June 25, 2012 12:33 PSP Book - 9in x 6in 05-Junichi-Takeno-c05
Chapter 5
Professor Valentino Braitenberg’s
Vehicles
Valentino Braitenberg was director of the Max Planck Institute
for Biological Cybernetics, Germany, where, using small robots
equipped with sensors and drive motors, he studied robots with a
mind from the standpoint of functionalism.
In brief, functionalism is a method to try to understand
something by analyzing the function inherent in the thing to the
extent possible by human wisdom. What is important in this
definition is that the understanding is limited to the range possible
by human wisdom.
Braitenberg was one of the pioneering researchers of robotics,
and he designed robots by transmitting information directly from
sensors to drive motors. He invented many vehicles, each with suc-
cessive improvements, and showed that a wide range of robots from
toy-level to a self-conscious robot could be made using very simple
components (Braitenberg, 1987). He was a forerunner in research
on evolutionary robotics and embodied cognitive science, which
are currently very actively studied in the field of robotics. Many of
the methodologies adopted by these researchers had already been
suggested by Braitenberg. This fact is indeed marvelous.
Creation of a Conscious Robot: Mirror Image Cognition and Self-Awareness
Junichi Takeno
Copyright
c
2013 Pan Stanford Publishing Pte. Ltd.
ISBN 978-981-4364-49-2 (Hardcover), 978-981-4364-50-8 (eBook)
www.panstanford.com
June 25, 2012 12:33 PSP Book - 9in x 6in 05-Junichi-Takeno-c05
72 Professor Valentino Braitenberg’s Vehicles
For instance, the idea of a modern evolutionary robot is the
same as what Braitenberg called a Darwinian robot. A robot that
expresses the feelings of “like and hate” using the connections
between the sensors of artificial neural networks and drive
motors, a phenomenon that would later be called emergence,
was also conceived by Braitenberg. I believe that his research
should be further evaluated. This underestimation seems to be
due to the argument that “he sides with functionalism and
admits the existence of representation,” because many scientists
favor the behavioristic stance. His vehicle robots are introduced
now.
5.1 Braitenberg’s Vehicles 1 Through 4
Braitenberg’s vehicle 1 has the simplest structure. It consists of
asensorandadrivemotor.Thesensorandthedrivemotorare
connected by an artificial nerve. The motor drives a wheel located
at the rear of the robot (Fig. 5.1a). The robot is just like a small
cell swimming with a flagellum. Vehicle 1 does not have a rudder.
When it runs, it always runs straight ahead. A robot is almost
always asymmetrical, so that the robot may make a slight turn.
The sensor can be any sensor. Let us assume a temperature sensor.
The sensor emits zero signals at the absolute zero point. At other
temperatures, the sensor issues stronger signals as the temperature
rises.
The signal is transmitted to the drive motor via the artificial
nerve. The motor’s speed (rotation) increases or decreases with the
strength of the signal. Put this robot in a space, and it detects the
ambient temperature and starts running at a speed corresponding
to the detected temperature. The robot slows down in areas with
lower temperatures.
To a casual onlooker, this robot looks like a simple life form
such as an amoeba that becomes more active in places of high
temperature.
When the reaction property of the artificial nerve is designed as
shown in Figure 5.1c, the artificial life will be activated at a certain
temperature.
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Braitenberg’s Vehicles 1 Through 4 73
(a)
(b)
(c)
Figure 5.1. Braitenberg’s Vehicle 1.
Braitenberg’s vehicle 2 has two sensors that are connected to two
respective motors. There are two types of artificial nerves: parallel
(Fig. 5.2(1)) and crossed (Fig. 5.2(3)). The plus and minus signs (+
and −) indicate the property of the artificial nerve. For a plus (+)
sign, the output of the nerve increases with increasing output signals
of the sensor (facilitation). For a minus (–) sign, the output of the
nerve decreases with increasing output signals (inhibition). Only the
minus sign is shown here, but there should be no confusion caused
with the plus sign omitted.
Let us assume that this robot is equipped with light sensors. The
robot in the figure, with a light just in front of it, will go straight
toward the light with its speed increasing until it crashes into the
bulb and destroys it (Fig. 5.2(2)a).
If the light is not just in front of the robot, the sensor closer to the
light is activated more than the other sensor, and the relevant motor
increases its speed. As a result, the robot follows a path to avoid the
light (Fig. 5.2(2)b). If the robot sees the light just in front of it again,
the robot will rush toward the light.
The robot shown in Fig. 5.2(2) is a fearful and aggressive type
since it avoids light but suddenly attacks it depending on the
position of the light.
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74 Professor Valentino Braitenberg’s Vehicles
(1)
(2)
(4)
(3)
Figure 5.2. Braitenberg’s Vehicle 2.
The robot shown in Fig. 5.2(3) is identical to the robot shown in
Fig. 5.2(1) except that the nerves are crossed. This robot also goes
straight ahead and collides with the light if the light is just in front of
it. If the light is on the left side of the robot, the drive motor on the
right side increases its speed, an opposite action because the nerves
are crossed, and the robot turns toward the light.
Like a guided missile, the robot rushes at the light as if it were
being sucked into it (Figure 5.2(4)). This is an aggressive-type robot.
The activation of the nerves is inhibited in vehicle 3.
In Fig. 5.3(1), the right and left nerves are in parallel, and their
activation is inhibited (note the minus sign). This robot, placed at
an angle to the light, slows down as it draws closer to the light and
finally stops because the sensor on the side facing the light emits a
higher signal than the other sensor and speed of the motor on the
side facing the light slows down (remember the nerves are parallel
and inhibited). The motor on the side away from the light runs faster
than the motor on the side facing the light, and thus the robot turns
itself toward the light (Fig. 5.3(2)). Both motors slow down as the
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Braitenberg’s Vehicles 1 Through 4 75
(1)
(2)
(4)
(3)
Figure 5.3. Braitenberg’s Vehicle 3.
robot approaches the light, until the robot stops before reaching the
light (Fig. 5.3(2)a).
The robot shown in Fig. 5.3(3) has crossed nerves and the signals
are inhibited. If the light is just in front of the robot, the robot goes
straight toward the light while its speed continues decreasing, and
it stops before reaching the light (Fig. 5.3(4)b). Otherwise, the robot
turns away from the light while slowing down and gains speed as it
moves away from the light (Fig. 5.3(4)c).
The robots that slow down and stop near the light may be said to
be “affectionate” toward the light, whereas the robot shown in Fig.
5.3(3) is “fickle” because in most cases, it visits the light here and
there but quickly runs away.
Braitenberg’s vehicle 4 moves around the light in various
patterns, reflecting the reaction properties of the artificial nerves
Braitenberg devised.
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