Ultrasonic Level Sensor Design And Ranging Algorithm

In the field of industrial measurement, position measurement by ultrasonic is a frequently used non-contact measurement method. The present study did further researches centering on the hardware and software design of ultrasonic position sensor and discussed three algorithms to process ultrasonic signals. The static parameters of the designed transducer were calibrated.On the basis of investigation on current situation of ultrasonic position sensors in domestic and abroad, the related technical specifications of the ultrasonic mechanical characters, the function of transformation, and the ultrasonic transducer are introduced. By contrasting the common principles of position measurement by ultrasonic, the paper identify the ranging method for the overall design. In the aspect of hardware circuit design, according to different ASIC, the paper puts forward two kind of ultrasonic emitting and receiving circuits. The hardware part focuses on the pulse transformer driver circuit and its function of matching to the transducer, while briefly introduces the design procedures and circuit structures of the microprocessor, the temperature detection circuit and the LCD display circuit. In the aspect of software design, the paper introduces the management method of microprocessor ports and the program design of PCA capturing module, and emphasizes the overall workflow. According to the features of the ultrasonic echoes, the cross-correlation method, the method based on NLMS arithmetic and the wavelet analysis method are used to process and analyze the ultrasonic signals. At last, two different kind of ultrasonic position sensors are calibrated and their static parameters are obtained respectively.The experimental results present that the two kinds of the ultrasonic position transducers have many practical advantages, such as high precision, good linearity, good repetition and small hysteresis. Simulation tests show that the ability to avoid noises of the cross-correlation method makes itself more suitable for solving the stability problems of long distance measurement.