Design Of Liquid Level Detection System Based On Multi-sensor Information Fusion

With the increasingly serious energy crisis and environmental pollution, proportion of green energy in the industrial production is rising. As clean, safe, high efficiency energy, Liquefied Natural Gas(LNG) has become the protagonist of petrochemical resources. During the LNG transportation, it is an important safe guarantee to real-time monitor the position of tankers and the condition of LNG.The liquid level of LNG tankers is detected by means of the many distributed ultrasonic sensors in this paper. Signal conditioning and preprocessing are done by microcontroller circuit in a multi-sensor mode. Finally we explored the distributed multi-sensor data fusion technology based on Kalman filter.The hardware and software platforms of LNG level monitoring are built as a laboratory simulation mode in this paper. First, ultrasonic sensors is used to measure the liquid depth of the tank, weak analog voltage signal is feed in signal conditioning circuit under the control of MCU. Secondly, data acquisition, display, alarm and related mode settings are done in MCU, followed by the host computer. Finally, with the analyzed data, data curve are display by means of application software. In addition, information fusion algorithm for processing data is study to get a more accurate level.In addition, from the view of classical Kalman filtering theory, the LNG tank system can be regarded as time-delayed multi-sensor model. Aimed at the measurement data loss and transmission delay, a weighted matrix and state augmentation method are applied to modify the update equation. The distributed weighted matrix fusion estimation algorithm is designed. The cross-covariance matrix of filtering errors between any two sensors is given.The experiment results are shown that the measurement results can coincide actual data well. Furthermore, by means of the proposed system, the change of liquid level in LNG tankers can be monitored with the high accuracy and small volatility It has comparatively higher theoretical and practical value.