Ultrasonic sensors are sensory devices that convert electrical energy into ultrasonic waves. The principle of operation is similar to radar, as they detect a target based on the interpretation of the signal that is reflected from them. The speed of sound is a constant value, so using such a 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 area of their use. It is possible to single out a short range, directivity of the signal, low speed of wave propagation. The main advantage of ultrasonic sensors is their relatively low cost. In cars, they can be used to organize parking systems. Ultrasonicextended range level sensors are actively used in a number of designs of assistance systems for monitoring blind spots. They are also used in a variety of car control systems in automatic mode.
As the basis of the sensor can be called a converter that combines the active element and the diaphragm. In this case, the transducer functions as a transmitter and receiver. The active element generates a short pulse, which is then received as 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 transducer, allowing the acoustic characteristics to be determined. The base of the transducer is sufficiently resilient to absorb vibrations. All elements are in a plastic case equipped with connectors for connection.
Ultrasonic sensors work like this: when receiving a signal from the outside, the active element causes the diaphragm to vibrate, sending ultrasonic pulses into space. When these waves meet with 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, speed. Modern parking devices have a frequency of 40 kHz, and a detection range ofup to 2.5 meters.
Manufacturers usually do not indicate the value of such an important parameter as the viewing angle. In sensors, the angle of view is usually determined by the frequency of the signals and the shape and size of the transducer. The higher the pulse frequency, the smaller the viewing angle will be.
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 heavy pollution. The sensor is capable of passing small objects as well as low reflective surfaces.
