Page 109 - Concise Encyclopedia of Robotics

spacing, and therefore the capacitance, between the two plates. A direct-
current (DC) voltage is applied to the plates, as shown.As the capacitance
changes between the plates, the electric field between them fluctuates.
This produces variations in the current through the primary winding of
the transformer. Audio signals appear across the secondary winding.
In “speaker mode,”currents in the transformer produce changes in the
voltage between the plates. This change results in electrostatic force fluc-
tuations, pulling and pushing the flexible plate in and out. The motion of
the flexible plate produces sound waves. Empirical Design
Electrostatic transducers can be used in most applications where other
types of transducers are employed. This includes speech recognition and
speech synthesis systems. Advantages of electrostatic transducers include
light weight and excellent sensitivity.They can also work with small electric
currents. Compare DYNAMIC TRANSDUCER and PIEZOELECTRIC TRANSDUCER.
See also SPEECH RECOGNITION and SPEECH SYNTHESIS.
EMBEDDED PATH
An embedded path is a means of guiding a robot along a specific route.
The automated guided vehicle (AGV) employs this scheme.
One common type of embedded path is a buried, current-carrying
wire. The current in the wire produces a magnetic field that the robot can
follow. This method of guidance has been suggested as a way to keep a car
on a highway, even if the driver does not pay attention. The wire needs a
constant supply of electricity for this guidance method to work. If the
current is interrupted for any reason, the robot will lose its way.
Alternatives to wires, such as colored paints or tapes, do not need a
supply of power, and this gives them an advantage. Tape is easy to remove
and put somewhere else; this is difficult to do with paint, and practically
impossible with wires embedded in concrete. Compare EDGE DETECTION.
See also AUTOMATED GUIDED VEHICLE.
EMPIRICAL DESIGN
Empirical design is an engineering technique in which experience and
intuition are used in addition to theory. The process is largely trial
and error. The engineer starts at a logical point, based on theoretical
principles, but experimentation is necessary in order to get the device or
system to work just right.
Robots are ideally suited to empirical design techniques. An engineer
cannot draw up plans for a robot, no matter how detailed or painstaking
the drawing-board process might be, and expect the real machine to work
perfectly on the first trial.A prototype is built and tested, noting the flaws.
The engineer goes back to the drawing board and revises the design.
Sometimes it is necessary to start all over from scratch; more often, small

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