Page 95 - Introduction to AI Robotics

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3 Biological Foundations of the Reactive Paradigm
Releaser

BEHAVIOR

Sensory Pattern of
Input Motor Actions

Figure 3.4 Innate Releasing Mechanism as a process with behaviors.

ior gets turned on and off. The releaser acts as a control signal to activate a
behavior. If a behavior is not released, it does not respond to sensory inputs
and does not produce motor outputs. For example, if a baby arctic tern isn’t
hungry, it doesn’t peck at red, even if there is a red beak nearby.
Another way to think of IRMs is as a simple computer program. Imagine
the agent running a C program with a continuous while loop. Each execu-
tion through the loop would cause the agent to move for one second, then
the loop would repeat.
enum Releaser={PRESENT, NOT_PRESENT};
Releaser predator;
while (TRUE)
{
predator = sensePredators();
if (predator == PRESENT)
flee();
}

In this example, the agent does only two things: sense the world and then
flees if it senses a predator. Only one behavior is possible: flee. flee is
released by the presence of a predator. A predator is of type Releaser and
has only two possible values: it is either present or it is not. If the agent does
not sense the releaser for the behavior, the agent does nothing. There is no
“default” behavior.
This example also shows filtering of perception. In the above example, the
agent only looks for predators with a dedicated detection function, sense-
Predators(). The dedicated predator detection function could be a spe-
cialized sense (e.g., retina is sensitive to the frequency of motions associated