Ultrasonic sensors are sensor devices that convert electrical energy into ultrasound waves. The principle of operation is similar to a radar, since they detect a target based on the interpretation of a signal that is reflected from them. The speed of sound is a constant value, so using this sensor you can easily set the distance to the object corresponding to the time interval between sending the signal itself and returning the echo from it.
Ultrasonic sensors have a number of features that allow you to determine the scope of their use. We can distinguish a small range, directionality of the signal, low velocity of wave propagation. The main advantage of ultrasonic sensors is their relatively low cost. In cars, they can be used to organize parking systems. Long
- range ultrasonic
level sensors are actively used in a number of assistance system designs for monitoring
blind spots. They find application in a variety of vehicle control systems in automatic mode.
As the basis of the sensor can be called a converter, which combines the active element and the diaphragm. In this case, the converter functions as a transmitter and a receiver. The active element generates a short pulse, which is then taken in the form of an echo from the obstacle. It is made from a special piezoelectric material. In this case, the aluminum diaphragm acts as the contact surface of the sensor, allowing you to determine the acoustic characteristics. The base of the transducer is elastic enough to absorb vibrations. All elements are in a plastic case, equipped with connectors for connection.
Ultrasonic sensors work like this: when a signal is received from outside, the active element leads to vibration of the diaphragm, which sends ultrasonic pulses into space. When these waves meet an obstacle, they are reflected, returning to the transducer, and create vibrations of the active element, from which the electrical signal is then removed.
Ultrasonic sensors have such basic characteristics as pulse frequency, obstacle detection range, and speed. For modern parking devices, the frequency is 40 kHz, and the detection range is up to 2.5 meters.
Manufacturers usually do not indicate the value of such an important parameter as the viewing angle. In sensors, the viewing angle is usually determined by the frequency of the signals, as well as the shape and size of the transducer. The higher the pulse frequency indicator, the smaller the viewing angle.
Ultrasonic distance sensors have a lot of undeniable advantages, but they also have very significant functional limitations. The performance and accuracy of the devices is reduced in bad weather conditions, as well as in severe pollution. The sensor is able to pass small objects, as well as surfaces with low reflectivity.