Development Of Measurement And Control System For Ship Borne Precipitation Sensor

Precipitation data is the gauge to provide relevant water resources.It is an essential data for the national economic construction and scientific research departments of the country,especially for meteorology,hydrology,and agriculture.It is an important parameter in the fields of meteorology,hydrology,and flood prevention.Since most of the global precipitation falls on the ocean,it is very important to measure the precipitation on the ocean.Several commonly applied precipitation sensors(such as tipping bucket type,weighing type,etc.)have excellent overall performance,high resolution and reliable accuracy and many other advantages.They could be applied to measure precipitation accurately on land,but if they were placed on platforms such as ships that being always in motion,they could be affected by shaking,etc.,making the measurement result error larger.Therefore,a marine precipitation sensor based on capacitor has been developed in this thesis,according to the change of capacitance caused by the change of volume ratio of liquid and air in the sensor,the precipitation could be calculated by measuring the changed capacitance.Because the proportion of water and air in the sensor could not be changed by shaking,no matter how the shape of rain changes when the sensor shakes or swings,the constant proportion of water and air could measure the precipitation in real time and accurately.In this thesis,various types of capacitive sensors have been analyzed in detail.According to their respective characteristics and principles,the cylindrical capacitive sensors with variable medium has been selected.On this basis,the marine precipitation sensor has been designed.In the hardware part,the material and size of the capacitance sensitive element,has been determined,and then in order to meet the requirements of different meteorological instrument interfaces,a capacitance detection circuit containing two different output modes of analog signal and digital signal has been designed,and finally the minimum system of single-chip microcomputer has been designed.After the hardware design has been completed,the software design has been carried out to realize the control of the capacitance detection circuit,signal acquisition,data processing and transmission,etc.,and a fault self-diagnosis module has been designed in the single-chip microcomputer.Finally,the designed sensor has been tested and verified,the result shows that the resolution and accuracy of the two signal output modes of the designed marine precipitation sensor in this thesis meet the requirements of technical indicators,and are reliable and stable.At the same time,the fault diagnosis is fast and accurate,and the system automatically diagnoses could instead of manual detection and troubleshooting.The accuracy rate has reached 90%,which improves the diagnosis and maintenance efficiency of the marine precipitation sensor.