Design Of High Precision Level Gauging And Control System For Marine

With the development of ship automation, level gauging system is becoming an important part of ship supporting system. It is widely applied in new ship built in recent years. Level, cabin volume, temperature, pressure and other parameters can be measured by level gauging system and the system can also alarm for abnormal situation. Level and capacity value are important indicators of vessel monitoring parameters, the running posture of the ship can be changed by adjusting the cabin level value. In order to control the running posture accurately and ensure the safety of ship navigation, the requirement of liquid level measurement accuracy is becoming increasingly stringent. In this thesis, a precision level gauging and control system is designed. The design of hardware and software and the confirmatory test analysis are based on level measurement theory and system accurate measurement theory. The test results show that the system is accurate and stable with good practical values.The main works in this thesis are as follows:1. The thesis analyzes the principle of pressure measurement method and radar level measurement method. Then, based on the comparison of two level measurement methods, the thesis presents two frame diagrams of level gauging system.2. Analyzing several main factors that influence the measurement accuracy of the level gauging system and describing the precise measurement of cabin's level and tank capacity in detail. The precise measurement of level is mainly divided into three aspects including the correction of the measured value from the sensors, the correction of the inclined level caused by the roll and trim of the ship and the filtering process of the fluctuant level. Among them, the Extended Kalman filter and low pass filter are used to realize the filtering of the fluctuant level. In addition, the thesis proposed an accurate liquid level measurement method based on multi sensor fusion. The accurate measurement of the cabin capacity is mainly worked to obtain the accurate capacity curve by subsection fitting method.3. On the basis of the structure of level gauging and control system, the working principle of each subsystem and the selection of hardware equipment and the connection mode are explained in detail.4. According to different hardware connection, the setting of data acquisition module based on Utility DCON and the design of PC monitor and control program based on MODE TRACE 6 configuration software are completed. In addition, based on C#.NET platform, a set of query interface for measuring, controlling and alarm function of the system is developed.5. Two ways are used to test and verify the system. On the one hand, the accuracy of the system is verified by single tank. On the other hand, in order to further verify the feasibility and accuracy of the system, the designed system is applied to the floating dock model to carry out experimental verification.