transmitting circuit of ultrasonic sensor

At present, foreign big car companies have invested a lot of resources to develop advanced anti-collision and safety warning systems for advanced cars with GPS, but the excessive cost limits its application in ordinary cars. To this end, greatly reducing the cost of the car's active anti-collision and safety early warning system, especially the cost of the ultrasonic distance sensor, will certainly promote the development and application of the popular car anti-collision warning system. In view of the fact that the development and testing of the domestic miniaturized millimeter-wave ranging radar is still in its infancy, the conditions for developing a domestically-made vehicle active collision avoidance system based on millimeter-wave radar are not yet mature. The main task of this project is to develop large-range ultrasonic sensors and large-range ultrasonic ranging systems for detecting surrounding objects within 20m or more from vehicles to replace expensive short-range radars; The robot automatic navigation and control system and the unmanned combat platform (ministerial “10th Five-Year” pre-research project) and other research projects provide technical support for target detection and positioning.

The structure of the ultrasonic distance range transducer, the electromechanical energy conversion efficiency of the ultrasonic transmitting circuit, the signal-to-noise ratio of the ultrasonic receiver, and the ultrasonic signal processing algorithm all affect the performance of the ultrasonic sensor and the ultrasonic ranging system. Therefore, in order to be able to develop ultrasonic ranging sensors and ultrasonic ranging systems with a frequency bandwidth of 20 to 30 m, good directivity and high response speed, measures must be taken from the following four aspects: First, optimize the ultrasonic proximity sensors mechanical structure, transmitting circuit and electromechanical impedance matching parameters to improve the electromechanical energy conversion efficiency of the ultrasonic sensor; second, select the appropriate form of the piezoelectric vibrator so that its resonant frequency is as low as possible in the frequency band to reduce the ultrasonic wave Energy attenuation during propagation; Third, increase the radiation area of the ultrasonic transducer as much as possible, adopt appropriate acoustic impedance matching technology and special transducer structure to enhance the directivity of the ultrasonic transducer and expand the ultrasonic sensor The working frequency band: Fourth, the design of low-noise, high-impedance ultrasonic receiving circuit, and the use of advanced digital signal processing methods to improve the processing gain and real-time performance of the ultrasonic distance measuring transducer.