Page 158 - Robots Androids and Animatrons : 12 Incredible Projects You Can Build

If you want to experiment, begin by using the pulsout and pwm
commands to vary the DC motor speed.
Neural sensors (logic)
With a small amount of programming, we can change our fuzzy logic
sensors (CdS photocells) to neural sensors. Neural networks are an
expansive topic. We will limit ourselves to one small example. For
those who want to further pursue study into neural networks, I
recommend a book I’ve written titled Understanding Neural
Networks (Prompt, Indianapolis, 1998, ISBN 0-7906-1115-5).

To create neural sensors, we will take the numeric resistive reading
from each sensor, multiply it by a weight factor, and then sum the
results. The results are then compared to a tri-level threshold value
(see Fig. 6.36).
Thus our small program and sensors are performing all the func-
tions expected in a neural network. We may even be pioneering a
neural first, by applying a multivalue threshold scheme. Do multi-
value thresholds exist in nature (biological systems)? The answer
is yes. For instance, an itch is an extremely low level of pain, and
the sensation of burning can be felt when sensing something ice
cold or hot. 137

6.36 Schematic of simple tri-level neuron

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