The ultrasonic sensor measures the distance to targets through the air using non-contact technology. It is easy to use, reliable and economical. The principle of operation of this device is based on techniques used by various animals. The gadget provides accurate measurements in many challenging environments and unusual materials.
Content
- Features of work and history of invention
- Ultrasonic principle
- Device and technical characteristics
- Application and benefits
Features of work and history of invention
The ultrasonic transducer emits short, high-frequency sound pulses at regular intervals. They travel through the air at the speed of sound. If the pulses collide with an object, they are reflected back to the sensor in the form of echo signals. The device independently calculates the distance to the target based on the time interval between the emission of the signal and the receipt of the echo.
Since the distance to an object is determined by measuring the time of flight, and not by the intensity of the sound,
ultrasonic sensors are ideal for suppressing background noise. Almost all objects that reflect sound can be detected regardless of their color. Transparent materials or thin foils are also not a problem for ultrasonic waves, since the device is able to see through dust, air and ink mists. Even thin deposits on the sensory membrane do not impair its function.
The history of the invention of the ultrasonic sensor dates back to 1790, when Lazzaro Spallanzani first discovered that bats maneuver in flight using hearing rather than sight. Spallanzani conducted a series of experiments on bats, after which he came to the conclusion that they use sound and ears to navigate in complete darkness. He was a pioneer in the initial study of echolocation, although his research was limited to observation only.
Later, scientists turned to the study of sensory mechanisms. In the 1930s, researcher Donald Griffin was the first to confirm that bats move by using sound to navigate, and discovered the secret of their remarkable ability to move in the dark. The animals were found to emit ultrasonic sounds and hear reflected sound waves to pinpoint objects in their flight path. Griffin called the sensory-acoustic form of bats navigational echolocation.
Echolocation is the use of sound waves and echoes to determine where and how far objects are.
The ability to detect and emit ultrasonic frequencies above the human hearing range is an essential survival tool for more than just bats. Nocturnal and marine animals rely on sensitive systems to navigate and locate prey, while some insects use ultrasonic hearing to detect predators. This ability is important for many animals.
Ultrasonic principle
Ultrasonic sensor module consists of a transmitter and a receiver. Any sound above 20 kilohertz (20,000 hertz) is considered ultrasound. For this reason, all sounds above the human hearing range are called ultrasonic. The transmitter emits 40 kHz ultrasonic radiation, and the receiver is only designed to receive 40 kHz sound waves. A receiver sensor close to the transmitter can pick up reflected sound waves when the module hits any obstacle ahead.
Whenever there are obstacles in front of the ultrasonic module, it calculates the time it takes to send signals and their reception, since time and distance are associated with sound waves passing through the air at a speed of 343.2 m / sec. After receiving the signal, the data is shown on the display. Thus a wide range of materials can be measured, including:
- hard or soft;
- colored or transparent;
- flat or curved.
Device and technical characteristics
These instruments can determine the height, width and diameter of objects using one or more sensors. Items can be selected or rejected depending on their sizes or profiles.
An ultrasonic distance sensor detects the space to an object by measuring the time it takes for sound to reflect it. The frequency of the sound is in the range of ultrasound, which provides a more accurate direction of the sound wave. This is due to the fact that sound at a higher frequency is scattered in the environment.
The device contains two diaphragms. One of them produces sound, and the other receives the reflected echo. The diaphragms in the device are usually a speaker and a microphone. The sound generator generates short ultrasonic pulses and starts a timer. The second membrane registers the arrival of a sound pulse and stops the timer. From the time obtained, you can calculate the path that the sound has traveled. The distance to the object is half the distance traveled by the sound wave.
Application and benefits
Distance sensors are widely used in everyday life. Cars are equipped with parking sensors. In addition to measuring distances, they can simply register the presence of an object in the measuring range, for example, in hazardous areas of working machines. Such devices used in a wide range of industries, for example:
-
in the press; - when converting;
- in robotics;
- during the processing of materials;
- in transportation, etc.
Distance sensors can be used to monitor or indicate the position of objects and materials. These instruments are so widely used that they can be reliably implemented in measurement applications granularity of the material, determination of the water level and much more, since ultrasound is reflected from almost any surfaces. The only exceptions are soft materials such as wool. Its surface absorbs ultrasonic waves and does not reflect sound.
Ultrasonic distance meters are superior to infrared sensors because they are unaffected by smoke and other factors. While this system is not completely perfect, it is a good, reliable and economical solution for detecting distances and obstacles.
The gadgets connect to all common types of automation and telemetry tools. Applications range from simple analog connections to complex multi-sensor data networks.
