| Summary: | 碩士 === 國立臺灣海洋大學 === 電機工程學系 === 97 === The development of inland fish cultivation in Taiwan has caught people’s eye gradually, and cage aquaculture will be for sure a future trend. However, the aquaculture has high labor cost and high risk, automatic monitoring system is thus needed. Therefore, cage automatic sensing system is the core technology. In this article, temperature, pressure and flow meter is installed at the cage, and a system is prepared; that is, an automatic environmental monitoring system for cage aquaculture is developed.
In this article, sensor readout circuit, 8051 control circuit are integrated so as to prepare an underwater environmental automatic sensing system. The output voltage of the readout circuit of the sensor is designed at the range from 0 to 5 volts, and the output voltage of the temperature sensor has a minimum designed at 0 volt, with temperature of -3.15℃±1℃; the maximum value is going to be designed by the control range of the control circuit, which is 5 volts, that is, 50℃±2℃.
In this study, after measurement and calculation on the output voltage of the designed temperature sensor circuit, we can obtain the average output voltage at room temperature to be 2.06 volts; for the A/D conversion of ACD0804, a reference voltage is given first to ACD0804, then ACD0804 will follow this voltage level to divide the voltage value into 255 equal divisions, then each division has sequential and different 8 bit digital signal to be sent back to ICL232 to perform series transmission, then the 8 bit digital signal is converted ASCII code that can be accepted by the receiving end of the computer. The temperature sensor of this study at 50℃ has average output voltage of 4.86 volts, hence, the reference voltage of ACD0804 is set up as5.1 volts, and the reference voltage level of the differential amplifier in the readout circuit is 2.70 volts, we can then obtain a temperature sensing range of -3.15℃±1℃~50℃±2℃.
The output current of pressure sensor is 4mA~20mA, which is linear output; for the load part, a 100Ω resistor is given, then a differential amplifier is used to take the voltage drop on the resistor, hence, the voltage drop on the load is from 0.4 volt to 2 volt, and the measurement depth range is water depth of 0~10 meters.
Finally, LabView is used to perform functional conversion on the sent-back ASCII code into temperature and water depth so as to form a cage automatic environment detection system.
Flow meter is package equipment. With the use of package software and its equipment, the parameters can be sent back to the computers.
In this article, series of experiments are conducted to confirm the usability of the system, which include water tank underwater experiment and yacht dock underwater experiment.
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