A Braitenberg vehicle is a concept conceived in a thought experiment by the Italian-Austrian cyberneticist Valentino Braitenberg to illustrate in an evolutive way the abilities of simple agents. The vehicles represent the simplest form of behavior based artificial intelligence or embodied cognition, i.e. intelligent behavior that emerges from sensorimotor interaction between the agent and its environment, without any need for an internal memory, representation of the environment, or inference.
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A Braitenberg vehicle is an agent that can autonomously move around. It has primitive sensors (measuring some stimulus at a point) and wheels (each driven by its own motor) that function as actuators or effectors. A sensor, in the simplest forms, 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 it appears to strive to achieve certain situations and to avoid others, changing course when the situation changes.[1]
The following examples are some of Braitenberg's simplest vehicles.
A first agent has one light-detecting sensor that directly stimulates its single wheel, implementing the following rules:
This behavior can be interpreted as a creature that is afraid of the light and that moves fast to get away from it. Its goal is to find a dark spot to hide.
A slightly more complex agent has two light detectors (left and right) each stimulating a wheel on the same side of the body. It obeys the following rule:
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.
In a complex environment with several sources of stimulus, Braitenberg vehicles will exhibit a 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, or, the opposite, it could run away very fast, or describe circles around a point, or figures-of-eight. 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.
Often, BEAM robotics implements these sorts of behaviors.