Braitenberg Vehicles
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A Braitenberg vehicle is a concept conceived in a
thought experiment A thought experiment is a hypothetical situation in which a hypothesis, theory, or principle is laid out for the purpose of thinking through its consequences. History The ancient Greek ''deiknymi'' (), or thought experiment, "was the most anc ...
by the
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-
Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...
n
cyberneticist A cyberneticist or a cybernetician is a person who practices cybernetics. Heinz von Foerster once told Stuart Umpleby that Norbert Wiener preferred the term "cybernetician" rather than "cyberneticist", perhaps because Wiener was a mathematician ...
Valentino Braitenberg Valentino Braitenberg (or ''Valentin von Braitenberg''; 18 June 1926 – 9 September 2011) was an Italian neuroscientist and cyberneticist. He was former director at the Max Planck Institute for Biological Cybernetics in Tübingen, Germany. His ...
. The book models the animal world in a minimalistic and constructive way, from simple reactive behaviours (like
phototaxis Phototaxis is a kind of taxis, or locomotory movement, that occurs when a whole organism moves towards or away from a stimulus of light. This is advantageous for phototrophic organisms as they can orient themselves most efficiently to receive ...
) through the simplest vehicles, to the formation of concepts, spatial behaviour, and generation of ideas. For the simplest vehicles, the motion of the vehicle is directly controlled by some sensors (for example photo cells). Yet the resulting behaviour may appear complex or even intelligent.


Mechanism

A Braitenberg vehicle is an agent that can autonomously move around based on its sensor inputs. It has primitive
sensors A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends ...
that measure some stimulus at a point, and wheels (each driven by its own motor) that function as
actuators An actuator is a component of a machine that is responsible for moving and controlling a mechanism or system, for example by opening a valve. In simple terms, it is a "mover". An actuator requires a control device (controlled by control signal) an ...
or effectors. In the simplest configuration, a sensor is directly connected to an effector, so that a sensed signal immediately produces a movement of the wheel. Depending on how sensors and wheels are connected, the vehicle exhibits different behaviors (which can be goal-oriented). This means that, depending on the sensor-motor wiring, it appears to strive to achieve certain situations and to avoid others, changing course when the situation changes.Braitenberg, V. (1984). Vehicles: Experiments in synthetic psychology. Cambridge, MA: MIT Press. The connections between sensors and actuators for the simplest vehicles (2 and 3) can be
ipsilateral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
or
contralateral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
, and excitatory or inhibitory, producing four combinations with different behaviours named fear, aggression, liking, and love. These correspond to biological positive and negative taxesFraenkel, G. S., and Gunn,D.L. (1961). "The orientation of animals. Kineses, taxes and compass reactions". Dover Publications present in many animals species.


Examples

The following examples are some of Braitenberg's simplest vehicles.


Vehicle 1 - Getting Around

The first vehicle has one sensor (e.g. a temperature detector) that directly stimulates its single wheel in a directly proportional way. The vehicle moves ideally in one dimension only and can stand still or move forward at varying speed depending on the sensed temperature. When forces like asymmetric friction come into play, the vehicle could deviate from its straight line motion in unpredictable ways akin to Brownian motion. This behavior might be understood by a human observer as a creature that is 'alive' like an insect and 'restless', never stopping in its movement. The low velocity in regions of low temperature might be interpreted as a preference for cold areas.


Vehicle 2a

A slightly more complex agent has two (left and right) symmetric sensors (e.g. light detectors) each stimulating a wheel on the same side of the body. This vehicle represents a model of negative animal tropotaxis. It obeys the following rule: * More light right → right wheel turns faster → turns towards the left, away from the light. This is more efficient as a behavior to escape from the light source, since the creature can move in different directions, and tends to orient towards the direction from which least light comes. In another variation, the connections are negative or inhibitory: more light → slower movement. In this case, the agents move away from the dark and towards the light.


Vehicle 2b

The agent has the same two (left and right) symmetric sensors (e.g. light detectors), but each one stimulating a wheel on the other side of the body. It obeys the following rule: * More light left → right wheel turns faster → turns towards the left, closer to the light. As a result, the robot follows the light; it moves to be closer to the light.


Behavior

In a complex environment with several sources of stimulus, Braitenberg vehicles will exhibit complex and dynamic behavior. Depending on the connections between sensors and actuators, a Braitenberg vehicle might move close to a source, but not touch it, run away very fast, or describe circles or figures-of-eight around a point. This behavior is undoubtedly goal-directed, flexible and adaptive, and might even appear to be intelligent, the way some minimal intelligence is attributed to a cockroach. Yet, the functioning of the agent is purely mechanical, without any information processing or other apparently cognitive processes. Analog robots, such as those used in the
BEAM robotics BEAM robotics (from biology, electronics, aesthetics and mechanics) is a style of robotics that primarily uses simple analogue circuits, such as comparators, instead of a microprocessor in order to produce an unusually simple design. While not as ...
approach, often utilise these sorts of behaviors.


See also

*
BEAM robotics BEAM robotics (from biology, electronics, aesthetics and mechanics) is a style of robotics that primarily uses simple analogue circuits, such as comparators, instead of a microprocessor in order to produce an unusually simple design. While not as ...
*
Turtle (robot) Turtles are a class of educational robots designed originally in the late 1940s (largely under the auspices of researcher William Grey Walter) and used in computer science and mechanical engineering training. These devices are traditionally built l ...
* Unicycle cart


References

;Notes *Lambrinos, D., Scheier, Ch. (1995). tp://ftp.ifi.unizh.ch/pub/institute/ailab/techreports/95.10.ps.gz Extended braitenberg architectures Technical Report AI Lab no. 95.10, Computer Science Department, University of Zurich. * Headleand, Chris, Llyr Ap Cynedd, and William J. Teahan. "Berry Eaters: Learning Colour Concepts with Template Based Evolution Evaluation." ALIFE 14: The Fourteenth Conference on the Synthesis and Simulation of Living Systems. Vol. 14. {{refend


External links


Valentino Braitenberg's homepageA software Braitenberg vehicle simulatorAnother Braitenberg vehicle simulator
lets you play around with different settings, vehicles and sources
An Apple Playground on Braitenberg Vehicles
an APPLE playground in SWIFT language which implements some Braitenberg vehicles, it lets experiment in a very interactive way. Cybernetics BEAM robotics Thought experiments