An English literature on ultrasonic rangefinders is urgently needed

Hello! Mingyang ultrasound will answer for you:

The formula for ranging is expressed as: l=c t

where l is the length of the distance to be measured; c is the propagation speed of ultrasonic waves in the air; t is the time difference between the measured distance propagation (t is half of the value of the transmit to receive time).

Ultrasonic ranging is mainly used in the distance measurement of reversing reminders, construction sites, industrial sites, etc., although the current ranging range can reach 100 meters, but the accuracy of measurement can often only reach the order of centimeters.

Because ultrasonic waves are easy to be emitted directionally, have good directionality, easy to control intensity, and do not need direct contact with the object to be measured, it is an ideal means for liquid height measurement. In the precision level measurement, it is necessary to achieve millimeter-level measurement accuracy, but at present, the domestic ultrasonic ranging special integrated circuits are only centimeter-level measurement accuracy. By analyzing the causes of ultrasonic ranging errors, improving the measurement time difference to the microsecond level, and compensating the sound wave propagation speed with the LM92 temperature sensor, the high-precision ultrasonic rangefinder we designed can achieve millimeter-level measurement accuracy.

To increase the maximum measuring distance:

One is to increase the ultrasonic transmission power;

The second is to increase the magnification of the receiving circuit, both of which may increase the minimum measurement distance, but one of the biggest problems is that the minimum measurement distance will increase. In order to solve these contradictions, it is necessary to add an automatic gain control circuit to the ultrasonic receiving circuit to solve the above contradictions.

Increase the transmitting voltage and increase the amplification of the receiving circuit.

Is this design not enough IO port of the single-chip microcomputer, if there is no problem with the software, it must be a hardware problem.

Here the unit of time should be us, and the speed of sound is assumed to be 344 seconds s distance distance = time * 10 -6 2 * 344 The unit of distance here is meters, and the unit of distance is as follows when converted into cm.

time*10 -6 2*344*100=time*i.e., distance=time*; Centimeter.

Because ultrasonic waves have strong directionality, slow energy consumption, and long distances in the medium, ultrasonic waves are often used for distance measurement, such as rangefinders and level measuring instruments. The use of ultrasonic detection is often relatively fast, convenient, simple to calculate, easy to achieve real-time control, and can meet the requirements of industrial practicality in terms of measurement accuracy, so it has also been widely used in the development of mobile robots.

In order for the mobile robot to walk automatically to avoid obstacles, it is necessary to equip a ranging system so that it can obtain the distance information (distance and direction) from the obstacle in time. The three-direction (front, left, and right) ultrasonic ranging system introduced in this article is to provide a movement distance information for the robot to understand its front, left and right side environment.

The principle of ultrasonic good scattered wave ranging is to emit ultrasonic waves from the superstate dust acoustic wave transmitter, which is based on the time difference when the receiver receives the ultrasonic wave, which is similar to the principle of Zenda ranging of Lei Fan Socks.

Ultrasonic distance measurement sensor, using the principle of ultrasonic echo ranging, using accurate time difference measurement technology, detecting the distance between the sensor and the target, using small angle, small blind area ultrasonic sensor, with accurate measurement, no contact, waterproof, anti-corrosion, low cost and other advantages.