What is the working principle of ultrasonic transducers? How to help the car back up?

It can inform the driver about the obstacles around with a sound or a more intuitive display, which relieves the driver of the trouble caused by the front and rear and left and right visits when it is parking, reversing and starting the vehicle, and helps the driver to remove the blind spots and blurred vision defects, improve driving safety.

Ultrasound (referred to as a mechanical wave with a frequency above 20 kHz) is a special sound wave with basic physical characteristics such as sound wave refraction, reflection, and interference. The ultrasonic ranging transducer sends out ultrasonic waves through the ultrasonic transmitting device, and the time difference when the transmitted ultrasonic waves are received through the receiver to measure the distance length.

The ultrasonic transmitter emits an ultrasonic signal in a certain direction outside, and starts timing at the same time as the ultrasonic wave is transmitted. The ultrasonic wave is propagated through the air. When an obstacle is encountered during the propagation,ultrasonic transducer depth measurement will be reflected back and propagated back immediately. The time of the wave stops immediately. The propagation speed of ultrasonic waves in the air is 340m/s, and the timer can measure the distance (s) from the launch point to the obstacle by recording the time t, namely: s=340t/2.

Ultrasonic energy consumption is relatively slow, the propagation distance in the medium is relatively long, the penetration is strong, the method of distance measurement is simple, and the cost is low. However, it has certain limitations by measuring distance at high speeds. This is because the transmission speed of ultrasonic waves is easily affected by weather conditions. In different weather conditions, the transmission speed of ultrasonic waves is different and the propagation speed is slow. When the car is driving at high speed, the ultrasonic distance measurement cannot keep up with the real-time change of the car distance, and the error is large. On the other hand, the ultrasonic scattering angle is large and the directivity is poor. When it is measuring a long-distance target, its echo signal will be relatively weak, affecting the measurement accuracy. However, in short-distance measurement, the ultrasonic ranging sensor has a very big advantage.