| The vortex flowmeter is widely used in the area of petroleum and chemical industry, because it has many advantages, such as no mechanical moving parts, easy installation, large turn-down ratio, and capability of being applied for the liquid and gas, etc. However, most of the vortex flowmeters currently used is stress-type, so the strong vibration of the pipeline always affects the measurement accuracy of the vortex flowmeters, especially when the power of the vibration is greater than that of the vortex flowmeters, in which condition the method of power spectrum analysis cannot get the correct results. Therefore, it is significant to find the method to obtain the accurate vortex flow frequency under strong disturbance. This paper studies the algorithm and the software of anti-strong vibration interference based on the single vortex flowmeter sensor.Improvements are made to the software of the system, aiming at the problems arisen from the practical application of the vortex flowmeter of anti-strong disturbance, which combines the digital filter based on the microcontroller and the autocorrelation algorithm to calculate the vortex flow frequency. The autocorrelation function is calculated by using real number FFT algorithm with assemble language based on MSP430F5418MCU in order to speed up computation. The calculation of the attenuation coefficient of the autocorrelation function is improved to ensure the measurement accuracy.The algorithm of cross correlating the noise template sequence with the signal power spectral sequence is proposed based on the noise template and the power spectrum estimation. The noise and vortex signal are distinguished according to the cross-correlation curve based on the normalization of the cross-correlation function of noise signal and the vortex signal. The sensor data collected in the vibration experiments are calculated by using this algorithm for verifying the effectiveness and applicability of the algorithm.Pneumatic regulating valve is widely used in chemical, metallurgical, electrical and pharmaceutical industries. As a core device of pneumatic regulating valve, the valve positioner plays a decisive role in control of pneumatic regulating valve. Among them, the intelligent piezoelectric valve positioner is used by many domestic manufacturers, because it has many advantages, such as flexible control, full-featured, etc. However, there are some problems of conventional five-step switch method of controlling the valve, such as over shoot, oscillation and unsmooth speed. So, it is significant to study the control method of the piezoelectric valve positioner.A five-step switching method with the backward PWM is proposed, which reduces the actuator speed effectively, minimizes the overshoot in the control process and eliminates the oscillation. A new method of parameter self-tuning is presented to obtain PWM duty cycle of different locations of the actuator. And the regulation time is reduced and the control precision is improved in the main control process.The real-time parameter self-tuning process and control algorithm are realized based on the hardware with a low power MCU MSP430F5418A chip. Experiments are performed with various pneumatic regulation valves, the result of which shows that the pulse numbers and the setting time is reduced greatly comparing with the five-step switching method, and the overshoot and oscillation are completely eliminated. |
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