1、度；超声波；测距华北科技学院毕业设计（论文）III IntroductionAt present, ultrasonic ranging technology has been widely applied in various fields, because of its non-contact measurement, in industrial field level, well depth, pipeline length and the measurement of buildings, reversing radar, intelligent robot control syste
2、m play an important role. But in our current level of technology, the application of ultrasonic ranging technology is limited, the future direction of development should be towards high precision, low area, develop the function more abundant and lower cost price direction.And ordinary ultrasonic ran
3、ging system is different, high-precision ultrasonic ranging system requirements of the blind area is smaller, higher accuracy. In order to achieve the standard, the design system contains the temperature compensation circuit, the Dual Comparator plastic circuit and the time gain compensation circuit
4、 and other signal conditioning circuits. Finally, it is necessary to add some necessary peripheral circuits such as display circuit, used to display the measurement results must also contain communication interface, convenient and PC communication and can be used to upload the measurement results. I
5、n addition, the system of the peak detection software, make the circuit more simplified, fully utilize the software resources.Through the analysis of the system needs, the hardware circuit design scheme is finally determined, and the main control chip is the main chip of AT89C52.In order to achieve
6、the high accuracy, we need to understand the cause of the low accuracy of the measurement. Firstly, the transmission speed of the acoustic wave in the air will change with the temperature. The distance and the actual distance calculated by the average velocity may have some error.The second is becau
7、se the ultrasonic belongs to one kind of wave, so the diffraction characteristic of wave is of the wave. This will make the ultrasonic wave not reflected, that is not due to the wave of the object returned, but directly received the emitter due to diffraction phenomenon and changed the direction of
8、the transmission of that part of the ultrasonic. This is the result of a blind measurement of the blind, in the measurement of the error caused by the error read while the measurement failed. Therefore, as long as adding temperature 基于单片机的高精度超声波测距系统的设计IV compensation circuit, by a temperature sensor
9、 to measure temperature, the actual temperature into the calculation, can effectively avoid the error of the first kind; Secondly, adding dual comparator circuit, can effectively avoid the second type of error. The system is controlled by the AT89C52 microcontroller count as well as the transmitter
10、and receiver of ultrasonic wave. The whole circuit uses the idea of modular design, including the display circuit, ultrasonic circuit, ultrasonic receiving circuit, temperature compensation circuit, etc. The display circuit is mainly composed of LED digital tube, and the dynamic display is adopted.
11、That is, all the digital control of the section of the line in parallel, through the control of the selected signal to control the light of the digital tube. Secondly, transmit circuit for ultrasonic signal which is transmitted by the main gate, and the ultrasonic probe. There are also used for ultr
12、asonic receiving circuit, the echo filtering amplification, shaping, and finally into the microcontroller. Other circuit also includes a temperature measurement circuit for measuring the temperature of the environment, mainly by a chip directly read environmental temperature, into the microcontroller, then through query well in advance of the thermometer, current measurement environment in the actual sound velocity through this t
