Double Phase Digital Detection Method For Ultrasonic Large Size Measurement

With the rapid development of China’s economy and society, technological level of automation continuously improve.various types of industrial control, intelligent obstacle avoidance, intelligent robotics, industrial automation, and other fields of high-precision ranging proposed strict requirements.In this paper, the method of ranging is using ultrasonic wave.Ultrasonic ranging is suitable for a wide range, not sensitive to light and electromagnetic fields, and be suitable for the harsh environment.The ultrasonic sensor is simple in structure and is easy to achieve miniaturization and integration.Based on the traditional ultrasonic distance measurement, the paper aims to improve the measuring range and the measurement accuracy.A new method of the ultrasonic phase difference detection based on ultrasonic A/D sampling method is proposed in this paper.The method can eliminate the impact of DC component on the detection of phase difference by utilizing the difference of ultrasonic signal on adjacent sampling data, and then the mathematical model of the phase difference detection is set up by the ratio of the difference between the different adjacent sampling data, thus obtaining high resolution of phase difference detection.Sampling circuit of this method is simple with no need for high degree of ultrasonic signal sampling rate, but it only needs to sample a dozen of data in a period of ultrasonic signal, afterwards, the submicron level; of resolution of displacement measurement can be obtained.Experimental and simulation results can verify the effectiveness of this method.If the ultrasonic frequency on the platform of ultrasonic displacement measurement is 40kHz, the resolution of displacement measurement will reach to 1μm, which is developed by this method.In the aspect of large size measurement, a kind of double phase displacement measuring method is adopted.Use of signal modulation, the ultrasonic signal as the carrier signal, low frequency signal to modulate the ultrasonic signal.Using phase detection algorithm to measure the phase difference of the low frequency modulation wave after the modulation and demodulation, get the rough measurement of the displacement in the large size measurement.The ultrasonic phase difference is used to measure accurately, and the measured value of the modulated signal is modified to improve the accuracy of the displacement measurement in large size range.