This is about Sensors, Sensors’ Classification, Vision System, Steps in Vision Sensing, Image Acquisition, Ultrasonic Sensors
• As the name indicates, ultrasonic sensors measure distance by using ultrasonic
waves.
The sensor head emits an ultrasonic wave and receives the wave reflected back
from the target.
• Ultrasonic Sensors measure the distance to the target by measuring the time
between the emission and reception.
• Distance calculation
• The distance can be calculated with the following formula:
• Distance L = 1/2 × T × C
where L is the distance, T is the time between the emission and reception,
and C is the sonic speed.
(The value is multiplied by 1/2 because T is the time for go-and-return
distance.)
Features
• [Transparent object detectable]
Since ultrasonic waves can reflect off a glass or liquid surface and return to the sensor head, even
transparent targets can be detected.
• [Resistant to mist and dirt]
Detection is not affected by accumulation of dust or dirt.
• [Complex shaped objects detectable]
Presence detection is stable even for targets such as mesh trays or springs.
How Ultrasonic Sensors Work?
•Ultrasonic sound vibrates at a frequency above the range of human
hearing.
• Transducers are the microphones used to receive and send the
ultrasonic sound.
•Ultrasonic sensors, like many others, use a single transducer to send a
pulse and to receive the echo. The sensor determines the distance to
a target by measuring time lapses between the sending and receiving
of the ultrasonic pulse.
Ultrasonic Sensors
• Ultrasound can be used for measuring wind speed and direction
(anemometer), tank or channel fluid level, and speed through air or water.
• It generates sound waves in the ultrasonic range, above 18 kHz, by turning
electrical energy into sound, then upon receiving the echo turn the sound
waves into electrical energy which can be measured and displayed.
• The technology is limited by the shapes of surfaces and the density or
consistency of the material.
• Foam, in particular, can distort surface level readings.
• This technology, as well, can detect approaching objects and track
their positions.
• Ultrasonic transducers convert AC into ultrasound, as well as the reverse.
• Ultrasonic, typically refers to piezoelectric transducers or capacitive
transducers.
• Piezoelectric crystals change size and shape when a voltage is applied; AC
voltage makes them oscillate at the same frequency and produce ultrasonic
sound.
• Capacitive transducers use electrostatic fields between a conductive
diaphragm and a backing plate.
Selection of Sensors
The most common optical sensor options are photoelectric—diffuse, reflective, and through beam. Laser sensors and fiber-optic sensing units also fall under the optical sensor category. Photoelectric sensors are mostly presence sensors.
5. Ultrasonic Sensors
• As the name indicates, ultrasonic sensors measure distance by using ultrasonic
waves.
The sensor head emits an ultrasonic wave and receives the wave reflected back
from the target.
• Ultrasonic Sensors measure the distance to the target by measuring the time
between the emission and reception.
6. Ultrasonic Sensors
• Distance calculation
• The distance can be calculated with the following formula:
• Distance L = 1/2 × T × C
where L is the distance, T is the time between the emission and reception,
and C is the sonic speed.
(The value is multiplied by 1/2 because T is the time for go-and-return
distance.)
7. Ultrasonic Sensors
Features
• [Transparent object detectable]
Since ultrasonic waves can reflect off a glass or liquid surface and return to the sensor head, even
transparent targets can be detected.
• [Resistant to mist and dirt]
Detection is not affected by accumulation of dust or dirt.
• [Complex shaped objects detectable]
Presence detection is stable even for targets such as mesh trays or springs.
8. How Ultrasonic Sensors Work?
•Ultrasonic sound vibrates at a frequency above the range of human
hearing.
•Transducers are the microphones used to receive and send the
ultrasonic sound.
•Ultrasonic sensors, like many others, use a single transducer to send a
pulse and to receive the echo. The sensor determines the distance to
a target by measuring time lapses between the sending and receiving
of the ultrasonic pulse.
10. Ultrasonic Sensors
• Ultrasound can be used for measuring wind speed and direction
(anemometer), tank or channel fluid level, and speed through air or water.
• It generates sound waves in the ultrasonic range, above 18 kHz, by turning
electrical energy into sound, then upon receiving the echo turn the sound
waves into electrical energy which can be measured and displayed.
11. Ultrasonic Sensors
•The technology is limited by the shapes of surfaces and the density or
consistency of the material.
•Foam, in particular, can distort surface level readings.
•This technology, as well, can detect approaching objects and track
their positions.
12. Ultrasonic Sensors
• Ultrasonic transducers convert AC into ultrasound, as well as the reverse.
• Ultrasonic, typically refers to piezoelectric transducers or capacitive
transducers.
• Piezoelectric crystals change size and shape when a voltage is applied; AC
voltage makes them oscillate at the same frequency and produce ultrasonic
sound.
• Capacitive transducers use electrostatic fields between a conductive
diaphragm and a backing plate.
