Page 56 - Robot Builder's Bonanza

SENSING DEVICES 25

you use it every day when you press down on the brake pedal. Similarly, pneumatic power
uses air pressure to move linkages. Pneumatic systems are cleaner than hydraulic systems,
but, all things considered, they aren’t as powerful.
Both hydraulic and pneumatic systems must be pressurized to work, and this is commonly
done using a pump that’s driven by an electric or gas motor. Hydraulic and pneumatic systems
are harder and more expensive to implement, but they provide an extra measure of power.
With a few hundred dollars in surplus pneumatic cylinders, hoses, fittings, and other parts, you
could conceivably build a hobby robot that picks up chairs, bicycles, even people!
These alternative power sources aren’t covered here, but if you’re interested, check out the
local library for books on solar, hydraulic, and pneumatic systems.

Sensing Devices

Imagine a world without sight, sound, touch, smell, or taste. Without these senses, we’d be
nothing more than an inanimate machine, like the family car, the living room television, or that
guy who hosts the Channel 5 late- night movie. Our senses are an integral part of our lives.
The more senses a robot has, the more it can interact with its environment. That’s impor-
tant for the robot to go about its business on its own. Figure 2-13 shows how sensors form an
integral part of the robot.

TOUCH
The sense of touch is provided by mounting switches to the robot’s frame, so that it can detect
when it’s run into something— or something has run into it. Another way to register touch is
with a pressure sensor, which detects when a certain amount of force is exerted on it. You can
build your own inexpensive pressure sensors or buy them ready- made for a few dollars. See
Chapter 42, “Adding the Sense of Touch,” for details.

LIGHT AND SOUND

It’s easy to make a robot sensitive to light; in fact, these are among the least- expensive sen-
sors you can add to a robot. Chapter 44, “Robotic Eyes,” provides a number of plans for
giving sight to a robot. You can even connect a video camera and beam the picture from your
spybot to another room.
You can use light as a way to remotely communicate with your robot. Using a standard
infrared remote control, you can program your robot to watch for the special coded signals
that happen each time you press a button.
The same goes for sensitivity to sound. Sound is easy to detect. Find out more in Chap-
ter 46, “Making and Listening to Sound.”

SMELL AND TASTE
With some fairly inexpensive sensors, you can equip your bot to effectively smell for danger-
ous toxic gas, sniff around for smoke, sound the alarm if it detects the flame of a fire, or hit
the panic button if things get too hot. See Chapter 48, “Danger, Will Robinson!,” for some
ideas and hands- on projects on sensing fire, heat, flame, and gas.

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