Page 36 - Concise Encyclopedia of Robotics

Azimuth-Range Navigation
A classical azimuth-range navigation system is conventional radar, which
consists of a transmitter, a highly directional antenna, a receiver, and a
display. The transmitter produces EM microwave pulses that are propa-
gated in a narrow beam. The EM waves strike objects at various distances.
The greater the distance to the target, the longer is the delay before the
echo is received. The transmitting antenna is rotated so that all azimuth
bearings can be observed.
The basic configuration of an azimuth-range scheme is shown in the
illustration. The robot is at the center of the display. Azimuth bearings are
indicated in degrees clockwise from true north,and are marked around the
perimeter. The distance, or range, is indicated by the radial displacement.
Some azimuth-range systems can detect changes in the frequencies
of returned EM or acoustic pulses resulting from Doppler effect. These
data are employed to measure the speeds of approaching or receding
objects. The robot controller can use this information, along with the
position data afforded by the azimuth-range scheme, to navigate in
complex environments.
See also RADAR.

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