| This paper is a technology application and research which follows the requirements of hydrological automatic measuring and reporting system in Yellow River. It is financed jointly by two funding, one is Specialized Research Fund for the Doctoral Program of Higher Education of 2009 called "The Research for Application and Mechanism Method Used in Hydrological Information All-weather Environmental Automatic Monitoring Based on the Physical Property Difference of Air, Ice and Water"(Project Number: 20091402110004), and the other is Outstanding Graduate Innovation Project in Shanxi Province of 2009 called "The Research of Remote Telemetry System for Hydrological Information and Ice Jams Disaster Based on GSM/GPRS "(Project Number:80010402100171).Ocean, lake, river, reservoir freeze in winter is a normal physical phenomenon, but severe ice scourge will bring harm to the normal operation of engineering construct over water, aquaculture and water transportation. For the abnormal change of climate in recent years, the continued occurrence of river ice flood and sea-ice disaster seriously affected the national economic development and people's normal life, even posed a grave threat to people's lives and property. If ice slush and sea ice could be automatically detected, river ice flood and sea ice scourge will be warned, disaster losses will be reduced to a minimum. Ice-thickness is a key physical parameter which characterizes the change of ice condition. Based on the measuring principle of difference in capacitance among air, ice and water, the author improved the original ice-thickness sensor and designed a new capacitive ice-thickness detecting system using capacitance-to-digital converter PS021. This paper mainly includes the following sections:1. Based on a large quantity of technical literatures, this paper goes into details of micro-capacitance measuring circuits and the detections of ice thickness on the current situation both at home and abroad. At last the measuring principle of difference in capacitance among air, ice and water and capacitance-to-digital converter PS021 is chosen.2. Depending on the actual application in detection of Yellow River ice slush, a large number of field mechanism experiments has been done using original capacitive sensor and capacitance measuring instrument, the structure of parallel plate capacitive sensor has been optimized. The feasibility of measuring principle of difference in capacitance among air, ice and water has been further proved through theoretical calculations and modeling capacitance simulation.3. On the basis of theoretical analysis and experiment, a new ice thickness measurement system has been designed and the corresponding data processing software has been written. MSP430F169 is used as master control single-chip in the whole system. Chip Select Circuit gate each paralleled plate electrode from one to the other under the control of single-chip, PS021 sent capacitance value to single-chip through SPI bus, then calculation and storage of data is completed by single-chip. Data-processing software realizes the control of single-chip and function of each hardware module, which is compiled using C language.4. Theory, structure and the feasibility of single planar multi-electrode capacitance sensor using in ice thickness measurement are discussed in the paper.Experimental data of PS021-based ice thickness capacitive detection system is analysised, and compared with experimental data of the original detection system, conclusion is obtained that the interfaces of air and ice, ice and water are distinguished. Shortage of new type capacitive sensors and followed improving direction are pointed out simultaneously. |
