APG AGV-1000 Collision Avoidance user manual - Manual (Page 5)

Rev. A3, 10/08 AGV-1000
5
Automation Products Group, Inc.
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• Understanding Ultrasonics
Ultrasonic sensors measure distance
using a transducer to send out ultrasonic
bursts. Each burst contains a series of 1-20
pulsed sound waves that emit in the shape
of a cone, reflect off the target, and are
received by the sensor. The time required
for the sound burst to travel to and from
the target is converted into a distance
measurement by the sensor.
Ultrasonic sensing is affected by several
factors including the target surface,
distance, size, and angle. The following
considerations will help ensure the best
possible target conditions.
Surface
The ideal target surface is hard and smooth and perpendicular to the face of
the transducer. This surface will reflect a greater amount of signal than a soft,
sound wave absorbent surface. A target with poor sound wave reflection
characteristics will reduce the operating distance of the sensor and decrease its
accuracy.
detection
area
beam spread
low sensitivity
and
pulses
high sensitivity
and
pulses