscopic monitor or head-mounted display would be needed.
16.3.2 Camera Motion Device
The piezo actuators chosen for the new camera motion device proved particularly beneficial in the overall design. They are backlash free and each piezo
Biologically Inspired Robotics
This setup is well suited for static experiments, but if the robot is mobile, a
wireless link is needed. Therefore, we added the option to transmit the scene
view video as well as the motor commands over a WiFi connection at the cost
of a higher overall latency.
In the Results section we will report on the measured latencies for each method.
A short total delay, preferably at only a fraction of the time of human reactions, is
of particular importance for future experiments, because we intend to manipulate the teleoperation channel by introducing, for example, additional systematic
delays (see flash in Figure 16.1) and test their effects on interaction performance.
Therefore, the baseline delay needs to be as close to zero as possible.
16.3 Discussion and Results
We have developed a novel experimental platform for Wizard-of-Oz evaluations of biomimetic properties of active vision systems for robots. The main
question was how well this platform is suited for the envisioned types of
experiments. Evidently, human eye movements have to be replicated with
sufficient fidelity, and the combination of an eye tracker with camera motion
devices has to fulfill rigid real-time requirements. In this section we quantify
how well the overall design meets these requirements.
16.3.1 Handling of Eye Vergence
One fundamental challenge was the question of how to handle vergence eye
movements, which occur when points at different depths are fixated on. Given
the geometry of the robot, in particular the eye positions and the kinematics
of the head, it is possible to direct both lines of sight at one specific point in
three-dimensional space. This poses a problem in the Wizard-of-Oz scenario,
where the wizard is only able to look at a flat surface (i.e., his screen). If the
distance to the fixated object is sufficiently large (>6 m), the eyes are nearly
parallel, but the nearer the fixation is, the more eye vergence becomes noticeable. For now, we have resolved this problem by preselecting the distance at
which the wizard fixates. This is an adequate solution for dialog scenarios,
where the robot interacts with one or a few persons at roughly the same distance. If the scene is static and more control is needed, regions of interest on
the wizard’s monitor could be mapped to distinct distances. To reproduce
eye vergence in its entirety, though, a binocular eye tracker combined with a
stereoscopic monitor or head-mounted display would be needed.
16.3.2 Camera Motion Device
The piezo actuators chosen for the new camera motion device proved particularly beneficial in the overall design. They are backlash free and each piezo