In robotics and engineering in general, sensors play a major role in providing an accurate and precise measure for the different devices we are using in order for the devices to operate the way they do, in other words, sensors extend the capabilities of the devices that we use in our day to day lives such as cars, smartphones, airplanes, and many other devices.
Ultrasonic is a type of sensor that is used to measure distances, it is used in cars, trash level monitoring, liquid level sensing, used in production lines, and many more.
In this article we are going to dissect this sensor and analyze how it works, it’s major characteristics, how it’s used and integrated into projects, and how to get the most out of it if you’re going to use it in your own projects.
So let’s get started …
The Working Principle of Ultrasonic Sensors
The ultrasonic sensor consists of a transmitter and a receiver, the transmitter generates high-frequency sound waves that the human ear can’t hear, those waves hit the objects that are in the range of the sensor and gets reflected by those objects, then the receiver collects the reflected waves and based on the time interval between sending the wave and collecting it the distance of the object gets calculated.
Types Of Ultrasonic Sensor
There are three main types for ultrasonic sensors and they are:
- Diffuse Proximity Ultrasonic Sensor
- Retro-Reflective Ultrasonic Sensor
- Through-Beam Ultrasonic Sensor
Diffuse Proximity Sensor
The diffuse proximity sensor works as we described above in the working principle section, the sensor consists of two components: a transmitter, and a receiver and the transmitter generates bursts of high-frequency sound waves and if there’s an object it will echo these waves and the transmitter will receive the signal.
This sensor is ideal for detecting:
- Granules or Powders
Retro-Reflective Ultrasonic Sensor
This type of sensor is the same as the one above but it adds a reflector fixed in front of the sensor, the reflector reflects all the waves generated by the transmitter and it is fixed at a constant distance from the sensor, so if an object passes through the distance between the sensor and the reflector it would be detected.
This type of sensors is ideal for detecting sound absorbents and sound deflecting material.
Ultrasonic through-beam sensors
These type of sensors differ from the other two in that the transmitter and the receiver are separated into two different housings and they are placed or fixed in front of each other so the waves that get transmitted from the transmitter gets received by the receiver on the other end.
Ideal for applications that require the detection of a continuous object.
Advantages & Disadvantages Of Ultrasonic Sensors
Ultrasonic sensors have many advantages that make them a great option to choose when designing your system, these advantages are:
- They’re not affected by color or transparency of objects.
- Can be used in dark environments.
- Not highly affected by dust, dirt, or high moisture environments.
- Most of the ultrasonic sensors are a low-cost option.
The disadvantages of the ultrasonic sensors are:
- Cannot work in a vacuum, because sound waves need matter to carry it.
- Limited detection range.
- Sensing accuracy is affected by soft, curved, thin, and small material.
- Sensing accuracy is affected by changes in temperature.
Applications Of Ultrasonic Sensor
Ultrasonic sensors can be used for so many purposes, generally these purposes can be categorized into detection, measurement, and destruction.
Ultrasonic sensors can detect :
- Thickness of subcutaneous fat/muscles
- Foreign substances contained in food
- Internal of concrete/metals
And they can measure:
- Flow velocity/rate
- Eye axis length
And the can destroy:
- Cells, which is useful for destroying cancer cells.