NANYANG RESEARCH PROGRAMME NRPjr05B Remote Earth Monitoring Station - PowerPoint PPT Presentation

NANYANG RESEARCH PROGRAMME NRPjr05B Remote Earth Monitoring Station Bai Yuanyuan Lu Xiling Raffles Girls’ School (Secondary) Associate Professor Paul Lee Choon Keat National Institute of Education Shaun De Souza Raffles Girls’ School (Secondary)

Presentation Outline Introduction and Aim ● Literature Review ● Methodology ● Results and Analysis ●

1. Introduction and Aim

1. Introduction and Aim Soil moisture and acidity ➔ Agricultural and environmental conditions ➔ Plant health ➔ Global food supply

Background 1. Introduction and Aim Under this global context, the project aims to construct a system that monitors the moisture and acidity of the soil economically -- the remote earth monitoring station. Utilizing electrolysis on soil sample as the main experimental mechanism, the station determines the chemical properties of the soil by measuring more easily accessible physical data such as current and potential difference across the soil samples. The main objectives: accuracy of data monitored sensitively ● Data obtained is compared with theoretical prediction. ○ low cost ● Monitoring system programed on board esp32 via arduino platform ○

2. Literature Review

2. Literature review ● Remote Sensing and Control of an Irrigation System Using a Distributed Wireless Sensor Network by Professor Yunseop Kim, Robert G. Evans, and researcher William M. Iversen. The paper provides a feasible and available method to build a remote measurement system and outlines its basic rationale. ● PMMA-Coated Capacitive Type Soil Moisture Sensor: Design, Fabrication, and Testing , by Moupali Chakraborty, Anindita Kalita, Karabi Biswas from the Department of Electrical Engineering, IIT Kharagpur, Kharagpur, India ● Use of Glass Electrode to Measure Acidities in Deuterium Oxide by Paul K. Glasoe and F. A. Long

3. Methodology

Ⅰ . To perform electrolysis, an embedded circuit is built on a m icrocontroller, transmitting the collected data from the station to the user terminals. Ⅱ . To identify the different conditions of soils, electrolysis is performed on the targeted soils to distinguish their different current and voltage patterns under the given electromotive force.

3.1 PROGRAMMING OF THE MICROCONTROLLER ● The simplified diagram of the embedded system on microcontroller (board esp32) Figure 1. Embedded circuit on the microcontroller

Two DAC Ports: During electrolysis, an alternating voltage is produced by two DAC ports to ensure that the electrodes do not undergone continuous oxidation or reduction so that they would be worn out easily. Figure 2. Graph showing the output voltage/v Figure 3. Graph showing the output electromotive of DAC 1 and DAC2 against time/ms force/v against time/ms

Hall-effect Sensor: Monitoring the current through the circuit by detecting the magnetic field of a resistor. ● With reference to equation , the magnetic field strength at a fixed distance away is ● proportional to the current through the conductor. A solenoid of wire is built outside the hall-effect sensor to amplify magnetic field strength. ● Amplifier: Amplifier MCP6002 ● Amplify the alternating voltage ● Located on two DAC ports respectively ●

Handleclient: As an important part of ● the programme, “handleclient” is run after each collection of data To update data to the ● users in regular intervals Fig. 5 Flowchart of the Program Structure

3.2 ELECTROLYSIS OF SOIL SAMPLES Based on literature review, under given electromotive forces, soils of different conditions ● give different current values and output voltages ( the potential difference between the two electrodes Current through the soil Soil acidity Potential difference across the Soil moisture soil

3.2.1 MOISTURE EXPERIMENT Aim of experiment : To find the current and potential difference across the soil sample of different moisture . ● Targeted soil sample: Soil samples of 10%, 20%, 30%, 40% and 50% moisture ● Preparation of soil sample: Dry the raw soil mildly using Add deionized water Mix thoroughly microwave

3.2.1 MOISTURE EXPERIMENT Under the given electromotive forces that has been ● programmed, the current and potential difference between soil of 10 % moisture are obtained accordingly. Due to the alternating current and voltage, the ○ average of their amplitudes in 10 periods is calculated. Repeat the process two more times and calculate the ● average. Repeat the experiment with soil samples of 20%, 30%, ● Figure 6. Set Up of Moisture / Acidity Experiment 40% and 50% moisture.

3.2.1 ACIDITY EXPERIMENT Aim of experiment : To find the current and potential difference across the soil sample of different acidity . ● Targeted soil sample: Soil samples of pH values 3, 5, 7, 9, 11 ● Preparation of soil sample: Add diluted sulfate acid/ calcium hydroxide in the Mix thoroughly Verified by pH meter raw soil

3.2.1 ACIDITY EXPERIMENT Under the given electromotive forces that has been ● programmed, the current and potential difference between soil of pH 3 are obtained accordingly. Due to the alternating current and voltage, the ○ average of their amplitudes in 10 periods is calculated. Repeat the process two more times and calculate the ● average. Repeat the experiment with soil samples of pH = 5, 7, 9, 11. ● Figure 6. Set Up of Moisture / Acidity Experiment

4. Results and Analysis

4.1 Calibration Result of hall effect sensor Readings from hall effect sensor are originally numbers ranging from 0-4096 with arbitrary units 0-2048 → direction of detected magnetic field is ● in reversed direction 2048-4096 → direction of detected magnetic ● field is in the positive direction Calibration result: Approximately a straight-line graph → consistent ● with theoretical prediction Current -2mA-2mA → reading 0-4096 ●

4.2 Result of Soil Moisture Experiment A clear upward trend in the ● amplitude of current against soil moisture 2 H 2 O(l) → O 2 (g) + 4 H + (aq) + 4e - ● More water → more free electrons ● giving out → greater current

4.2 Result of Soil Moisture Experiment a clear downward trend in the ● amplitude of output current against soil moisture Higher moisture content → ● greater current → lower resistance → lower voltage distribution

4.2 Result of Soil Moisture Experiment

4.3 Result of Soil Acidity Experiment When the soil is neutral, there is a ● maximum amplitude of voltage output.

4.3 Result of Soil Acidity Experiment When the soil is neutral (pH=7), ● there is a minimum amplitude of current

4.3 Result of Soil Acidity Experiment

5. Conclusion

5. Conclusion In conclusion, the constructed remote earth monitoring station exhibits a high sensitiveness to the changing soil moisture and acidity. The obtained data are also accurate as seen from their coherence with the group’s hypothesis and preliminary research. The station achieves its task economically, built on a microcontroller of as cheap as 10 SGD.

Assumptions and Limitations Assumptions: 1. The acid that contributes to the soil acidity is largely ionic acid instead of organic acid 2. Except for the investigated variables, the effect of other chemicals in the soil is negligible. Limitations: 1. The research only focuses on one type of soil 2. In the research, when investigating certain variable the other conditions are controlled. While in real life, the factors may change concurrently.

Reference [1] Chakraborty, M., Kalita, A., & Biswas, K. (2019). PMMA-Coated Capacitive Type Soil Moisture Sensor: Design, Fabrication, and Testing. IEEE Transactions on Instrumentation and Measurement,68(1), 189-196. doi:10.1109/tim.2018.2838758 [2] Glasoe, P. K., & Long, F. A. (1960). Use Of Glass Electrodes To Measure Acidities In Deuterium Oxide 1,2. The Journal of Physical Chemistry,64(1), 188-190. doi:10.1021/j100830a521 [3] Kim, Y., Evans, R., & Iversen, W. (2008). Remote Sensing and Control of an Irrigation System Using a Distributed Wireless Sensor Network. IEEE Transactions on Instrumentation and Measurement,57(7), 1379-1387. doi:10.1109/tim.2008.917198 [4] MCP6001/1R/1U/2/4[PDF]. (n.d.). 2009 Microchip Technology Inc. [5] ESP32 Pinout Reference: Which GPIO pins should you use? (n.d.). Retrieved Nov 6, 2018, from https://randomnerdtutorials.com/esp32-pinout-reference-gpios/ [6] DRV5055 Ratiometric Linear Hall Effect Sensor[PDF]. (2018). Texas: Texas Instruments Incorporated

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