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Bots / The Ultimate Palm Robot/ Mukhar & Johnson / 222880-6 / Chapter 2

32 The Ultimate Palm Robot

For the BrainStem controller, Acroname is the one and only source. If, in-
stead, you want to experiment with the SV203 controller, you can get it from
Acroname, from the manufacturer (that’s Pontech, at www.pontech.com), or
from Jameco Electronics at www.jameco.com.

See Me, Feel Me
To get information about its environment and the objects around it, the PPRK
uses sensors. To be precise, the original PPRK used infrared rangers. These
rangers transmit an infrared signal from one sensor; if an object reflects the
signal, the return signal is received at another sensor. Using the reflected sig-
nal, the distance to a nearby object can be calculated.
The PPRK uses Sharp GP2D12 infrared rangers, seen in Figure 2-5. This
ranger can detect objects that are between 10 cm and 80 cm (approximately 4
inches to 31.5 inches) away from the sensor. Sharp Microelectronics makes a
number of different IR rangers. You can find detailed information about the
rangers at www.sharpsma.com/sma/products/opto/optical_systems.htm.

Figure 2-5
The Sharp GP2D12 sensor transmits signals from an infrared LED and receives the return signal on the receiver.
When the sensor is positioned so that the white connector is toward the bottom, the transmitter is the LED on
the left and the receiver is the sensor on the right.

The Sharp GP2D12 ranger determines distance to objects by a technique
known as triangulation. If you examine Figure 2-5, you’ll see that a small dis-
tance separates the transmitter and receiver. By measuring the transmit- and
receive- angles of the reflected IR signal, the ranger can calculate the distance
to the object that reflected the signal.

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