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

• 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

• f 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 Background

• 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 microcontroller, 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

• f 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 Potential difference across the soil Soil acidity Soil moisture

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 microwave Add deionized water Mix thoroughly

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%,

40% and 50% moisture.

Figure 6. Set Up of Moisture / Acidity Experiment

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 raw soil Mix thoroughly Verified by pH meter

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 H2O(l) → O2(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

• utput.

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

Thank you!