Intelligent Systems And Their Societies Walter Fritz

Robby and the Perceptual Control Theory (PCT)


The brain of Robby uses the spirit of the Perceptual Control Theory (Exterior link), created by William T. Powers, even though in describing the activity of the brain I use some words that are badly chosen from the point of view of the PCT, the main offender being "response rules".

The PCT states (using my words) that the objective of an intelligent system is expressed in concepts ("perceptions") and the system tries to make the present situation, expressed in concepts, equal to the objective.

Let's see how Robby's brain uses this:
It works with "concepts" and "response rules". Concepts are structures in Robby's memory having a label, for instance "10125" and a structure of several branches. Except for elementary sensations all branches are an enumeration of concepts and response rules. "Response rules" are a structure in memory, also having a label, for instance ""-10133", and a structure of several branches. The main branches are the present situation, expressed in concepts, an applicable activity, also expressed in concepts, and the evaluation; the approval or disapproval given by a person the last time the "response rule" was used. Since the main objective of Robby is to please persons, this "evaluation" guides the robot to making approved actions.
It is important to note that the same concept can appear in the "present situation" part or in the "applicable activity", part. In other words, both the situation and the activity are expressed as concepts derived from sensations, as perceptions. Let's see how this works. Robby's brain has a brain sensory area, a central brain and a brain motor area.

An example is the movement of Robby's limbs. When the central brain determines that an arm movement is needed, it sends the corresponding concept to the brain motor area. There the concept is decomposed into three concepts. One for the objective angle of lateral movement, one for the objective angle of movement to the front, and one for the objective angle of the elbow. These three are concepts that the brain sensory area created from sensations of angle (perceptions). The motor area then sends air impulses to the respective cylinders, until the angle sensed (perceived) is equal to the objective angle.

Here is another example. Robby can hear a series of flute tones. The brain sensory area makes a concept for each tone and a concept that includes, in one of the branches, the concepts of all the tones. When Robby learns to produce the series of tones, the central brain sends to the brain motor area the concept (the perception) for the series of sounds. This area then decomposes the concept into the three elementary concepts and produces them. Also here, the concept for a sound heard is the same as the concept for a sound produced.

A further application of PCT in Robby probably will be the making of plans, but this is not yet worked out in detail.

So we can see, that the output of Robby is related to the input. And the output is produced using an objective that is a perception concept.


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Last Edited 25 April 2013 / Walter Fritz
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