ULTRASONIC SENSORS

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Ultrasonic sensors can be used in detecting sound and as well as measuring liquid levels by using time of flight principles. As liquid level detector the ultrasonic transducer emits an ultrasound pulse usually in tens of kilohertz frequency ranges and then listens for the reflected pulse off from the liquid surface.

HC-SR04 Ultrasonic Sensors

HC-SR04 Ultrasonic (US) sensor is a 4-pin module device that uses sonar to determine distance to an object. HC-SR04 is an ultrasonic ranging module that provides 2 cm to 400 cm non-contact measurement function. The ranging accuracy can reach to 3mm and effectual angle is < 15°. It can be powered from a 5V power supply. It offers excellent non-contact range detection with high accuracy and stable readings in an easy-to-use package. Its operation is not affected by sunlight or black material like sharp rangefinders are (although acoustically soft materials like cloth can be difficult to detect). It comes complete with ultrasonic transmitter and receiver module.

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HC-SR04 Sensor Features

a. Operating voltage: +5V DC
b. Theoretical Measuring Distance: 2cm to 450cm
c. Practical Measuring Distance: 2cm to 80cm
d. Accuracy: 3mm
e. Measuring angle covered: <15°
f. Operating Current: <15mA
g. Operating Frequency: 40Hz
h. Max Range: 4m
i. Min Range: 2cm
j. Trigger Input Signal: 10µS TTL pulse

Mode of Operation

The ultrasonic sensor uses sonar to determine the distance to an object. Here’s how it does it:

The transmitter (trig pin) sends a signal: a high-frequency sound
When the signal finds an object, it is reflected and
The transmitter (echo pin) receives it.

Ultrasonic sensors make use of sound waves. These waves will echo off the target and return to the transmitter. Since the speed of sound is known, the time between the sound burst and return is translated into distance. It will also account for temperature when making calculations.

Use and Applications of Ultrasonic Sensors

Ultrasonic sensors have many uses and they can be applied in different projects and sectors. This list has been able to demonstrate that the use of sensors is highly important in any industrial process. The most astonishing information about these sensors is that they are cost efficient and have high adaptability. Therefore, making the ultrasonic sensors an affordable method of reducing waste in any production process.

These sensors are used for many purposes as mentioned earlier. We will be examining a few of these uses below.

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In beam detection for high-speed counting

Detection of things such as bottles is too fast to do with any other method than sensors. This makes ultrasonic through beam sensors great for this job. Ordinary ultrasonic sensors would just not work. The time between one bottle and the next is too short to allow the signal to bounce back for counting.

Robotic sensing

This is a field of study that is intended to give robots more human-like capabilities and attributes. Equipping the robot with a float level sensor will make the robot able to estimate the conditions in its immediate environment. With sensitive sensors, it can make out for objects in darkness.

Liquid level control

This function involves the ultrasonic water level sensor to be used as a control factor to control the flow rate in an industrial process. The sensors transmit signals which it uses in detecting the level of the liquid. This data from the liquid level sensor can then be used to control how much liquid is let into the inflow valve.

Loop control

Loop control enables high level of automation to be implemented. The great advantages are seen in a large technology system that can be operated by only a small amount of human resources. A good example of this is an ultrasonic water level sensor that is used in a nuclear power factory to ensure there is always enough water to be turned into steam.

Full detection

This is one of the most basic functions of an ultrasonic sensor. The liquid level sensor is attached to an industrial container to detect when it is full. If container is full, signals are sent to the controller, which shuts down the inflow valve. This helps to eliminate the chances of human error.

Thread or wire break detection

This is yet another important purpose when working with industrial equipment. It helps to ensure that all parts are working, as they should and that unavoidable breaks do not cause a break down in the production process.

Stacking height control

This is an important feature, especially when working on a production line. The robotic arms would not have any way of telling how much they have stacked unless they have a sensor. It helps to avoid catastrophic damages over stacking.

Inkwell level detection

During production, we may come across areas where detecting levels of liquids is important. However, the architecture of the factory’s building may make it impossible to reach these areas. In such a case, a random fair priced ultrasonic sensor will fulfill this role perfectly.

Detecting intruders

There are many instances when detecting people is important. For instance, a building may have a minimal number of occupants who are allowed at any time. It may also be for security purposes where a certain area is sensitive, and the presence of people is unwanted without warning.

Vehicle detection for car wash and automotive assembly

It is possible to inculcate automatic operating system into the operation of most car washing stations with usually one or no staff member. For such a car wash station to operate it must make use of the ultrasonic sensors. These sensors are also used in assembly plants to detect when new part is placed on the production line.

Irregular parts detection for hoppers and feeder bowls

Feeder bowls are used to feed industrial parts into a production line. If a part is defective, the only way to detect such parts is by use of sensors. The ultrasonic sensors use sound waves to detect parts that are not oriented in the right direction or that may be defective.

Profiling using ultrasonic system

Profiling is quite important in any production process. It helps to ensure evenness during production. One way of ensuring evenness in production lines is by the use of ultrasonic sensors. The good thing about these sensors is that dusts that may result from the production procedure does not affect the operation of these sensors.

Box sorting

Box can be sorted by use of multiple transducer monitoring system. Different shapes and sizes of boxes can be sorted into specific piles by use of this system. This increases work efficiency in the production.

Presence detection

Presence detection is quite easy to achieve. It can also be an important function of any production process. By using ultrasonic sensors, the production line can be halted or started depending on the presence or absence of parts.

Limitations of Ultrasonic sensors

Although the Ultrasonic sensor can be recommended for a bulk of technical applications it is not suited for every scientific application. Included below are limitations of the ultrasonic sensors, and how these problems can be overcome.

Cannot work in a vacuum

Because ultrasonic sensors operate using sound, they are completely non-functional in vacuums as there is no air for the sound to travel through.

Sensing accuracy affected by soft materials

Objects covered in a very soft fabric absorbs sound waves therefore making it hard for the sensor to see its target.

Have a limited detection range

Advanced Tank Level Measurements

Foams may obscure the air-to-liquid interface the ultrasonic sensors detects. Therefore, requiring more advanced sensor with advanced sensing capabilities. Two basic approach to resolving the limitation mentioned above.

Use of stilling tubes

A stilling tube is a simple vented pipe that extends from the top of the tank to just-short of the bottom. The sensor is placed at the top and the liquid level inside the tube follows the liquid level of the tank. The stilling tube protects the interior liquid from disturbances and provides a clear unobstructed path for the ultrasonic sound waves to follow. And since the liquid flows into the tube from the bottom where the liquid column exerts pressure, foaming is suppressed.

Use a built-in sensor logic to process or filter measurements.

For more information on the advantages and limitations of Ultrasonic sensors, click here